Re: [neonixie-l] Scope Clock SC200C

[Bill Notfaded]

Excuse the spell check phone post you get the idea lol!

Bill

On Monday, December 27, 2021 at 9:29:14 AM UTC-7 Bill Notfaded wrote:

> Terry-
>
> Seeing your comment about PCB's made me remember a story about GE Electric 
> in Schenectady NY.  A mentor of mine in WAN engineering worked there years 
> ago.  He said they had huge pools filled with PCB's and techs would wade 
> out into the pool in waders to tend to the pools.  He said one day someone 
> from GE environmental came around the office, where they had large 
> transformers mounted on walls above desks that sometimes leaked and 
> dripped.  He said the pamper said their may be some side effects who 
> exposure.  One side effect was it chipped turn your hair white.  My buddies 
> hair was pure white... not silver.
>
> Bill
>
> On Saturday, October 30, 2021 at 5:22:49 PM UTC-7 Terry Bowman wrote:
>
>> On Oct 30, 2021, at 6:17 PM, Tom Harris  wrote:
>>
>> Which is why you use a string of them in series for this sort of thing. 
>>
>>
>> My old HV scope probe has a resistor in it that's several inches long. 
>> It's rated something like 40kV and several rings in front of the handle to 
>> prevent arc-over. Must be for checking the high tension in a TV set. I also 
>> have a small laser power supply that I bought as a kit at a hamfest around 
>> '93. The bleeder on it is almost as long. 
>>
>> Like all laser PS kits I've seen the design is rather dodgy. The power 
>> transistor is only a TO-220 and the kit included a flimsy snap-on heat sink 
>> that gets too hot to touch in about fifteen seconds. I asked the seller 
>> about it and he said not to worry as the transistor was running within its 
>> heat spec. Right. When I can smell a transistor from across the room it's 
>> probably too hot.
>>
>> I retrofitted it with the most enormous vertical TO-220 heat sink I could 
>> find and even that got too hot to touch after a few minutes. Switching out 
>> the 0.5mW tube that came with the kit with a 0.25mW finally solved the 
>> problem.
>>
>>
>> With appropriate insulation, I saw glass tube used in a physics lab.
>>
>>
>> You can always fill the tube with transformer oil. Preferably the kind 
>> that doesn't have PCBs in it.
>>
>>
>> Terry Bowman, KA4HJH
>> "The Mac Doctor"
>>
>> Q: Should car stereo speakers be pointed to the rear for more thrust or 
>> up for more traction?
>>
>> A. On long trips, the 20- to 30% improvement in gas mileage you might get 
>> with speakers pointing to the rear is certainly worthwhile. On the other 
>> hand, if you drive on snow or ice, the extra traction of speakers pointing 
>> upward gives you added control.
>>
>> Don Lancaster
>>
>>

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Re: [neonixie-l] Scope Clock SC200C

[Bill Notfaded]

Terry-

Seeing your comment about PCB's made me remember a story about GE Electric 
in Schenectady NY.  A mentor of mine in WAN engineering worked there years 
ago.  He said they had huge pools filled with PCB's and techs would wade 
out into the pool in waders to tend to the pools.  He said one day someone 
from GE environmental came around the office, where they had large 
transformers mounted on walls above desks that sometimes leaked and 
dripped.  He said the pamper said their may be some side effects who 
exposure.  One side effect was it chipped turn your hair white.  My buddies 
hair was pure white... not silver.

Bill

On Saturday, October 30, 2021 at 5:22:49 PM UTC-7 Terry Bowman wrote:

> On Oct 30, 2021, at 6:17 PM, Tom Harris  wrote:
>
> Which is why you use a string of them in series for this sort of thing. 
>
>
> My old HV scope probe has a resistor in it that's several inches long. 
> It's rated something like 40kV and several rings in front of the handle to 
> prevent arc-over. Must be for checking the high tension in a TV set. I also 
> have a small laser power supply that I bought as a kit at a hamfest around 
> '93. The bleeder on it is almost as long. 
>
> Like all laser PS kits I've seen the design is rather dodgy. The power 
> transistor is only a TO-220 and the kit included a flimsy snap-on heat sink 
> that gets too hot to touch in about fifteen seconds. I asked the seller 
> about it and he said not to worry as the transistor was running within its 
> heat spec. Right. When I can smell a transistor from across the room it's 
> probably too hot.
>
> I retrofitted it with the most enormous vertical TO-220 heat sink I could 
> find and even that got too hot to touch after a few minutes. Switching out 
> the 0.5mW tube that came with the kit with a 0.25mW finally solved the 
> problem.
>
>
> With appropriate insulation, I saw glass tube used in a physics lab.
>
>
> You can always fill the tube with transformer oil. Preferably the kind 
> that doesn't have PCBs in it.
>
>
> Terry Bowman, KA4HJH
> "The Mac Doctor"
>
> Q: Should car stereo speakers be pointed to the rear for more thrust or up 
> for more traction?
>
> A. On long trips, the 20- to 30% improvement in gas mileage you might get 
> with speakers pointing to the rear is certainly worthwhile. On the other 
> hand, if you drive on snow or ice, the extra traction of speakers pointing 
> upward gives you added control.
>
> Don Lancaster
>
>

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Re: [neonixie-l] Scope Clock SC200C

[Toby Thain]

On 2021-10-30 12:28 p.m., GEK wrote:
Success!!! I really appreciate all of the help from Tristan and others.  
Nice to have my clock back.


Turns out the trace from blanking from pin 9 of the 74HC74 takes a very 
long route around the edge of the board in reaching pin 2 of U17 
(6N137).  There was a small defect in the copper trace that must have 
failed over time.  I was checking the blanking signal at the 74HC74 and 
missed checking the final connection to the 6N137.


The point about resistor voltage ratings is a good one, I often work 
with tube gear where this is an issue.


Great achievement, everyone loves a happy ending. Are you going to post 
a nice success screen pic?


--T



The CRT is a 3RP1A btw.  They've become pricey but fortunately seem to 
have a long lifespan.

On Saturday, October 30, 2021 at 9:31:12 AM UTC-4 jrehwin wrote:


Most DMMs have 10Meg input impedance, so you can put a 10meg
resistor in-series with your meter, and measure double the voltage.


Note that many resistors are rated at only 150V, and aren't suitable
for high voltage service like this.  There are, of course, resistors
with sufficient voltage specifications, but they're less likely to
be found in your junk box.

- John

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Re: [neonixie-l] Scope Clock SC200C

[Mac Doktor]

> On Oct 30, 2021, at 6:17 PM, Tom Harris  wrote:
> 
> Which is why you use a string of them in series for this sort of thing.

My old HV scope probe has a resistor in it that's several inches long. It's 
rated something like 40kV and several rings in front of the handle to prevent 
arc-over. Must be for checking the high tension in a TV set. I also have a 
small laser power supply that I bought as a kit at a hamfest around '93. The 
bleeder on it is almost as long. 

Like all laser PS kits I've seen the design is rather dodgy. The power 
transistor is only a TO-220 and the kit included a flimsy snap-on heat sink 
that gets too hot to touch in about fifteen seconds. I asked the seller about 
it and he said not to worry as the transistor was running within its heat spec. 
Right. When I can smell a transistor from across the room it's probably too hot.

I retrofitted it with the most enormous vertical TO-220 heat sink I could find 
and even that got too hot to touch after a few minutes. Switching out the 0.5mW 
tube that came with the kit with a 0.25mW finally solved the problem.


> With appropriate insulation, I saw glass tube used in a physics lab.

You can always fill the tube with transformer oil. Preferably the kind that 
doesn't have PCBs in it.


Terry Bowman, KA4HJH
"The Mac Doctor"

Q: Should car stereo speakers be pointed to the rear for more thrust or up for 
more traction?

A. On long trips, the 20- to 30% improvement in gas mileage you might get with 
speakers pointing to the rear is certainly worthwhile. On the other hand, if 
you drive on snow or ice, the extra traction of speakers pointing upward gives 
you added control.

Don Lancaster

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Re: [neonixie-l] Scope Clock SC200C

[Tom Harris]

Which is why you use a string of them in series for this sort of thing.
With appropriate insulation, I saw glass tube used in a physics lab.

On Sun, 31 Oct. 2021, 12:31 am 'John Rehwinkel' via neonixie-l, <
neonixie-l@googlegroups.com> wrote:

> Most DMMs have 10Meg input impedance, so you can put a 10meg resistor
> in-series with your meter, and measure double the voltage.
>
>
> Note that many resistors are rated at only 150V, and aren't suitable for
> high voltage service like this.  There are, of course, resistors with
> sufficient voltage specifications, but they're less likely to be found in
> your junk box.
>
> - John
>
> --
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> "neonixie-l" group.
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> 
> .
>

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Re: [neonixie-l] Scope Clock SC200C

[GEK]

Success!!!  I really appreciate all of the help from Tristan and others.  
Nice to have my clock back. 

Turns out the trace from blanking from pin 9 of the 74HC74 takes a very 
long route around the edge of the board in reaching pin 2 of U17 (6N137).  
There was a small defect in the copper trace that must have failed over 
time.  I was checking the blanking signal at the 74HC74 and missed checking 
the final connection to the 6N137. 

The point about resistor voltage ratings is a good one, I often work with 
tube gear where this is an issue.

The CRT is a 3RP1A btw.  They've become pricey but fortunately seem to have 
a long lifespan.  
On Saturday, October 30, 2021 at 9:31:12 AM UTC-4 jrehwin wrote:

> Most DMMs have 10Meg input impedance, so you can put a 10meg resistor 
> in-series with your meter, and measure double the voltage.
>
>
> Note that many resistors are rated at only 150V, and aren't suitable for 
> high voltage service like this.  There are, of course, resistors with 
> sufficient voltage specifications, but they're less likely to be found in 
> your junk box.
>
> - John
>
>

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Re: [neonixie-l] Scope Clock SC200C

['John Rehwinkel' via neonixie-l]

> Most DMMs have 10Meg input impedance, so you can put a 10meg resistor 
> in-series with your meter, and measure double the voltage.

Note that many resistors are rated at only 150V, and aren't suitable for high 
voltage service like this.  There are, of course, resistors with sufficient 
voltage specifications, but they're less likely to be found in your junk box.

