Re: [volt-nuts] Cropico DO4A Digital Ohmmeter

[Didier Juges]

Or expose enough leads of the damaged parts to check what it is and find a
replacement.

If it's on the heatsink, it is probably used as a linear regulator and
there will be a large section of the datasheet that you can safely ignore.

On Sun, Apr 29, 2018, 7:02 AM Nigel Clarke via volt-nuts 
wrote:

> Perhaps somewhat off topic but just wondering if anybody here would have a
> service manual for this instrument, or even just a schematic particularly
> of the power supply section?
>
> I've just bought one that was totally dead on arrival and it looks to have
> been blessed by the idiot's touch, both from an original mechanical design
> point of view and subsequent user intervention.
>
> It turns out the the TO220 PSU power transistor is mounted on the back
> panel and rigidly soldered to the circuit board, although I still haven't
> figured out quite how they managed that in this instance, and there's
> nothing to prevent removal of the back panel, even with the covers still
> attached, which someone has obviously done and snapped off all three
> transistor legs flush with the body.
>
> There's no obvious PCB damage, so it could have been a lot worse, and I
> should be able to add some flexible tails to the PCB and then solder these
> to the replacement transistor pins to include some future stress relief,
> but this LM723 based PSU looks to be quite complex, it includes a lead acid
> battery charger with overvoltage and deep discharge protection, thermal
> protection too by the looks of it, and all involving another five ICs plus
> associated circuitry, so some adjustment is likely to be necessary, which
> is where the manufacture's instructions would be most useful.
>
> I guess plan B might be to expose enough of the leads on the existing
> transistor to reuse that if possible, whilst hoping the original adjustment
> still holds, but aside from the quite "interesting" surgery required it
> would still be nice to check the adjustments anyway.
>
> Nigel, GM8PZR
>
>
>
>
>
>
>
>
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Re: [volt-nuts] *WAY* too expensive for even Keysight to redesign

[Didier Juges]

Our life cycle management program assures you of a dependable, quality
source of obsolete IC's forever. 
No mention that the price may go up exponentially each time you ask for a
quote, and don't try to buy two dozens. They probably won't make a run for
 much less than several thousand pieces, and there will be steep lot
charges in addition to a very high unit price.
Been there, done that...

Didier KO4BB


On Wed, May 13, 2015 at 11:55 AM, Daniel Mendes dmend...@gmail.com wrote:


 From the site you linked: Our life cycle management program assures you
 of a dependable, quality source of obsolete IC's forever. 

 Now it was my turn of having a good laugh.. thanks for that, I didn´t knew
 that this service existed.

 Daniel


 On 13/05/2015 13:37, Marv @ Home wrote:

 Aside, there are private fabrication houses that make short runs of
 obsolete chips in order to keep mission critical electronics running, such
 as in aerospace and military applications.  I'm not sure what Keysight
 would actually do, but I would presume not only do they stockpile key
 parts, both active and passives, as well as full boards for board level
 swaps, but periodic re-checking their inventory for functional integrity
 can be a never ending task as components age beyond their expected
 operational life.  If parts truly were to become obsolete even beyond
 private fabrication, their management should design replacements boards and
 field test them way in advance of parts becoming extinct, until they
 decided the product was not worth maintaining.

 http://www.lansdale.com/


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Re: [volt-nuts] VFD wearout (was dark display for 3458)

[Didier Juges]

Hi Chuck,

It is very interesting and unexpected. These displays were replaced for no 
other reason than they were difficult to read, and now this particular sample 
is just fine.

I have a couple more, I will try to cycle them through my prototype.

I know that I have had a number of clocks with VFDs that became unusable for 
the same reason over the years. This is the first time that I get one to 
restore itself.

Not sure how much of that would be useful with the 3548 display.

Didier KO4BB


On April 28, 2015 11:05:19 AM CDT, Chuck Harris cfhar...@erols.com wrote:
Hi Didier,

That is most interesting!

The architecture of the displays is such that there are multiple
cathode wires, one over the top of each row of segments, usually.
The cathodes are run dark, so they are barely emitting, and cannot
really ever burn out.

I have found the ugly looking displays are the result of the cathodic
emission right under the wire being better than between the wires,
rendering a mottled appearance.

In some of the early clocks and alarm clocks, that used VFD's (since
the US clocks are always in 12 hour display mode) if they were changed
to 24 hour mode, after a long life, the E digits that make up the
most significant digit were always much brighter than the rest of the
digits on the display, rendering a 2 where the newly lit horizontal
segments were brighter than the rest.

In any case, I have some VFD's that have been in continuous use since
I graduated from college, and that was a long, long, time ago.  And
they are still going strong.

I have to wonder about the failures in the 3458 display.  My instinct
tells me that it isn't the VFD but rather the driver/power supply that
has failed.  Probably a bad electrolytic capacitor if things go the
way they usually do.

