Re: A little power circuit explanation please

[Adrian Graham via cctalk]

> On 23 Aug 2017, at 00:49, Rob Doyle via cctalk  wrote:
> 
> It's a little switching power supply.  It steps up the 9V input voltage to 
> something a few volts greater than 12V to feed the 12V regulator.
> 
> If your 12V is correct, it is probably working.
> 

This is from 2 months ago but I was puzzling over the 12V circuit in this 
particular machine and also maybe suffering from a red herring since the PSU I 
was using is from a ZXSpectrum+2 which is an unregulated 12-14V lump so the 
coil was already being fed 12V.

A 

> Rob.
> 
> On 8/22/2017 4:30 PM, Adrian Graham via cctalk wrote:
>> Hi folks,
>> Failing Atari PSU aside I remembered a question I had ages ago but never 
>> posted about the power circuit of another 80s home micro, the Enterprise 64. 
>> This machine is powered by a 2A 9V unregulated PSU and internally there’s a 
>> pair of 7805s and a 78L12 to smooth things out.
>> There’s also a small transformer coil in there too (L1 on the following 
>> schematic) and I’m not entirely sure what it’s for. Here’s the schematic of 
>> the original circuit, any enlightenment gratefully received since I have an 
>> Enterprise 64 with a dead coil :)
>> http://www.binarydinosaurs.co.uk/ep64PowerRegulators.png 
>> 
>> Cheers!
>> —
>> Adrian/Witchy
>> Binary Dinosaurs - Celebrating Computing History from 1972 onwards
> 

Re: DCC-116 E / DATA GENERAL NOVA 2/10 / Nixdorf 620 - Restoring and restarting

[Dominique Carlier via cctalk]

Here is the situation.

The + 5V 12A that collapses comes out from pins 10-14 / 36-40, the other 
+ 5V 12A (pins 15-22 / 36-40) never goes down.


All that I surrounded in green on that image (1950×2361, zoomable) are 
the components that I tested on the power supply G2, A3 motherboard, 
regulation board and heatsink A1 + A2:

http://www.zeltrax.com/classiccmp_forum/psu_g2_test/g2_tested_components.jpg

To eliminate some doubts and because I do not have some spare parts on 
hand, I switched the modules A1 and A2, same result. Idem with the 
transistors 2N2905, same result.
The result is always the same : it's always the +5V on pins 10-14 / 
36-40 that collapses, never the other output.


Some resistors are not yet tested is because these must be de-soldered 
for a valid test, but the printed circuit is very fragile and many 
component have legs bent into the weld.


Except for the not tested components (among others the LM376, the 
rectifier diodes) At this stage I start again to suspect a little 
everything. The famous large capacitors of the power supply (C1 to C4). 
But also a possible problems on the boards of the computer itself.


As one of you mentioned, the hypothesis of shorted decoupling capacitors 
on the boards could put the power supply in default.


Note that the machine runs normally with the CPU board, three core 
memory boards (400w each) + two multiplexing boards for terminals + the 
printer board.

If I add only one of these remaining board:
- Disk Pack Controller
- 9-track tape Controller
- "scanner" board (also for terminals)

-> Power Fail.

Note that : if I only connect the CPU and the disk pack controller card: 
Power Fail too !!


What makes me doubtful about this scenario is that I can not imagine 
that these three boards, each causing the Power Fail, could fail 
simultaneously. Remember that the first time I powered up the beast (one 
big hour), the machine was working with all the boards and Power Fail 
appeared at once.
I have not retested since but also note that by adding an external power 
supply just for the deficient + 5V , the machine has restarted and even 
booted the operating system.


If you have another ideas? LM376?

Thanks

Dominique


On 20/08/2017 09:08, Brent Hilpert wrote:

On 2017-Aug-19, at 12:10 PM, Dominique Carlier via cctalk wrote:

Maybe it's better to give us all the useful information these power supplies, 
moreover it might be useful to other people with the same computer.