- John

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Re: [neonixie-l] Scope Clock SC200C

[Tristan]

Given how far you have gone I'd lift pin 2 of U17 (leaving it unconnected) 
and measure the grid voltage. Then connect PIn 2 of U17 to POS5D and 
measure it again. The voltage should be more positive with the pin 
connected to POS5D. That would answer one and for all if the grid control 
is functional. It would also help to know which CRT model you have.
On Thursday, October 28, 2021 at 12:39:19 PM UTC+10 GEK wrote:

> I'm getting approximately:
> Astig +124v
> Focus/A2  -852v
> Cathode/Bright-1210v
> Grid   -1262v
>
> The manual suggests that the Brightness has about -1300v, focus about 
> -900v and Astig +300v
> I can adjust the Astig from 0 - 240 but the image is sharpest at 124v.
>
> - Gary
>
> On Wednesday, October 27, 2021 at 10:48:16 AM UTC-4 GEK wrote:
>
>> I probably do have a 10meg resistor down in my cellar, time to dig.  I 
>> wasn't sure if I'd need to create an actual voltage divider with 2 
>> resistors/ground wire so that's helpful.  I'd hate to destroy a Fluke...
>>
>> On Wednesday, October 27, 2021 at 1:06:19 AM UTC-4 gregebert wrote:
>>
>>> Most DMMs have 10Meg input impedance, so you can put a 10meg resistor 
>>> in-series with your meter, and measure double the voltage. It wont be 
>>> exact, but pretty close. If you really need an exact measurement, then 
>>> measure a stable lower voltage without the resistor, then again with it. 
>>> Dividing those 2 measurements will give you a ratio close to 2.0, and you 
>>> can use that when measuring your high voltage.
>>>
>>>
>>> On Tuesday, October 26, 2021 at 8:40:54 PM UTC-7 GEK wrote:
>>>
 Thanks everyone for the hints, I'll look more closely at the HV - I'm a 
 bit shy about measuring as I don't have a meter that will go to -1300v for 
 the bright.

 - Gary

 On Tuesday, October 26, 2021 at 3:17:49 PM UTC-4 Bartek Ogryz wrote:

> I'm not familiar with that project and that circuit, but based on my 
> experience in CRT TV repairs, if you have a proper blanking signal, 
> something must be wrong with HV as Tristan said.
> Grid1 - negative voltage on this grid allows electrons to flow 
> (brighter picture), 0V blocks them (darkness). This grid can be driven by 
> the blanking signal,
> Grid2 - is the screen grid, high voltage accelerates the electrons and 
> brightens the screen. If that voltage is too high, it can "force" 
> electrons 
> to flow, regardless of the Grid1 voltage.
> Chceck the main power supply first - if it's voltage is too high, all 
> HV voltages will also be too high.
> wtorek, 26 października 2021 o 05:02:21 UTC+2 Tristan napisał(a):
>
>> The brightness pot needing to be turned right up still suggests that 
>> you have a problem with grid voltage control. I'd expect to see some 
>> higher 
>> frequencies much higher than 60Hz on the BLNK- signal as well though. 
>> I'd 
>> be surprised if the problem was in the supply sections for the cathode 
>> or 
>> anode given that it is mostly working in your photo but there could be 
>> an 
>> issue with the specific section of the supply dedicated to the grid and 
>> it 
>> is referenced to the cathode. Although you have now replaced most of the 
>> potentially offending components unless you have an open winding on the 
>> transformer. You could check the resistance across pins 4,5 and 6 of the 
>> transformer. I'd expect them all to read fairly low.
>> On Tuesday, October 26, 2021 at 10:20:26 AM UTC+10 GEK wrote:
>>
>>> Ok, so I'm stumped (again)...
>>>
>>> I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
>>> R67, F68, R69, R70 and R71 measure correctly in circuit.
>>> I've confirmed pulsing on the BLNK- signal at 60hz
>>> I've also swapped U5 (74HC74) and U4 (74HC151).
>>> I've swapped the CRT.
>>>
>>> Curiously I need to have the Bright potentiometer (R11) at maximum 
>>> to get an image.
>>> Could something in the High Voltage Supply be causing problems with 
>>> the blanking?
>>>
>>> On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:
>>>
 Hah yes. I have one of its brethren that is even more 'eclectic'.

 On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:

>
> That may just be one of the worst PCB layouts I've ever seen.
> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin 
> wrote:
>
>> Here's a simple one
>>
>> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>>
>>
>>
>>
>>
>> ~
>> *mcve...@gmail.com*
>>
>>
>> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>>
>>> Will do, Hopefully parts will be here by Friday.  I may try and 
>>> shotgun D35-38 

Re: [neonixie-l] Scope Clock SC200C

[GEK]

I'm getting approximately:
Astig +124v
Focus/A2  -852v
Cathode/Bright-1210v
Grid   -1262v

The manual suggests that the Brightness has about -1300v, focus about -900v 
and Astig +300v
I can adjust the Astig from 0 - 240 but the image is sharpest at 124v.

- Gary

On Wednesday, October 27, 2021 at 10:48:16 AM UTC-4 GEK wrote:

> I probably do have a 10meg resistor down in my cellar, time to dig.  I 
> wasn't sure if I'd need to create an actual voltage divider with 2 
> resistors/ground wire so that's helpful.  I'd hate to destroy a Fluke...
>
> On Wednesday, October 27, 2021 at 1:06:19 AM UTC-4 gregebert wrote:
>
>> Most DMMs have 10Meg input impedance, so you can put a 10meg resistor 
>> in-series with your meter, and measure double the voltage. It wont be 
>> exact, but pretty close. If you really need an exact measurement, then 
>> measure a stable lower voltage without the resistor, then again with it. 
>> Dividing those 2 measurements will give you a ratio close to 2.0, and you 
>> can use that when measuring your high voltage.
>>
>>
>> On Tuesday, October 26, 2021 at 8:40:54 PM UTC-7 GEK wrote:
>>
>>> Thanks everyone for the hints, I'll look more closely at the HV - I'm a 
>>> bit shy about measuring as I don't have a meter that will go to -1300v for 
>>> the bright.
>>>
>>> - Gary
>>>
>>> On Tuesday, October 26, 2021 at 3:17:49 PM UTC-4 Bartek Ogryz wrote:
>>>
 I'm not familiar with that project and that circuit, but based on my 
 experience in CRT TV repairs, if you have a proper blanking signal, 
 something must be wrong with HV as Tristan said.
 Grid1 - negative voltage on this grid allows electrons to flow 
 (brighter picture), 0V blocks them (darkness). This grid can be driven by 
 the blanking signal,
 Grid2 - is the screen grid, high voltage accelerates the electrons and 
 brightens the screen. If that voltage is too high, it can "force" 
 electrons 
 to flow, regardless of the Grid1 voltage.
 Chceck the main power supply first - if it's voltage is too high, all 
 HV voltages will also be too high.
 wtorek, 26 października 2021 o 05:02:21 UTC+2 Tristan napisał(a):

> The brightness pot needing to be turned right up still suggests that 
> you have a problem with grid voltage control. I'd expect to see some 
> higher 
> frequencies much higher than 60Hz on the BLNK- signal as well though. I'd 
> be surprised if the problem was in the supply sections for the cathode or 
> anode given that it is mostly working in your photo but there could be an 
> issue with the specific section of the supply dedicated to the grid and 
> it 
> is referenced to the cathode. Although you have now replaced most of the 
> potentially offending components unless you have an open winding on the 
> transformer. You could check the resistance across pins 4,5 and 6 of the 
> transformer. I'd expect them all to read fairly low.
> On Tuesday, October 26, 2021 at 10:20:26 AM UTC+10 GEK wrote:
>
>> Ok, so I'm stumped (again)...
>>
>> I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
>> R67, F68, R69, R70 and R71 measure correctly in circuit.
>> I've confirmed pulsing on the BLNK- signal at 60hz
>> I've also swapped U5 (74HC74) and U4 (74HC151).
>> I've swapped the CRT.
>>
>> Curiously I need to have the Bright potentiometer (R11) at maximum to 
>> get an image.
>> Could something in the High Voltage Supply be causing problems with 
>> the blanking?
>>
>> On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:
>>
>>> Hah yes. I have one of its brethren that is even more 'eclectic'.
>>>
>>> On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:
>>>

 That may just be one of the worst PCB layouts I've ever seen.
 On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin 
 wrote:

> Here's a simple one
>
> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>
>
>
>
>
> ~
> *mcve...@gmail.com*
>
>
> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>
>> Will do, Hopefully parts will be here by Friday.  I may try and 
>> shotgun D35-38 and C52-53 before then as I should have spares around 
>> here.
>>
>> Finger's crossed!
>>
>> - Gary
>>
>> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>>
>>> Hi Gary,
>>>
>>> That's a bit odd. While I'm no EE I would have expected that 
>>> removing U17 would have blanked the display if the rest of the 
>>> circuit was 
>>> working correctly. It looks Q13 should be conducting without U17 
>>> fitted and 
>>> 

Re: [neonixie-l] Scope Clock SC200C

[GEK]

I probably do have a 10meg resistor down in my cellar, time to dig.  I 
wasn't sure if I'd need to create an actual voltage divider with 2 
resistors/ground wire so that's helpful.  I'd hate to destroy a Fluke...