-Chuck Harris

Didier Juges wrote:
 After the thread about the 3458 display, I went back to one of those
VFD
 that I mentioned in my earlier post. These had been used with only a
few
 digits turned on on the first line, the rest of the display being
normally
 turned off and only used occasionally. After several years of
continuous
 operation, the digits that were used  had lost brightness and more
 interestingly, the other digits had also lost brightness but also
looked
 botched (the brightness was very uneven).

 It turns out I have been using one of these old displays on a new
project
 (it's a development job, so the unevenness does not bother me at the
moment
 since this display will not ship). After about 2 weeks of continuous
use
 where most of the digits are used, the display is now just about back
to
 normal. somewhat dimmer than a new one, but the unevenness has
completely
 disappeared.

 It looks like either the digits themselves, or the cathode wire, had
become
 contaminated as a result of not being used, and a few days of
operation
 restored their activity.

 Even more interesting, at the moment, I cannot detect a difference in
 brightness between the old digits that were on for several years and
those
 that were not. The display is generally dimmer than a new one, but
the new
 ones are a different part number, the original device having been
 discontinued, so it may also be that the new display is brighter
because of
 process improvements by the manufacturer (something the manufacturer
 advertised when they introduced the new device).

 On this development job, most of the digits are used, and the display
is
 constantly changing (scrolling messages).

 Anyhow, I thought it would be interesting to mention.

 Didier KO4BB
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[volt-nuts] VFD wearout (was dark display for 3458)

[Didier Juges]

After the thread about the 3458 display, I went back to one of those VFD
that I mentioned in my earlier post. These had been used with only a few
digits turned on on the first line, the rest of the display being normally
turned off and only used occasionally. After several years of continuous
operation, the digits that were used  had lost brightness and more
interestingly, the other digits had also lost brightness but also looked
botched (the brightness was very uneven).

It turns out I have been using one of these old displays on a new project
(it's a development job, so the unevenness does not bother me at the moment
since this display will not ship). After about 2 weeks of continuous use
where most of the digits are used, the display is now just about back to
normal. somewhat dimmer than a new one, but the unevenness has completely
disappeared.

It looks like either the digits themselves, or the cathode wire, had become
contaminated as a result of not being used, and a few days of operation
restored their activity.

Even more interesting, at the moment, I cannot detect a difference in
brightness between the old digits that were on for several years and those
that were not. The display is generally dimmer than a new one, but the new
ones are a different part number, the original device having been
discontinued, so it may also be that the new display is brighter because of
process improvements by the manufacturer (something the manufacturer
advertised when they introduced the new device).

On this development job, most of the digits are used, and the display is
constantly changing (scrolling messages).

Anyhow, I thought it would be interesting to mention.

Didier KO4BB
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Re: [volt-nuts] dark display for 3458

[Didier Juges]

I have fielded two dozen pieces of equipment with 2x16 VFD from Noritake. These 
are on 24/7 and they were shipped over a 4 year period starting in 2000. In 
normal state, there are 4 digits always turned on on the first line. The other 
digits are rarely turned on.
The displays start being noticeably darker after 2 years and barely usable 
after 3-4 years. The digits that are not normally used seem to last much longer 
but they eventually get darker, just at a much slower rate. It may be due to 
contamination rather than the filament itself wearing out. By now, most have 
been replaced at least once, with a different part number because the old one 
has become obsolete.

Didier KO4BB


On April 11, 2015 11:37:49 AM CDT, Chuck Harris cfhar...@erols.com wrote:
 From visual inspection, the filaments in these
vacuu-fluroescent displays look like bare wire,
which would make them some sort of doped tungsten
alloy.. which doesn't really ever wear out.

The only problems I have ever seen is due to
phosphor fatigue.  The display stops glowing
on whichever digit is on all the time... and
you see this as unequal brightness between the
digits.

I have never seen a vacuum fluorescent display
just fade away in any reasonable time.  They
seem to go for years and years.  I have alarm
clocks and ovens, and microwaves with these
displays some of which have been glowing for
around 40 years now, and still going strong.

I have seen vacuu-fluorescent displays that
have gone dark, and found that the reason is
the filament supply has quit...usually due to
a bad electrolytic capacitor.