On Wednesday, October 27, 2021 at 1:06:19 AM UTC-4 gregebert wrote:

> Most DMMs have 10Meg input impedance, so you can put a 10meg resistor 
> in-series with your meter, and measure double the voltage. It wont be 
> exact, but pretty close. If you really need an exact measurement, then 
> measure a stable lower voltage without the resistor, then again with it. 
> Dividing those 2 measurements will give you a ratio close to 2.0, and you 
> can use that when measuring your high voltage.
>
>
> On Tuesday, October 26, 2021 at 8:40:54 PM UTC-7 GEK wrote:
>
>> Thanks everyone for the hints, I'll look more closely at the HV - I'm a 
>> bit shy about measuring as I don't have a meter that will go to -1300v for 
>> the bright.
>>
>> - Gary
>>
>> On Tuesday, October 26, 2021 at 3:17:49 PM UTC-4 Bartek Ogryz wrote:
>>
>>> I'm not familiar with that project and that circuit, but based on my 
>>> experience in CRT TV repairs, if you have a proper blanking signal, 
>>> something must be wrong with HV as Tristan said.
>>> Grid1 - negative voltage on this grid allows electrons to flow (brighter 
>>> picture), 0V blocks them (darkness). This grid can be driven by the 
>>> blanking signal,
>>> Grid2 - is the screen grid, high voltage accelerates the electrons and 
>>> brightens the screen. If that voltage is too high, it can "force" electrons 
>>> to flow, regardless of the Grid1 voltage.
>>> Chceck the main power supply first - if it's voltage is too high, all HV 
>>> voltages will also be too high.
>>> wtorek, 26 października 2021 o 05:02:21 UTC+2 Tristan napisał(a):
>>>
 The brightness pot needing to be turned right up still suggests that 
 you have a problem with grid voltage control. I'd expect to see some 
 higher 
 frequencies much higher than 60Hz on the BLNK- signal as well though. I'd 
 be surprised if the problem was in the supply sections for the cathode or 
 anode given that it is mostly working in your photo but there could be an 
 issue with the specific section of the supply dedicated to the grid and it 
 is referenced to the cathode. Although you have now replaced most of the 
 potentially offending components unless you have an open winding on the 
 transformer. You could check the resistance across pins 4,5 and 6 of the 
 transformer. I'd expect them all to read fairly low.
 On Tuesday, October 26, 2021 at 10:20:26 AM UTC+10 GEK wrote:

> Ok, so I'm stumped (again)...
>
> I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
> R67, F68, R69, R70 and R71 measure correctly in circuit.
> I've confirmed pulsing on the BLNK- signal at 60hz
> I've also swapped U5 (74HC74) and U4 (74HC151).
> I've swapped the CRT.
>
> Curiously I need to have the Bright potentiometer (R11) at maximum to 
> get an image.
> Could something in the High Voltage Supply be causing problems with 
> the blanking?
>
> On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:
>
>> Hah yes. I have one of its brethren that is even more 'eclectic'.
>>
>> On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:
>>
>>>
>>> That may just be one of the worst PCB layouts I've ever seen.
>>> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin 
>>> wrote:
>>>
 Here's a simple one

 https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/





 ~
 *mcve...@gmail.com*


 On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:

> Will do, Hopefully parts will be here by Friday.  I may try and 
> shotgun D35-38 and C52-53 before then as I should have spares around 
> here.
>
> Finger's crossed!
>
> - Gary
>
> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>
>> Hi Gary,
>>
>> That's a bit odd. While I'm no EE I would have expected that 
>> removing U17 would have blanked the display if the rest of the 
>> circuit was 
>> working correctly. It looks Q13 should be conducting without U17 
>> fitted and 
>> the grid should become more negative with respect to the cathode to 
>> ensure 
>> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>>
>> - Tristan
>>
>> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>>
>>> Tristan -
>>>
>>> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and 
>>> I swapped Q13 without any change.  I also socketed 

Re: [neonixie-l] Scope Clock SC200C

[gregebert]

Most DMMs have 10Meg input impedance, so you can put a 10meg resistor 
in-series with your meter, and measure double the voltage. It wont be 
exact, but pretty close. If you really need an exact measurement, then 
measure a stable lower voltage without the resistor, then again with it. 
Dividing those 2 measurements will give you a ratio close to 2.0, and you 
can use that when measuring your high voltage.


On Tuesday, October 26, 2021 at 8:40:54 PM UTC-7 GEK wrote:

> Thanks everyone for the hints, I'll look more closely at the HV - I'm a 
> bit shy about measuring as I don't have a meter that will go to -1300v for 
> the bright.
>
> - Gary
>
> On Tuesday, October 26, 2021 at 3:17:49 PM UTC-4 Bartek Ogryz wrote:
>
>> I'm not familiar with that project and that circuit, but based on my 
>> experience in CRT TV repairs, if you have a proper blanking signal, 
>> something must be wrong with HV as Tristan said.
>> Grid1 - negative voltage on this grid allows electrons to flow (brighter 
>> picture), 0V blocks them (darkness). This grid can be driven by the 
>> blanking signal,
>> Grid2 - is the screen grid, high voltage accelerates the electrons and 
>> brightens the screen. If that voltage is too high, it can "force" electrons 
>> to flow, regardless of the Grid1 voltage.
>> Chceck the main power supply first - if it's voltage is too high, all HV 
>> voltages will also be too high.
>> wtorek, 26 października 2021 o 05:02:21 UTC+2 Tristan napisał(a):
>>
>>> The brightness pot needing to be turned right up still suggests that you 
>>> have a problem with grid voltage control. I'd expect to see some higher 
>>> frequencies much higher than 60Hz on the BLNK- signal as well though. I'd 
>>> be surprised if the problem was in the supply sections for the cathode or 
>>> anode given that it is mostly working in your photo but there could be an 
>>> issue with the specific section of the supply dedicated to the grid and it 
>>> is referenced to the cathode. Although you have now replaced most of the 
>>> potentially offending components unless you have an open winding on the 
>>> transformer. You could check the resistance across pins 4,5 and 6 of the 
>>> transformer. I'd expect them all to read fairly low.
>>> On Tuesday, October 26, 2021 at 10:20:26 AM UTC+10 GEK wrote:
>>>
 Ok, so I'm stumped (again)...

 I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
 R67, F68, R69, R70 and R71 measure correctly in circuit.
 I've confirmed pulsing on the BLNK- signal at 60hz
 I've also swapped U5 (74HC74) and U4 (74HC151).
 I've swapped the CRT.

 Curiously I need to have the Bright potentiometer (R11) at maximum to 
 get an image.
 Could something in the High Voltage Supply be causing problems with the 
 blanking?

 On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:

> Hah yes. I have one of its brethren that is even more 'eclectic'.
>
> On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:
>
>>
>> That may just be one of the worst PCB layouts I've ever seen.
>> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin 
>> wrote:
>>
>>> Here's a simple one
>>>
>>> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>>>
>>>
>>>
>>>
>>>
>>> ~
>>> *mcve...@gmail.com*
>>>
>>>
>>> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>>>
 Will do, Hopefully parts will be here by Friday.  I may try and 
 shotgun D35-38 and C52-53 before then as I should have spares around 
 here.

 Finger's crossed!

 - Gary

 On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:

> Hi Gary,
>
> That's a bit odd. While I'm no EE I would have expected that 
> removing U17 would have blanked the display if the rest of the 
> circuit was 
> working correctly. It looks Q13 should be conducting without U17 
> fitted and 
> the grid should become more negative with respect to the cathode to 
> ensure 
> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>
> - Tristan
>
> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>
>> Tristan -
>>
>> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and 
>> I swapped Q13 without any change.  I also socketed U17 (6N137) while 
>> waiting for a replacement to arrive.  Removing U17 from the circuit 
>> leaves 
>> the display unchanged, so it does appear that the blanking circuit 
>> is the 
>> culprit.
>>
>> I'll swap U17 once it arrives - and if that doesn't fix things 
>> start shotgunning the passives.  
>>
>> Thanks again for 

Re: [neonixie-l] Scope Clock SC200C

[GEK]

Thanks everyone for the hints, I'll look more closely at the HV - I'm a bit 
shy about measuring as I don't have a meter that will go to -1300v for the 
bright.

- Gary

On Tuesday, October 26, 2021 at 3:17:49 PM UTC-4 Bartek Ogryz wrote:

> I'm not familiar with that project and that circuit, but based on my 
> experience in CRT TV repairs, if you have a proper blanking signal, 
> something must be wrong with HV as Tristan said.
> Grid1 - negative voltage on this grid allows electrons to flow (brighter 
> picture), 0V blocks them (darkness). This grid can be driven by the 
> blanking signal,
> Grid2 - is the screen grid, high voltage accelerates the electrons and 
> brightens the screen. If that voltage is too high, it can "force" electrons 
> to flow, regardless of the Grid1 voltage.
> Chceck the main power supply first - if it's voltage is too high, all HV 
> voltages will also be too high.
> wtorek, 26 października 2021 o 05:02:21 UTC+2 Tristan napisał(a):
>
>> The brightness pot needing to be turned right up still suggests that you 
>> have a problem with grid voltage control. I'd expect to see some higher 
>> frequencies much higher than 60Hz on the BLNK- signal as well though. I'd 
>> be surprised if the problem was in the supply sections for the cathode or 
>> anode given that it is mostly working in your photo but there could be an 
>> issue with the specific section of the supply dedicated to the grid and it 
>> is referenced to the cathode. Although you have now replaced most of the 
>> potentially offending components unless you have an open winding on the 
>> transformer. You could check the resistance across pins 4,5 and 6 of the 
>> transformer. I'd expect them all to read fairly low.
>> On Tuesday, October 26, 2021 at 10:20:26 AM UTC+10 GEK wrote:
>>
>>> Ok, so I'm stumped (again)...
>>>
>>> I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
>>> R67, F68, R69, R70 and R71 measure correctly in circuit.
>>> I've confirmed pulsing on the BLNK- signal at 60hz
>>> I've also swapped U5 (74HC74) and U4 (74HC151).
>>> I've swapped the CRT.
>>>
>>> Curiously I need to have the Bright potentiometer (R11) at maximum to 
>>> get an image.
>>> Could something in the High Voltage Supply be causing problems with the 
>>> blanking?
>>>
>>> On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:
>>>
 Hah yes. I have one of its brethren that is even more 'eclectic'.

 On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:

>
> That may just be one of the worst PCB layouts I've ever seen.
> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:
>
>> Here's a simple one
>>
>> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>>
>>
>>
>>
>>
>> ~
>> *mcve...@gmail.com*
>>
>>
>> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>>
>>> Will do, Hopefully parts will be here by Friday.  I may try and 
>>> shotgun D35-38 and C52-53 before then as I should have spares around 
>>> here.
>>>
>>> Finger's crossed!
>>>
>>> - Gary
>>>
>>> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>>>
 Hi Gary,

 That's a bit odd. While I'm no EE I would have expected that 
 removing U17 would have blanked the display if the rest of the circuit 
 was 
 working correctly. It looks Q13 should be conducting without U17 
 fitted and 
 the grid should become more negative with respect to the cathode to 
 ensure 
 cutoff. I think you may need to look at the D35-38 and C52 & C53.

 - Tristan

 On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:

> Tristan -
>
> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
> swapped Q13 without any change.  I also socketed U17 (6N137) while 
> waiting 
> for a replacement to arrive.  Removing U17 from the circuit leaves 
> the 
> display unchanged, so it does appear that the blanking circuit is the 
> culprit.
>
> I'll swap U17 once it arrives - and if that doesn't fix things 
> start shotgunning the passives.  
>
> Thanks again for the guidance, very appreciated!
>
> - Gary  
>
> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>
>> Also the voltage between the cathode and the blanking section 
>> should be checked (I.e. the voltage across C51) and R65 and R67 
>> should be 
>> checked (or potentially replaced along with C51 if shotgunning it). 
>> The 
>> rest of the high voltage supply appears to be working.
>>
>> - Tristan
>> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan 

Re: [neonixie-l] Scope Clock SC200C

[Bartek Ogryz]

I'm not familiar with that project and that circuit, but based on my 
experience in CRT TV repairs, if you have a proper blanking signal, 
something must be wrong with HV as Tristan said.
Grid1 - negative voltage on this grid allows electrons to flow (brighter 
picture), 0V blocks them (darkness). This grid can be driven by the 
blanking signal,
Grid2 - is the screen grid, high voltage accelerates the electrons and 
brightens the screen. If that voltage is too high, it can "force" electrons 
to flow, regardless of the Grid1 voltage.
Chceck the main power supply first - if it's voltage is too high, all HV 
voltages will also be too high.
wtorek, 26 października 2021 o 05:02:21 UTC+2 Tristan napisał(a):

> The brightness pot needing to be turned right up still suggests that you 
> have a problem with grid voltage control. I'd expect to see some higher 
> frequencies much higher than 60Hz on the BLNK- signal as well though. I'd 
> be surprised if the problem was in the supply sections for the cathode or 
> anode given that it is mostly working in your photo but there could be an 
> issue with the specific section of the supply dedicated to the grid and it 
> is referenced to the cathode. Although you have now replaced most of the 
> potentially offending components unless you have an open winding on the 
> transformer. You could check the resistance across pins 4,5 and 6 of the 
> transformer. I'd expect them all to read fairly low.
> On Tuesday, October 26, 2021 at 10:20:26 AM UTC+10 GEK wrote:
>
>> Ok, so I'm stumped (again)...
>>
>> I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
>> R67, F68, R69, R70 and R71 measure correctly in circuit.
>> I've confirmed pulsing on the BLNK- signal at 60hz
>> I've also swapped U5 (74HC74) and U4 (74HC151).
>> I've swapped the CRT.
>>
>> Curiously I need to have the Bright potentiometer (R11) at maximum to get 
>> an image.
>> Could something in the High Voltage Supply be causing problems with the 
>> blanking?
>>
>> On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:
>>
>>> Hah yes. I have one of its brethren that is even more 'eclectic'.
>>>
>>> On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:
>>>

 That may just be one of the worst PCB layouts I've ever seen.
 On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:

> Here's a simple one
>
> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>
>
>
>
>
> ~
> *mcve...@gmail.com*
>
>
> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>
>> Will do, Hopefully parts will be here by Friday.  I may try and 
>> shotgun D35-38 and C52-53 before then as I should have spares around 
>> here.
>>
>> Finger's crossed!
>>
>> - Gary
>>
>> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>>
>>> Hi Gary,
>>>
>>> That's a bit odd. While I'm no EE I would have expected that 
>>> removing U17 would have blanked the display if the rest of the circuit 
>>> was 
>>> working correctly. It looks Q13 should be conducting without U17 fitted 
>>> and 
>>> the grid should become more negative with respect to the cathode to 
>>> ensure 
>>> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>>>
>>> - Tristan
>>>
>>> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>>>
 Tristan -

 Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
 swapped Q13 without any change.  I also socketed U17 (6N137) while 
 waiting 
 for a replacement to arrive.  Removing U17 from the circuit leaves the 
 display unchanged, so it does appear that the blanking circuit is the 
 culprit.

 I'll swap U17 once it arrives - and if that doesn't fix things 
 start shotgunning the passives.  

 Thanks again for the guidance, very appreciated!

 - Gary  

 On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:

> Also the voltage between the cathode and the blanking section 
> should be checked (I.e. the voltage across C51) and R65 and R67 
> should be 
> checked (or potentially replaced along with C51 if shotgunning it). 
> The 
> rest of the high voltage supply appears to be working.
>
> - Tristan
> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>
>> I agree. The blanking is not working and as a result the beam is 
>> also faintly visible as it moves quickly between the characters as 
>> well 
>> drawing the arcs. It would be a good idea to check the BLNK signal 
>> on a 
>> scope and at least see that is is toggling but my money would be on 
>> 

Re: [neonixie-l] Scope Clock SC200C

[Tristan]

The brightness pot needing to be turned right up still suggests that you 
have a problem with grid voltage control. I'd expect to see some higher 
frequencies much higher than 60Hz on the BLNK- signal as well though. I'd 
be surprised if the problem was in the supply sections for the cathode or 
anode given that it is mostly working in your photo but there could be an 
issue with the specific section of the supply dedicated to the grid and it 
is referenced to the cathode. Although you have now replaced most of the 
potentially offending components unless you have an open winding on the 
transformer. You could check the resistance across pins 4,5 and 6 of the 
transformer. I'd expect them all to read fairly low.
On Tuesday, October 26, 2021 at 10:20:26 AM UTC+10 GEK wrote:

> Ok, so I'm stumped (again)...
>
> I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
> R67, F68, R69, R70 and R71 measure correctly in circuit.
> I've confirmed pulsing on the BLNK- signal at 60hz
> I've also swapped U5 (74HC74) and U4 (74HC151).
> I've swapped the CRT.
>
> Curiously I need to have the Bright potentiometer (R11) at maximum to get 
> an image.
> Could something in the High Voltage Supply be causing problems with the 
> blanking?
>
> On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:
>
>> Hah yes. I have one of its brethren that is even more 'eclectic'.
>>
>> On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:
>>
>>>
>>> That may just be one of the worst PCB layouts I've ever seen.
>>> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:
>>>
 Here's a simple one

 https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/





 ~
 *mcve...@gmail.com*


 On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:

> Will do, Hopefully parts will be here by Friday.  I may try and 
> shotgun D35-38 and C52-53 before then as I should have spares around here.
>
> Finger's crossed!
>
> - Gary
>
> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>
>> Hi Gary,
>>
>> That's a bit odd. While I'm no EE I would have expected that removing 
>> U17 would have blanked the display if the rest of the circuit was 
>> working 
>> correctly. It looks Q13 should be conducting without U17 fitted and the 
>> grid should become more negative with respect to the cathode to ensure 
>> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>>
>> - Tristan
>>
>> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>>
>>> Tristan -
>>>
>>> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
>>> swapped Q13 without any change.  I also socketed U17 (6N137) while 
>>> waiting 
>>> for a replacement to arrive.  Removing U17 from the circuit leaves the 
>>> display unchanged, so it does appear that the blanking circuit is the 
>>> culprit.
>>>
>>> I'll swap U17 once it arrives - and if that doesn't fix things start 
>>> shotgunning the passives.  
>>>
>>> Thanks again for the guidance, very appreciated!
>>>
>>> - Gary  
>>>
>>> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>>>
 Also the voltage between the cathode and the blanking section 
 should be checked (I.e. the voltage across C51) and R65 and R67 should 
 be 
 checked (or potentially replaced along with C51 if shotgunning it). 
 The 
 rest of the high voltage supply appears to be working.

 - Tristan
 On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:

> I agree. The blanking is not working and as a result the beam is 
> also faintly visible as it moves quickly between the characters as 
> well 
> drawing the arcs. It would be a good idea to check the BLNK signal on 
> a 
> scope and at least see that is is toggling but my money would be on 
> the 
> analogue blanking section. Given the other side of the optoisolator 
> in the 
> blanking section is at a fairly high negative voltage potential (as 
> this 
> reduces the need for the deflection amps to handle higher voltages) 
> you 
> will need to be careful when probing around there but I would start 
> by 
> checking the voltages across C54 and C55 (as long as you are 
> confident 
> doing so safely with the HV potential to ground). The correct 
> voltages 
> aren't specified on the schematic but they will be based on the grid 
> cutoff 
> voltage of the tube. If you wanted to avoid probing while the clock 
> is on 
> I'd be inclined to shotgun replace that section starting with the 
> power 

Re: [neonixie-l] Scope Clock SC200C

[gregebert]

I dont have the same exact scope-clock, but with mine the intensity, focus, 
and astigmatism adjustments all interplay with eachother. Mine uses an 
8SJ31J tube, and there is a test-point where you can verify the HV is 
correct. It should measure 300V. 

On Monday, October 25, 2021 at 5:20:26 PM UTC-7 GEK wrote:

> Ok, so I'm stumped (again)...
>
> I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
> R67, F68, R69, R70 and R71 measure correctly in circuit.
> I've confirmed pulsing on the BLNK- signal at 60hz
> I've also swapped U5 (74HC74) and U4 (74HC151).
> I've swapped the CRT.
>
> Curiously I need to have the Bright potentiometer (R11) at maximum to get 
> an image.
> Could something in the High Voltage Supply be causing problems with the 
> blanking?
>
> On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:
>
>> Hah yes. I have one of its brethren that is even more 'eclectic'.
>>
>> On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:
>>
>>>
>>> That may just be one of the worst PCB layouts I've ever seen.
>>> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:
>>>
 Here's a simple one

 https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/





 ~
 *mcve...@gmail.com*


 On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:

> Will do, Hopefully parts will be here by Friday.  I may try and 
> shotgun D35-38 and C52-53 before then as I should have spares around here.
>
> Finger's crossed!
>
> - Gary
>
> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>
>> Hi Gary,
>>
>> That's a bit odd. While I'm no EE I would have expected that removing 
>> U17 would have blanked the display if the rest of the circuit was 
>> working 
>> correctly. It looks Q13 should be conducting without U17 fitted and the 
>> grid should become more negative with respect to the cathode to ensure 
>> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>>
>> - Tristan
>>
>> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>>
>>> Tristan -
>>>
>>> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
>>> swapped Q13 without any change.  I also socketed U17 (6N137) while 
>>> waiting 
>>> for a replacement to arrive.  Removing U17 from the circuit leaves the 
>>> display unchanged, so it does appear that the blanking circuit is the 
>>> culprit.
>>>
>>> I'll swap U17 once it arrives - and if that doesn't fix things start 
>>> shotgunning the passives.  
>>>
>>> Thanks again for the guidance, very appreciated!
>>>
>>> - Gary  
>>>
>>> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>>>
 Also the voltage between the cathode and the blanking section 
 should be checked (I.e. the voltage across C51) and R65 and R67 should 
 be 
 checked (or potentially replaced along with C51 if shotgunning it). 
 The 
 rest of the high voltage supply appears to be working.