-Chuck Harris

Don@True-Cal wrote:
 The 3458A DISP? command, rather entered from the front panel or via a
GPIB Command is not adequately discussed in the User's Manual IMO.
There are four numeric values 0,1,2  3 plus the ability to enter a
string value as mentioned below. All four values are supported via the
GPIB, but only 0,1 2 are valid modes for the front panel DISP? command
- the front panel DISP? 3 seems to be accepted and interpreted the same
as DISP? 1 (On). The value 0 (Off) seems somewhat pointless and simply
places dashes across the display. The value 1 (On) is the default and
normal mode. The value 2 (Msg) displays control messages only. These
three modes would obviously offer no help to prolonging display life
since the display filament would need to remain on. The interesting
DISP? 3 (Clr) is the one in question rather is removes power to the
display filament providing some help for display life. I'm not sure
without actually getting inside and testing if filament voltage is
present or not. Checking t
 h
e
schematics for a display filament voltage interrupter might also
be a clue, but would still be firmware dependent. I use Agilent VEE for
3458A control and plotting and have provided a dynamic display control
using DISP? 0-3 modes and I often leave the display in mode 3 (Clr) for
long plot cycles (sometimes weeks). In this mode, the display is
completely blank, including no enunciator (sampling) indicators at all.
My hope is that the display filaments are off. Anyone know for sure?

 Don

 -Original Message-
 From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of new
 Sent: Saturday, April 11, 2015 12:09 AM
 To: volt-nuts@febo.com
 Subject: [volt-nuts] dark display for 3458

 Hi, again...

Now that I have the keysight connection expert running my two sick
3458s, I don't need to look at data on the displays. To keep them from
burning out, I wanted to turn them off.

 I found a workaround of:

 DISP 0,'  (16 spaces) .'

 This put a period on the bottom of the blank screen and moves it 16
spaces to the right.
 right off the screen!

 So now the display is dark and only shows things like the 'err'
message.

 QUESTION - will this kill the 3458 or its display somehow?

 Willy
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Re: [volt-nuts] Design Spark PCB Design Package

[Didier Juges]

I am there too. I have used ExpressPCB because it is actually very fast and
easy for small projects.
I also use the schematic capture for illustrations (when I just need a
schematic, no PWB) because it also makes decent looking schematics without
fuss. Creating component models bot both schematic and layout is quick and
easy.
It is decidedly not for professional uses, but for small projects, it is
hard to beat.

I have installed KiCad (a month ago) and got extremely frustrated trying to
create models for schematic components. Whatever I did I could not find a
way to get the component in a library and I eventually lost the work.
Instructions/tutorials are sorely missing. Then I found out it had problems
dealing with mixed metric and imperial units, so I abandoned it. Aside from
prototypes which I do with ExpressPCB,

For the last 10 years, I have been having my (good) boards done by a
professional PWB designer who is using a $15,000 package. It costs more,
but it is done quickly, 100% error free and there are 0 issues in
manufacturing :)

Didier


On Tue, Jan 6, 2015 at 11:11 AM, BIll Ezell w...@quackers.net wrote:


 On 1/6/2015 12:00 PM, volt-nuts-requ...@febo.com wrote:

 Re: Design Spark PCB Design Package

  It depends on what you need PCBs for. I've used ExpressPCB for years.
 They have proprietary layout software, all very manual, no routing, and
 free. It will also do multilayer, vias, fills, etc. The reason I use them
 is that you can get 3 3x5 boards from them for $60 if you use their app.
 They also have a schematic capture app that works with the layout app and
 does some basic netlist checking. I find them very convenient for one-off
 projects that will fit.

 --
 Bill Ezell
 --
 The day Microsoft makes something that doesn't suck
 will be the day they make vacuum cleaners.


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Re: [volt-nuts] Fluke 732A Questions

[Didier Juges]

I may be unable to move manuals until the end of the week. However, you can 
always download a manual that was just uploaded by using ftp. Check the Upload 
button on the Manuals page.

Happy New Year everyone.

Didier KO4BB


R.Phillips phill...@btinternet.com wrote:
Hi Todd
I would appreciate a copy of your later issue manual for the 732A -
please 
let me know when you make this available  -  Dider's site ?
Many thanks
Roy


-Original Message- 
From: T. Micallef
Sent: Monday, December 30, 2013 4:03 AM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] Fluke 732A Questions

Joe,

I don't know if it makes any difference but my manual is for the
732A/AN p/n
788414

I found a couple of brochures that I scanned and uploaded too.

I forgot to mention, I have been collecting information regarding the
techniques used to do intercomparisons using scanners like the Data
Proof
models. While searching a couple of weeks ago, I came across an old
document
from a Measurement Science Conference back in 1983. The document
contains an
article regarding the testing of the Fluke 735C. I thought you may have
little to no info regarding your reference and thought I would let you
know
about it.

The document is easy to find using google. It is named MSC1983.pdf
I will upload it as well, but I was not sure if Didier wants to track
conference docs.

Todd





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Re: [volt-nuts] VS330

[Didier Juges]

I do not use Acrobat, but the manual opens fine in the Fox it Reader

Didier KO4BB

RF PRECHTL  K7DFW k7...@clatskanie.com wrote:





Downloaded this pdf from KO4BB and my Adobe reader 6.0.6 - 01/08/2007
claims it is damaged and not
capable of opening.