 - Tristan
 On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:

> I agree. The blanking is not working and as a result the beam is 
> also faintly visible as it moves quickly between the characters as 
> well 
> drawing the arcs. It would be a good idea to check the BLNK signal on 
> a 
> scope and at least see that is is toggling but my money would be on 
> the 
> analogue blanking section. Given the other side of the optoisolator 
> in the 
> blanking section is at a fairly high negative voltage potential (as 
> this 
> reduces the need for the deflection amps to handle higher voltages) 
> you 
> will need to be careful when probing around there but I would start 
> by 
> checking the voltages across C54 and C55 (as long as you are 
> confident 
> doing so safely with the HV potential to ground). The correct 
> voltages 
> aren't specified on the schematic but they will be based on the grid 
> cutoff 
> voltage of the tube. If you wanted to avoid probing while the clock 
> is on 
> I'd be inclined to shotgun replace that section starting with the 
> power 
> supply diodes, caps and Q13 and then U17 and finally the passives and 
> see 
> how you go.
>
> - Tristan
> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
>
>> From what I remember:
>> the characters are generated from circles, ellipses or lines 
>> which in turn are created using sun or cosine waveforms
>> To make a character the beam is blanked for certain 

Re: [neonixie-l] Scope Clock SC200C

[GEK]

Ok, so I'm stumped (again)...

I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17.  
R67, F68, R69, R70 and R71 measure correctly in circuit.
I've confirmed pulsing on the BLNK- signal at 60hz
I've also swapped U5 (74HC74) and U4 (74HC151).
I've swapped the CRT.

Curiously I need to have the Bright potentiometer (R11) at maximum to get 
an image.
Could something in the High Voltage Supply be causing problems with the 
blanking?

On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote:

> Hah yes. I have one of its brethren that is even more 'eclectic'.
>
> On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:
>
>>
>> That may just be one of the worst PCB layouts I've ever seen.
>> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:
>>
>>> Here's a simple one
>>>
>>> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>>>
>>>
>>>
>>>
>>>
>>> ~
>>> *mcve...@gmail.com*
>>>
>>>
>>> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>>>
 Will do, Hopefully parts will be here by Friday.  I may try and shotgun 
 D35-38 and C52-53 before then as I should have spares around here.

 Finger's crossed!

 - Gary

 On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:

> Hi Gary,
>
> That's a bit odd. While I'm no EE I would have expected that removing 
> U17 would have blanked the display if the rest of the circuit was working 
> correctly. It looks Q13 should be conducting without U17 fitted and the 
> grid should become more negative with respect to the cathode to ensure 
> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>
> - Tristan
>
> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>
>> Tristan -
>>
>> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
>> swapped Q13 without any change.  I also socketed U17 (6N137) while 
>> waiting 
>> for a replacement to arrive.  Removing U17 from the circuit leaves the 
>> display unchanged, so it does appear that the blanking circuit is the 
>> culprit.
>>
>> I'll swap U17 once it arrives - and if that doesn't fix things start 
>> shotgunning the passives.  
>>
>> Thanks again for the guidance, very appreciated!
>>
>> - Gary  
>>
>> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>>
>>> Also the voltage between the cathode and the blanking section should 
>>> be checked (I.e. the voltage across C51) and R65 and R67 should be 
>>> checked 
>>> (or potentially replaced along with C51 if shotgunning it). The rest of 
>>> the 
>>> high voltage supply appears to be working.
>>>
>>> - Tristan
>>> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>>>
 I agree. The blanking is not working and as a result the beam is 
 also faintly visible as it moves quickly between the characters as 
 well 
 drawing the arcs. It would be a good idea to check the BLNK signal on 
 a 
 scope and at least see that is is toggling but my money would be on 
 the 
 analogue blanking section. Given the other side of the optoisolator in 
 the 
 blanking section is at a fairly high negative voltage potential (as 
 this 
 reduces the need for the deflection amps to handle higher voltages) 
 you 
 will need to be careful when probing around there but I would start by 
 checking the voltages across C54 and C55 (as long as you are confident 
 doing so safely with the HV potential to ground). The correct voltages 
 aren't specified on the schematic but they will be based on the grid 
 cutoff 
 voltage of the tube. If you wanted to avoid probing while the clock is 
 on 
 I'd be inclined to shotgun replace that section starting with the 
 power 
 supply diodes, caps and Q13 and then U17 and finally the passives and 
 see 
 how you go.

 - Tristan
 On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:

> From what I remember:
> the characters are generated from circles, ellipses or lines which 
> in turn are created using sun or cosine waveforms
> To make a character the beam is blanked for certain parts eg C is 
> a circle with a bit cut out. 
>
> Looks like the blanking is not working as you’ve got a lot of 
> circles and ellipses there. 
>
> Looks cool though
>
> Cheers
> Ian V
>
> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
>
> 
>
>
> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  
> wrote:
>
> I've now got a stable, but 

Re: [neonixie-l] Scope Clock SC200C

[Paul Andrews]

Hah yes. I have one of its brethren that is even more 'eclectic'.

On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S wrote:

>
> That may just be one of the worst PCB layouts I've ever seen.
> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:
>
>> Here's a simple one
>>
>> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>>
>>
>>
>>
>>
>> ~
>> *mcve...@gmail.com*
>>
>>
>> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>>
>>> Will do, Hopefully parts will be here by Friday.  I may try and shotgun 
>>> D35-38 and C52-53 before then as I should have spares around here.
>>>
>>> Finger's crossed!
>>>
>>> - Gary
>>>
>>> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>>>
 Hi Gary,

 That's a bit odd. While I'm no EE I would have expected that removing 
 U17 would have blanked the display if the rest of the circuit was working 
 correctly. It looks Q13 should be conducting without U17 fitted and the 
 grid should become more negative with respect to the cathode to ensure 
 cutoff. I think you may need to look at the D35-38 and C52 & C53.

 - Tristan

 On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:

> Tristan -
>
> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
> swapped Q13 without any change.  I also socketed U17 (6N137) while 
> waiting 
> for a replacement to arrive.  Removing U17 from the circuit leaves the 
> display unchanged, so it does appear that the blanking circuit is the 
> culprit.
>
> I'll swap U17 once it arrives - and if that doesn't fix things start 
> shotgunning the passives.  
>
> Thanks again for the guidance, very appreciated!
>
> - Gary  
>
> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>
>> Also the voltage between the cathode and the blanking section should 
>> be checked (I.e. the voltage across C51) and R65 and R67 should be 
>> checked 
>> (or potentially replaced along with C51 if shotgunning it). The rest of 
>> the 
>> high voltage supply appears to be working.
>>
>> - Tristan
>> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>>
>>> I agree. The blanking is not working and as a result the beam is 
>>> also faintly visible as it moves quickly between the characters as well 
>>> drawing the arcs. It would be a good idea to check the BLNK signal on a 
>>> scope and at least see that is is toggling but my money would be on the 
>>> analogue blanking section. Given the other side of the optoisolator in 
>>> the 
>>> blanking section is at a fairly high negative voltage potential (as 
>>> this 
>>> reduces the need for the deflection amps to handle higher voltages) you 
>>> will need to be careful when probing around there but I would start by 
>>> checking the voltages across C54 and C55 (as long as you are confident 
>>> doing so safely with the HV potential to ground). The correct voltages 
>>> aren't specified on the schematic but they will be based on the grid 
>>> cutoff 
>>> voltage of the tube. If you wanted to avoid probing while the clock is 
>>> on 
>>> I'd be inclined to shotgun replace that section starting with the power 
>>> supply diodes, caps and Q13 and then U17 and finally the passives and 
>>> see 
>>> how you go.
>>>
>>> - Tristan
>>> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
>>>
 From what I remember:
 the characters are generated from circles, ellipses or lines which 
 in turn are created using sun or cosine waveforms
 To make a character the beam is blanked for certain parts eg C is a 
 circle with a bit cut out. 

 Looks like the blanking is not working as you’ve got a lot of 
 circles and ellipses there. 

 Looks cool though

 Cheers
 Ian V

 On 19 Oct 2021, at 06:08, Mac Doktor  wrote:

 


 On Oct 18, 2021, at 7:53 PM, Gary Kaufman  
 wrote:

 I've now got a stable, but scrambled display (see pic's).  I think 
 I have a problem with the shape generators but would appreciate any 
 help or 
 suggestions you could offer.


 Nah, that's just Cyrillic Neu Sans.


 Terry Bowman, KA4HJH
 "The Mac Doctor"

 "If only you could see what I've seen with your eyes."—Roy Batty, 
 *Blade 
 Runner*

 -- 
 You received this message because you are subscribed to the Google 
 Groups "neonixie-l" group.

 To unsubscribe from this group and stop receiving emails from it, 
 send an email to 

Re: [neonixie-l] Scope Clock SC200C

[Nicholas Stock]

You can find them directly at Howard's website

http://www.oscilloscopeclocknixiecrt.com/Kit.htm

A rudimentary display, but cheap if you want to go that way. I'll stick to
circle generated graphics (ala Grahame's or David's clocks). Each to
their own.

On Wed, Oct 20, 2021 at 5:32 PM liam bartosiewicz <
liambartosiew...@gmail.com> wrote:

> The acute-angle traces give it character
>
> On Oct 20, 2021, at 5:04 PM, Terry S  wrote:
>
> 
> That may just be one of the worst PCB layouts I've ever seen.
> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:
>
>> Here's a simple one
>>
>> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>>
>>
>>
>>
>>
>> ~
>> *mcve...@gmail.com*
>>
>>
>> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>>
>>> Will do, Hopefully parts will be here by Friday.  I may try and shotgun
>>> D35-38 and C52-53 before then as I should have spares around here.
>>>
>>> Finger's crossed!
>>>
>>> - Gary
>>>
>>> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>>>
 Hi Gary,

 That's a bit odd. While I'm no EE I would have expected that removing
 U17 would have blanked the display if the rest of the circuit was working
 correctly. It looks Q13 should be conducting without U17 fitted and the
 grid should become more negative with respect to the cathode to ensure
 cutoff. I think you may need to look at the D35-38 and C52 & C53.

 - Tristan

 On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:

> Tristan -
>
> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I
> swapped Q13 without any change.  I also socketed U17 (6N137) while waiting
> for a replacement to arrive.  Removing U17 from the circuit leaves the
> display unchanged, so it does appear that the blanking circuit is the
> culprit.
>
> I'll swap U17 once it arrives - and if that doesn't fix things start
> shotgunning the passives.
>
> Thanks again for the guidance, very appreciated!
>
> - Gary
>
> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>
>> Also the voltage between the cathode and the blanking section should
>> be checked (I.e. the voltage across C51) and R65 and R67 should be 
>> checked
>> (or potentially replaced along with C51 if shotgunning it). The rest of 
>> the
>> high voltage supply appears to be working.
>>
>> - Tristan
>> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>>
>>> I agree. The blanking is not working and as a result the beam is
>>> also faintly visible as it moves quickly between the characters as well
>>> drawing the arcs. It would be a good idea to check the BLNK signal on a
>>> scope and at least see that is is toggling but my money would be on the
>>> analogue blanking section. Given the other side of the optoisolator in 
>>> the
>>> blanking section is at a fairly high negative voltage potential (as this
>>> reduces the need for the deflection amps to handle higher voltages) you
>>> will need to be careful when probing around there but I would start by
>>> checking the voltages across C54 and C55 (as long as you are confident
>>> doing so safely with the HV potential to ground). The correct voltages
>>> aren't specified on the schematic but they will be based on the grid 
>>> cutoff
>>> voltage of the tube. If you wanted to avoid probing while the clock is 
>>> on
>>> I'd be inclined to shotgun replace that section starting with the power
>>> supply diodes, caps and Q13 and then U17 and finally the passives and 
>>> see
>>> how you go.
>>>
>>> - Tristan
>>> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
>>>
 From what I remember:
 the characters are generated from circles, ellipses or lines which
 in turn are created using sun or cosine waveforms
 To make a character the beam is blanked for certain parts eg C is a
 circle with a bit cut out.

 Looks like the blanking is not working as you’ve got a lot of
 circles and ellipses there.

 Looks cool though

 Cheers
 Ian V

 On 19 Oct 2021, at 06:08, Mac Doktor  wrote:

 


 On Oct 18, 2021, at 7:53 PM, Gary Kaufman 
 wrote:

 I've now got a stable, but scrambled display (see pic's).  I think
 I have a problem with the shape generators but would appreciate any 
 help or
 suggestions you could offer.


 Nah, that's just Cyrillic Neu Sans.


 Terry Bowman, KA4HJH
 "The Mac Doctor"

 "If only you could see what I've seen with your eyes."—Roy Batty, 
 *Blade
 Runner*

Re: [neonixie-l] Scope Clock SC200C

[liam bartosiewicz]

The acute-angle traces give it character

> On Oct 20, 2021, at 5:04 PM, Terry S  wrote:
> 
> 
> That may just be one of the worst PCB layouts I've ever seen.
>> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:
>> Here's a simple one
>> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>> 
>> 
>> 
>> 
>> 
>> ~
>> mcve...@gmail.com
>> 
>> 
>>> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>>> Will do, Hopefully parts will be here by Friday.  I may try and shotgun 
>>> D35-38 and C52-53 before then as I should have spares around here.
>>> 
>>> Finger's crossed!
>>> 
>>> - Gary
>>> 
 On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
 Hi Gary,
 
 That's a bit odd. While I'm no EE I would have expected that removing U17 
 would have blanked the display if the rest of the circuit was working 
 correctly. It looks Q13 should be conducting without U17 fitted and the 
 grid should become more negative with respect to the cathode to ensure 
 cutoff. I think you may need to look at the D35-38 and C52 & C53.
 
 - Tristan
 
> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
> Tristan -
> 
> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
> swapped Q13 without any change.  I also socketed U17 (6N137) while 
> waiting for a replacement to arrive.  Removing U17 from the circuit 
> leaves the display unchanged, so it does appear that the blanking circuit 
> is the culprit.
> 
> I'll swap U17 once it arrives - and if that doesn't fix things start 
> shotgunning the passives.  
> 
> Thanks again for the guidance, very appreciated!
> 
> - Gary  
> 
>> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>> Also the voltage between the cathode and the blanking section should be 
>> checked (I.e. the voltage across C51) and R65 and R67 should be checked 
>> (or potentially replaced along with C51 if shotgunning it). The rest of 
>> the high voltage supply appears to be working.
>> 
>> - Tristan
>>> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>>> I agree. The blanking is not working and as a result the beam is also 
>>> faintly visible as it moves quickly between the characters as well 
>>> drawing the arcs. It would be a good idea to check the BLNK signal on a 
>>> scope and at least see that is is toggling but my money would be on the 
>>> analogue blanking section. Given the other side of the optoisolator in 
>>> the blanking section is at a fairly high negative voltage potential (as 
>>> this reduces the need for the deflection amps to handle higher 
>>> voltages) you will need to be careful when probing around there but I 
>>> would start by checking the voltages across C54 and C55 (as long as you 
>>> are confident doing so safely with the HV potential to ground). The 
>>> correct voltages aren't specified on the schematic but they will be 
>>> based on the grid cutoff voltage of the tube. If you wanted to avoid 
>>> probing while the clock is on I'd be inclined to shotgun replace that 
>>> section starting with the power supply diodes, caps and Q13 and then 
>>> U17 and finally the passives and see how you go.
>>> 
>>> - Tristan
 On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
 From what I remember:
 the characters are generated from circles, ellipses or lines which in 
 turn are created using sun or cosine waveforms
 To make a character the beam is blanked for certain parts eg C is a 
 circle with a bit cut out. 
 
 Looks like the blanking is not working as you’ve got a lot of circles 
 and ellipses there. 
 
 Looks cool though
 
 Cheers
 Ian V
 
>> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
>> 
> 
 
> 
>> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
>> 
>> I've now got a stable, but scrambled display (see pic's).  I think I 
>> have a problem with the shape generators but would appreciate any 
>> help or suggestions you could offer.
> 
> Nah, that's just Cyrillic Neu Sans.
> 
> 
> Terry Bowman, KA4HJH
> "The Mac Doctor"
> 
> "If only you could see what I've seen with your eyes."—Roy Batty, 
> Blade Runner
> 
 
> -- 
> You received this message because you are subscribed to the Google 
> Groups "neonixie-l" group.
 
> To unsubscribe from this group and stop receiving emails from it, 
> send an email to neonixie-l+...@googlegroups.com.
> To view this discussion on the web, visit 
> 

Re: [neonixie-l] Scope Clock SC200C

[Terry S]

That may just be one of the worst PCB layouts I've ever seen.
On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote:

> Here's a simple one
>
> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
>
>
>
>
>
> ~
> *mcve...@gmail.com*
>
>
> On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:
>
>> Will do, Hopefully parts will be here by Friday.  I may try and shotgun 
>> D35-38 and C52-53 before then as I should have spares around here.
>>
>> Finger's crossed!
>>
>> - Gary
>>
>> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>>
>>> Hi Gary,
>>>
>>> That's a bit odd. While I'm no EE I would have expected that removing 
>>> U17 would have blanked the display if the rest of the circuit was working 
>>> correctly. It looks Q13 should be conducting without U17 fitted and the 
>>> grid should become more negative with respect to the cathode to ensure 
>>> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>>>
>>> - Tristan
>>>
>>> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>>>
 Tristan -

 Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
 swapped Q13 without any change.  I also socketed U17 (6N137) while waiting 
 for a replacement to arrive.  Removing U17 from the circuit leaves the 
 display unchanged, so it does appear that the blanking circuit is the 
 culprit.

 I'll swap U17 once it arrives - and if that doesn't fix things start 
 shotgunning the passives.  

 Thanks again for the guidance, very appreciated!

 - Gary  

 On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:

> Also the voltage between the cathode and the blanking section should 
> be checked (I.e. the voltage across C51) and R65 and R67 should be 
> checked 
> (or potentially replaced along with C51 if shotgunning it). The rest of 
> the 
> high voltage supply appears to be working.
>
> - Tristan
> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>
>> I agree. The blanking is not working and as a result the beam is also 
>> faintly visible as it moves quickly between the characters as well 
>> drawing 
>> the arcs. It would be a good idea to check the BLNK signal on a scope 
>> and 
>> at least see that is is toggling but my money would be on the analogue 
>> blanking section. Given the other side of the optoisolator in the 
>> blanking 
>> section is at a fairly high negative voltage potential (as this reduces 
>> the 
>> need for the deflection amps to handle higher voltages) you will need to 
>> be 
>> careful when probing around there but I would start by checking the 
>> voltages across C54 and C55 (as long as you are confident doing so 
>> safely 
>> with the HV potential to ground). The correct voltages aren't specified 
>> on 
>> the schematic but they will be based on the grid cutoff voltage of the 
>> tube. If you wanted to avoid probing while the clock is on I'd be 
>> inclined 
>> to shotgun replace that section starting with the power supply diodes, 
>> caps 
>> and Q13 and then U17 and finally the passives and see how you go.
>>
>> - Tristan
>> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
>>
>>> From what I remember:
>>> the characters are generated from circles, ellipses or lines which 
>>> in turn are created using sun or cosine waveforms
>>> To make a character the beam is blanked for certain parts eg C is a 
>>> circle with a bit cut out. 
>>>
>>> Looks like the blanking is not working as you’ve got a lot of 
>>> circles and ellipses there. 
>>>
>>> Looks cool though
>>>
>>> Cheers
>>> Ian V
>>>
>>> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
>>>
>>> 
>>>
>>>
>>> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
>>>
>>> I've now got a stable, but scrambled display (see pic's).  I think I 
>>> have a problem with the shape generators but would appreciate any help 
>>> or 
>>> suggestions you could offer.
>>>
>>>
>>> Nah, that's just Cyrillic Neu Sans.
>>>
>>>
>>> Terry Bowman, KA4HJH
>>> "The Mac Doctor"
>>>
>>> "If only you could see what I've seen with your eyes."—Roy Batty, 
>>> *Blade 
>>> Runner*
>>>
>>> -- 
>>> You received this message because you are subscribed to the Google 
>>> Groups "neonixie-l" group.
>>>
>>> To unsubscribe from this group and stop receiving emails from it, 
>>> send an email to neonixie-l+...@googlegroups.com.
>>> To view this discussion on the web, visit 
>>> https://groups.google.com/d/msgid/neonixie-l/3FBEDB26-E97C-44E2-B088-BDA7DAE4A020%40gmail.com
>>>  
>>> 

Re: [neonixie-l] Scope Clock SC200C

[martin martin]

Here's a simple one
https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/





~
*mcvei...@gmail.com *


On Wed, Oct 20, 2021 at 4:16 AM GEK  wrote:

> Will do, Hopefully parts will be here by Friday.  I may try and shotgun
> D35-38 and C52-53 before then as I should have spares around here.
>
> Finger's crossed!
>
> - Gary
>
> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:
>
>> Hi Gary,
>>
>> That's a bit odd. While I'm no EE I would have expected that removing U17
>> would have blanked the display if the rest of the circuit was working
>> correctly. It looks Q13 should be conducting without U17 fitted and the
>> grid should become more negative with respect to the cathode to ensure
>> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>>
>> - Tristan
>>
>> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>>
>>> Tristan -
>>>
>>> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I
>>> swapped Q13 without any change.  I also socketed U17 (6N137) while waiting
>>> for a replacement to arrive.  Removing U17 from the circuit leaves the
>>> display unchanged, so it does appear that the blanking circuit is the
>>> culprit.
>>>
>>> I'll swap U17 once it arrives - and if that doesn't fix things start
>>> shotgunning the passives.
>>>
>>> Thanks again for the guidance, very appreciated!
>>>
>>> - Gary
>>>
>>> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>>>
 Also the voltage between the cathode and the blanking section should be
 checked (I.e. the voltage across C51) and R65 and R67 should be checked (or
 potentially replaced along with C51 if shotgunning it). The rest of the
 high voltage supply appears to be working.