Is this a case where Adobe is not backwards compatible and the KO4BB
Adobe being too new for my
2007
edition?


Rolynn

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Re: [volt-nuts] What really gets calibrated?

[Didier Juges]

The big difference is that nowadays, adjustment is done in software without 
moving parts. There is no wear out involved in doing frequent adjustment and 
through the software you can record by how much each setting was adjusted.

These were the main reasons for not adjusting an instrument that was in spec 
when going to the cal lab.


Didier KO4BB

Orin Eman orin.e...@gmail.com wrote:
On Mon, Jul 29, 2013 at 12:25 AM, David Kirkby
david.kir...@onetel.netwrote:

 On 28 July 2013 23:15, Joseph Gray jg...@zianet.com wrote:
  I recently had it explained to me that calibration is really just
  checking a piece of gear against a known standard, to see if it
meets the
  manufacturers specification. If it is outside specified values,
then it
  gets adjusted, not calibrated.


 I think it depends somewhat on who cals it, and under what conditions
 are stated.

 I think if something is specified with an uncertainty of 10%, and is
 found to be 9.9% off, then I feel it should be adjusted as it is
close
 to the limits of being acceptable, even though it is within spec.

 Certainly with Agilent, you will pay more for the cal if you want
both
 before and after data.



Here is what Agilent say about the new 3446xA DMMS:

Adjustment is Recommended

Whatever calibration interval you select, Agilent Technologies
recommends
that complete re-adjustment should
always be performed at the calibration interval. This ensures that the
instrument will remain within specifications for
the next calibration interval and provides the best long-term
stability.
Performance data measured during performance
verification tests does not mean that the instrument will remain within
these limits unless the adjustments are
performed. Use the calibration count to verify that all adjustments
have
been performed. 

This is however, a closed box calibration where the calibration process
stores correction constants in non-volatile memory.  There are no
concerns
about flaky trimpots etc..

Orin.
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Re: [volt-nuts] Fwd: Old resistors

[Didier Juges]

They can be useful to test power supplies, at least the lower value ones. This 
one looks fairly high value (small wire) so probably useless unless you have a 
museum.

Didier KO4BB

Joseph Gray jg...@zianet.com wrote:
I know someone who has several of these old style resistors. Can anyone
tell me anything about them? Are they of any use?

https://dl.dropboxusercontent.com/u/19599147/Resistor%20-%20side.jpg

https://dl.dropboxusercontent.com/u/19599147/Resistor%20-%20front.jpg

Joe Gray
W5JG
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[volt-nuts] ***SPAM*** Re: Solartron Files

[Didier Juges]

Thank you Mickle!

PS: my wife is from Tomsk, Russia. Beautiful country,  a little cooler than 
Florida :)

Михаил timk...@yandex.ru wrote:

Thank you, Didier!
I uploaded file on the www.ko4bb.com

Regards,
Mickle T.

P.S. Sorry, I mistakenly chose the developer name :(

Saturday, May 11, 2013, 4:48:14 PM, you wrote:
DJ Mikhail, you are welcome to upload your file(s) to my web site
DJ www.ko4bb.com. Click on the Manuals button and then Upload File
and follow the (simple) instructions
DJ  
DJ Thanks in advance,
DJ Didier KO4BB



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Re: [volt-nuts] Solartron Files

[Didier Juges]

Sam,

I think I saw an email from you saying some Solartron files on my web site
were corrupted. Can't find the email now. I just checked the 7081 service
manual and it opens up fine here.

Can you resend me this email?

Thanks

Didier


On Fri, May 10, 2013 at 7:45 PM, Sam Reaves sam.rea...@gmail.com wrote:

 Hello,

 Does anyone have the two Solartrin 7081 files posted by Mickle?

 The source I found has corrupt files.

 Thank you,

 Sam
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Re: [volt-nuts] Solartron Files

[Didier Juges]

Mikhail, you are welcome to upload your file(s) to my web site www.ko4bb.com.
Click on the Manuals button and then Upload File and follow the
(simple) instructions

Thanks in advance,

Didier KO4BB


On Sat, May 11, 2013 at 1:18 AM, Михаил timk...@yandex.ru wrote:

 Hi, Sam!
 Sorry for the long wait.
 This is all that I have about the Solartron 7081:
 http://www.fileserve.com/file/xHrRCvd/Solartron7081.rar (100 Mb)


 Regards,
 Mickle T.

 Saturday, May 11, 2013, 4:45:57 AM, you wrote:
 SR Hello,
 SR Does anyone have the two Solartrin 7081 files posted by Mickle?
 SR The source I found has corrupt files.
 SR Thank you,

 SR Sam


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