 - Tristan
 On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:

> I agree. The blanking is not working and as a result the beam is also
> faintly visible as it moves quickly between the characters as well drawing
> the arcs. It would be a good idea to check the BLNK signal on a scope and
> at least see that is is toggling but my money would be on the analogue
> blanking section. Given the other side of the optoisolator in the blanking
> section is at a fairly high negative voltage potential (as this reduces 
> the
> need for the deflection amps to handle higher voltages) you will need to 
> be
> careful when probing around there but I would start by checking the
> voltages across C54 and C55 (as long as you are confident doing so safely
> with the HV potential to ground). The correct voltages aren't specified on
> the schematic but they will be based on the grid cutoff voltage of the
> tube. If you wanted to avoid probing while the clock is on I'd be inclined
> to shotgun replace that section starting with the power supply diodes, 
> caps
> and Q13 and then U17 and finally the passives and see how you go.
>
> - Tristan
> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
>
>> From what I remember:
>> the characters are generated from circles, ellipses or lines which in
>> turn are created using sun or cosine waveforms
>> To make a character the beam is blanked for certain parts eg C is a
>> circle with a bit cut out.
>>
>> Looks like the blanking is not working as you’ve got a lot of circles
>> and ellipses there.
>>
>> Looks cool though
>>
>> Cheers
>> Ian V
>>
>> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
>>
>> 
>>
>>
>> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
>>
>> I've now got a stable, but scrambled display (see pic's).  I think I
>> have a problem with the shape generators but would appreciate any help or
>> suggestions you could offer.
>>
>>
>> Nah, that's just Cyrillic Neu Sans.
>>
>>
>> Terry Bowman, KA4HJH
>> "The Mac Doctor"
>>
>> "If only you could see what I've seen with your eyes."—Roy Batty, *Blade
>> Runner*
>>
>> --
>> You received this message because you are subscribed to the Google
>> Groups "neonixie-l" group.
>>
>> To unsubscribe from this group and stop receiving emails from it,
>> send an email to neonixie-l+...@googlegroups.com.
>> To view this discussion on the web, visit
>> https://groups.google.com/d/msgid/neonixie-l/3FBEDB26-E97C-44E2-B088-BDA7DAE4A020%40gmail.com
>> 
>> .
>>
>> --
> You received this message because you are subscribed to the Google Groups
> "neonixie-l" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to neonixie-l+unsubscr...@googlegroups.com.
> To view this discussion on the web, visit
> 

Re: [neonixie-l] Scope Clock SC200C

[GEK]

Will do, Hopefully parts will be here by Friday.  I may try and shotgun 
D35-38 and C52-53 before then as I should have spares around here.

Finger's crossed!

- Gary

On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote:

> Hi Gary,
>
> That's a bit odd. While I'm no EE I would have expected that removing U17 
> would have blanked the display if the rest of the circuit was working 
> correctly. It looks Q13 should be conducting without U17 fitted and the 
> grid should become more negative with respect to the cathode to ensure 
> cutoff. I think you may need to look at the D35-38 and C52 & C53.
>
> - Tristan
>
> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:
>
>> Tristan -
>>
>> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I 
>> swapped Q13 without any change.  I also socketed U17 (6N137) while waiting 
>> for a replacement to arrive.  Removing U17 from the circuit leaves the 
>> display unchanged, so it does appear that the blanking circuit is the 
>> culprit.
>>
>> I'll swap U17 once it arrives - and if that doesn't fix things start 
>> shotgunning the passives.  
>>
>> Thanks again for the guidance, very appreciated!
>>
>> - Gary  
>>
>> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>>
>>> Also the voltage between the cathode and the blanking section should be 
>>> checked (I.e. the voltage across C51) and R65 and R67 should be checked (or 
>>> potentially replaced along with C51 if shotgunning it). The rest of the 
>>> high voltage supply appears to be working.
>>>
>>> - Tristan
>>> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>>>
 I agree. The blanking is not working and as a result the beam is also 
 faintly visible as it moves quickly between the characters as well drawing 
 the arcs. It would be a good idea to check the BLNK signal on a scope and 
 at least see that is is toggling but my money would be on the analogue 
 blanking section. Given the other side of the optoisolator in the blanking 
 section is at a fairly high negative voltage potential (as this reduces 
 the 
 need for the deflection amps to handle higher voltages) you will need to 
 be 
 careful when probing around there but I would start by checking the 
 voltages across C54 and C55 (as long as you are confident doing so safely 
 with the HV potential to ground). The correct voltages aren't specified on 
 the schematic but they will be based on the grid cutoff voltage of the 
 tube. If you wanted to avoid probing while the clock is on I'd be inclined 
 to shotgun replace that section starting with the power supply diodes, 
 caps 
 and Q13 and then U17 and finally the passives and see how you go.

 - Tristan
 On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:

> From what I remember:
> the characters are generated from circles, ellipses or lines which in 
> turn are created using sun or cosine waveforms
> To make a character the beam is blanked for certain parts eg C is a 
> circle with a bit cut out. 
>
> Looks like the blanking is not working as you’ve got a lot of circles 
> and ellipses there. 
>
> Looks cool though
>
> Cheers
> Ian V
>
> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
>
> 
>
>
> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
>
> I've now got a stable, but scrambled display (see pic's).  I think I 
> have a problem with the shape generators but would appreciate any help or 
> suggestions you could offer.
>
>
> Nah, that's just Cyrillic Neu Sans.
>
>
> Terry Bowman, KA4HJH
> "The Mac Doctor"
>
> "If only you could see what I've seen with your eyes."—Roy Batty, *Blade 
> Runner*
>
> -- 
> You received this message because you are subscribed to the Google 
> Groups "neonixie-l" group.
>
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> an email to neonixie-l+...@googlegroups.com.
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> https://groups.google.com/d/msgid/neonixie-l/3FBEDB26-E97C-44E2-B088-BDA7DAE4A020%40gmail.com
>  
> 
> .
>
>

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Re: [neonixie-l] Scope Clock SC200C

[Tristan]

Hi Gary,

That's a bit odd. While I'm no EE I would have expected that removing U17 
would have blanked the display if the rest of the circuit was working 
correctly. It looks Q13 should be conducting without U17 fitted and the 
grid should become more negative with respect to the cathode to ensure 
cutoff. I think you may need to look at the D35-38 and C52 & C53.

- Tristan

On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote:

> Tristan -
>
> Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I swapped 
> Q13 without any change.  I also socketed U17 (6N137) while waiting for a 
> replacement to arrive.  Removing U17 from the circuit leaves the display 
> unchanged, so it does appear that the blanking circuit is the culprit.
>
> I'll swap U17 once it arrives - and if that doesn't fix things start 
> shotgunning the passives.  
>
> Thanks again for the guidance, very appreciated!
>
> - Gary  
>
> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:
>
>> Also the voltage between the cathode and the blanking section should be 
>> checked (I.e. the voltage across C51) and R65 and R67 should be checked (or 
>> potentially replaced along with C51 if shotgunning it). The rest of the 
>> high voltage supply appears to be working.
>>
>> - Tristan
>> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>>
>>> I agree. The blanking is not working and as a result the beam is also 
>>> faintly visible as it moves quickly between the characters as well drawing 
>>> the arcs. It would be a good idea to check the BLNK signal on a scope and 
>>> at least see that is is toggling but my money would be on the analogue 
>>> blanking section. Given the other side of the optoisolator in the blanking 
>>> section is at a fairly high negative voltage potential (as this reduces the 
>>> need for the deflection amps to handle higher voltages) you will need to be 
>>> careful when probing around there but I would start by checking the 
>>> voltages across C54 and C55 (as long as you are confident doing so safely 
>>> with the HV potential to ground). The correct voltages aren't specified on 
>>> the schematic but they will be based on the grid cutoff voltage of the 
>>> tube. If you wanted to avoid probing while the clock is on I'd be inclined 
>>> to shotgun replace that section starting with the power supply diodes, caps 
>>> and Q13 and then U17 and finally the passives and see how you go.
>>>
>>> - Tristan
>>> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
>>>
 From what I remember:
 the characters are generated from circles, ellipses or lines which in 
 turn are created using sun or cosine waveforms
 To make a character the beam is blanked for certain parts eg C is a 
 circle with a bit cut out. 

 Looks like the blanking is not working as you’ve got a lot of circles 
 and ellipses there. 

 Looks cool though

 Cheers
 Ian V

 On 19 Oct 2021, at 06:08, Mac Doktor  wrote:

 


 On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:

 I've now got a stable, but scrambled display (see pic's).  I think I 
 have a problem with the shape generators but would appreciate any help or 
 suggestions you could offer.


 Nah, that's just Cyrillic Neu Sans.


 Terry Bowman, KA4HJH
 "The Mac Doctor"

 "If only you could see what I've seen with your eyes."—Roy Batty, *Blade 
 Runner*

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Re: [neonixie-l] Scope Clock SC200C

[GEK]

Tristan -

Thanks for those hints.  the BLNK signal is pulsing at 60hz, and I swapped 
Q13 without any change.  I also socketed U17 (6N137) while waiting for a 
replacement to arrive.  Removing U17 from the circuit leaves the display 
unchanged, so it does appear that the blanking circuit is the culprit.

I'll swap U17 once it arrives - and if that doesn't fix things start 
shotgunning the passives.  

Thanks again for the guidance, very appreciated!

- Gary  

On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote:

> Also the voltage between the cathode and the blanking section should be 
> checked (I.e. the voltage across C51) and R65 and R67 should be checked (or 
> potentially replaced along with C51 if shotgunning it). The rest of the 
> high voltage supply appears to be working.
>
> - Tristan
> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:
>
>> I agree. The blanking is not working and as a result the beam is also 
>> faintly visible as it moves quickly between the characters as well drawing 
>> the arcs. It would be a good idea to check the BLNK signal on a scope and 
>> at least see that is is toggling but my money would be on the analogue 
>> blanking section. Given the other side of the optoisolator in the blanking 
>> section is at a fairly high negative voltage potential (as this reduces the 
>> need for the deflection amps to handle higher voltages) you will need to be 
>> careful when probing around there but I would start by checking the 
>> voltages across C54 and C55 (as long as you are confident doing so safely 
>> with the HV potential to ground). The correct voltages aren't specified on 
>> the schematic but they will be based on the grid cutoff voltage of the 
>> tube. If you wanted to avoid probing while the clock is on I'd be inclined 
>> to shotgun replace that section starting with the power supply diodes, caps 
>> and Q13 and then U17 and finally the passives and see how you go.
>>
>> - Tristan
>> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
>>
>>> From what I remember:
>>> the characters are generated from circles, ellipses or lines which in 
>>> turn are created using sun or cosine waveforms
>>> To make a character the beam is blanked for certain parts eg C is a 
>>> circle with a bit cut out. 
>>>
>>> Looks like the blanking is not working as you’ve got a lot of circles 
>>> and ellipses there. 
>>>
>>> Looks cool though
>>>
>>> Cheers
>>> Ian V
>>>
>>> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
>>>
>>> 
>>>
>>>
>>> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
>>>
>>> I've now got a stable, but scrambled display (see pic's).  I think I 
>>> have a problem with the shape generators but would appreciate any help or 
>>> suggestions you could offer.
>>>
>>>
>>> Nah, that's just Cyrillic Neu Sans.
>>>
>>>
>>> Terry Bowman, KA4HJH
>>> "The Mac Doctor"
>>>
>>> "If only you could see what I've seen with your eyes."—Roy Batty, *Blade 
>>> Runner*
>>>
>>> -- 
>>> You received this message because you are subscribed to the Google 
>>> Groups "neonixie-l" group.
>>>
>>> To unsubscribe from this group and stop receiving emails from it, send 
>>> an email to neonixie-l+...@googlegroups.com.
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>>> https://groups.google.com/d/msgid/neonixie-l/3FBEDB26-E97C-44E2-B088-BDA7DAE4A020%40gmail.com
>>>  
>>> 
>>> .
>>>
>>>

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Re: [neonixie-l] Scope Clock SC200C

[Tristan]

Also the voltage between the cathode and the blanking section should be 
checked (I.e. the voltage across C51) and R65 and R67 should be checked (or 
potentially replaced along with C51 if shotgunning it). The rest of the 
high voltage supply appears to be working.

- Tristan
On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote:

> I agree. The blanking is not working and as a result the beam is also 
> faintly visible as it moves quickly between the characters as well drawing 
> the arcs. It would be a good idea to check the BLNK signal on a scope and 
> at least see that is is toggling but my money would be on the analogue 
> blanking section. Given the other side of the optoisolator in the blanking 
> section is at a fairly high negative voltage potential (as this reduces the 
> need for the deflection amps to handle higher voltages) you will need to be 
> careful when probing around there but I would start by checking the 
> voltages across C54 and C55 (as long as you are confident doing so safely 
> with the HV potential to ground). The correct voltages aren't specified on 
> the schematic but they will be based on the grid cutoff voltage of the 
> tube. If you wanted to avoid probing while the clock is on I'd be inclined 
> to shotgun replace that section starting with the power supply diodes, caps 
> and Q13 and then U17 and finally the passives and see how you go.
>
> - Tristan
> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:
>
>> From what I remember:
>> the characters are generated from circles, ellipses or lines which in 
>> turn are created using sun or cosine waveforms
>> To make a character the beam is blanked for certain parts eg C is a 
>> circle with a bit cut out. 
>>
>> Looks like the blanking is not working as you’ve got a lot of circles and 
>> ellipses there. 
>>
>> Looks cool though
>>
>> Cheers
>> Ian V
>>
>> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
>>
>> 
>>
>>
>> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
>>
>> I've now got a stable, but scrambled display (see pic's).  I think I have 
>> a problem with the shape generators but would appreciate any help or 
>> suggestions you could offer.
>>
>>
>> Nah, that's just Cyrillic Neu Sans.
>>
>>
>> Terry Bowman, KA4HJH
>> "The Mac Doctor"
>>
>> "If only you could see what I've seen with your eyes."—Roy Batty, *Blade 
>> Runner*
>>
>> -- 
>> You received this message because you are subscribed to the Google Groups 
>> "neonixie-l" group.
>>
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to neonixie-l+...@googlegroups.com.
>> To view this discussion on the web, visit 
>> https://groups.google.com/d/msgid/neonixie-l/3FBEDB26-E97C-44E2-B088-BDA7DAE4A020%40gmail.com
>>  
>> 
>> .
>>
>>

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Re: [neonixie-l] Scope Clock SC200C

[Tristan]

I agree. The blanking is not working and as a result the beam is also 
faintly visible as it moves quickly between the characters as well drawing 
the arcs. It would be a good idea to check the BLNK signal on a scope and 
at least see that is is toggling but my money would be on the analogue 
blanking section. Given the other side of the optoisolator in the blanking 
section is at a fairly high negative voltage potential (as this reduces the 
need for the deflection amps to handle higher voltages) you will need to be 
careful when probing around there but I would start by checking the 
voltages across C54 and C55 (as long as you are confident doing so safely 
with the HV potential to ground). The correct voltages aren't specified on 
the schematic but they will be based on the grid cutoff voltage of the 
tube. If you wanted to avoid probing while the clock is on I'd be inclined 
to shotgun replace that section starting with the power supply diodes, caps 
and Q13 and then U17 and finally the passives and see how you go.

- Tristan
On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote:

> From what I remember:
> the characters are generated from circles, ellipses or lines which in turn 
> are created using sun or cosine waveforms
> To make a character the beam is blanked for certain parts eg C is a circle 
> with a bit cut out. 
>
> Looks like the blanking is not working as you’ve got a lot of circles and 
> ellipses there. 
>
> Looks cool though
>
> Cheers
> Ian V
>
> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
>
> 
>
>
> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
>
> I've now got a stable, but scrambled display (see pic's).  I think I have 
> a problem with the shape generators but would appreciate any help or 
> suggestions you could offer.
>
>
> Nah, that's just Cyrillic Neu Sans.
>
>
> Terry Bowman, KA4HJH
> "The Mac Doctor"
>
> "If only you could see what I've seen with your eyes."—Roy Batty, *Blade 
> Runner*
>
> -- 
> You received this message because you are subscribed to the Google Groups 
> "neonixie-l" group.
>
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to neonixie-l+...@googlegroups.com.
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> https://groups.google.com/d/msgid/neonixie-l/3FBEDB26-E97C-44E2-B088-BDA7DAE4A020%40gmail.com
>  
> 
> .
>
>

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Re: [neonixie-l] Scope Clock SC200C

['Ian Vine' via neonixie-l]

>From what I remember:
the characters are generated from circles, ellipses or lines which in turn are 
created using sun or cosine waveforms
To make a character the beam is blanked for certain parts eg C is a circle with 
a bit cut out. 

Looks like the blanking is not working as you’ve got a lot of circles and 
ellipses there. 

Looks cool though

Cheers
Ian V

> On 19 Oct 2021, at 06:08, Mac Doktor  wrote:
> 
> 
>> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
>> 
>> I've now got a stable, but scrambled display (see pic's).  I think I have a 
>> problem with the shape generators but would appreciate any help or 
>> suggestions you could offer.
> 
> Nah, that's just Cyrillic Neu Sans.
> 
> 
> Terry Bowman, KA4HJH
> "The Mac Doctor"
> 
> "If only you could see what I've seen with your eyes."—Roy Batty, Blade Runner
> 
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Re: [neonixie-l] Scope Clock SC200C

[Mac Doktor]

> On Oct 18, 2021, at 7:53 PM, Gary Kaufman  wrote:
> 
> I've now got a stable, but scrambled display (see pic's).  I think I have a 
> problem with the shape generators but would appreciate any help or 
> suggestions you could offer.

Nah, that's just Cyrillic Neu Sans.


Terry Bowman, KA4HJH
"The Mac Doctor"

"If only you could see what I've seen with your eyes."—Roy Batty, Blade Runner

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Re: [neonixie-l] Scope Clock SC200C

[Gary Kaufman]

The documentation is online at http://www.cathodecorner.com/sc200c.html

It is a somewhat amusing problem :)

I should say that it was working fine for several years prior to this 
problem.


- Gary

On 10/18/2021 9:07 PM, Toby Thain wrote:

On 2021-10-18 7:53 p.m., Gary Kaufman wrote:
I've been unsuccessful in reaching David Forbes, so thought I would 
ask the group for help.


My SC200C has been "unhealthy" for a while now, and I'm trying to get 
it running properly.


I've now got a stable, but scrambled display (see pic's).  I think I 
have a problem with the shape generators but would appreciate any 
help or suggestions you could offer.




I know this isn't helpful at all, but I have to admit I find this 
accidental font quite charming.


Graphics bugs are the best bugs.

Are there schematics, source code etc we can access?

--T


I've swapped the 74HCxx parts with no improvement.

Many thanks in advance!

- Gary


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Re: [neonixie-l] Scope Clock SC200C

[Toby Thain]

On 2021-10-18 7:53 p.m., Gary Kaufman wrote:
I've been unsuccessful in reaching David Forbes, so thought I would ask 
the group for help.


My SC200C has been "unhealthy" for a while now, and I'm trying to get it 
running properly.


I've now got a stable, but scrambled display (see pic's).  I think I 
have a problem with the shape generators but would appreciate any help 
or suggestions you could offer.




I know this isn't helpful at all, but I have to admit I find this 
accidental font quite charming.


Graphics bugs are the best bugs.

Are there schematics, source code etc we can access?

--T


I've swapped the 74HCxx parts with no improvement.

Many thanks in advance!

- Gary


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[neonixie-l] Scope Clock SC200C

[Gary Kaufman]

I've been unsuccessful in reaching David Forbes, so thought I would ask 
the group for help.


My SC200C has been "unhealthy" for a while now, and I'm trying to get it 
running properly.


I've now got a stable, but scrambled display (see pic's).  I think I 
have a problem with the shape generators but would appreciate any help 
or suggestions you could offer.


I've swapped the 74HCxx parts with no improvement.

Many thanks in advance!

- Gary


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