An overall bloc diagram of the D-116 power supply including G1 and G2.
http://www.zeltrax.com/classiccmp_forum/psu_overall_bloc_diagram.jpg

The complete schematics of the part of the power supply named G2.
http://www.zeltrax.com/classiccmp_forum/g2_schematics.jpg

A drawing of the regulation board of the power supply G2 with the physical 
locations of the components.
http://www.zeltrax.com/classiccmp_forum/g2_regulator_board.jpg

The schematics of this regulation board.
http://www.zeltrax.com/classiccmp_forum/g2_regulator_board_schematics.jpg

And a bit of literature concerning the principle of operation about the 
regulation with this PSU (you will understand better why I am a little bit lost 
;-) This principle of regulation with a panoply of verification and Protection 
systems everywhere is unusual for me)
http://www.zeltrax.com/classiccmp_forum/psu_regulation_principe.jpg

I have already tried without the CPU board: same symptoms. Next step, try to 
check the capacitors in operation.



Results of the observations:
- This is definitely the regulated +5V of the G2 power supply. More I add 
boards more the + 5v level goes down. +5v, +4.8v, +3.6v, +2.9v. It remains 
stable however with just the CPU and the three core memory boards, it becomes 
difficult for the power supply when I add boards in addition to these.
- This is definitely not a problem at the level of the Power Fail circuit.
- The big capacitors are not in fault (I rechecked twice).
- So this maybe a problem at the level of the regulation itself, the +5V 
balancing system ?

Question: a faulty voltage regulator can behave in this way? I always thought 
it worked or it did not work, but not between the two states depending on the 
charge.

(In answer to the question, yes, a faulty regulator can produce 'in-between' 
output voltage.)

As is typical for power supplies of this type and era, this power supply 
includes current limiting circuitry.

The current-limiting circuitry will throttle down the output voltage (not shut 
it off completely) as the output current draw goes above a design limit.
This would appear to fit the symptoms you describe.

The current-limiting circuitry works by placing a small-value resistor in the 
current path after the main regulator transistor(s) (aka pass transistors) but 
prior to the voltage-regulation sense point.
A transistor senses the voltage across this R.
As the output current increases, the voltage across the current-sense R 
increases, at some point the transistor starts to turn

Re: A little power circuit explanation please

[dwight via cctalk]

The regulator needs about 2.5 to 3 volts head room. The circuit is what is 
often called a boost circuit. If my calculations are right, it should produce 
about 15.5 to 16V on C10. This gives the regulator enough over voltage to work 
as a regulator. If the supply you have is not regulated it won't be able to be 
used directly.

TR2 and L1 transformer form an oscillator. When TR2 conducts, it causes a field 
to build up in L1. When TR2 turns off, the field in L1 tries to collapse. The 
voltage build up until the diode conducts charging C10. This is often called 
fly-back. Coils like to keep conducting at a constant rate. Since TR2 turns 
off, the coils voltage will continue to rise until it finds a path to send the 
current ( the diode ).

When the voltage gets high enough across the resistor divider, R16/R15, TR3 
turns off. This removes the bias needed to turn on TR2, shutting down the 
oscillation.

If the voltage on C10 drops to the point that TR3 conducts, the oscillation 
will start again, boosting the voltage on C10 again.

Dwight



From: cctalk  on behalf of Adrian Graham via 
cctalk 
Sent: Wednesday, August 23, 2017 12:33:44 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: A little power circuit explanation please


> On 23 Aug 2017, at 00:49, Rob Doyle via cctalk  wrote:
>
> It's a little switching power supply.  It steps up the 9V input voltage to 
> something a few volts greater than 12V to feed the 12V regulator.
>
> If your 12V is correct, it is probably working.
>

This is from 2 months ago but I was puzzling over the 12V circuit in this 
particular machine and also maybe suffering from a red herring since the PSU I 
was using is from a ZXSpectrum+2 which is an unregulated 12-14V lump so the 
coil was already being fed 12V.

A

> Rob.
>
> On 8/22/2017 4:30 PM, Adrian Graham via cctalk wrote:
>> Hi folks,
>> Failing Atari PSU aside I remembered a question I had ages ago but never 
>> posted about the power circuit of another 80s home micro, the Enterprise 64. 
>> This machine is powered by a 2A 9V unregulated PSU and internally there’s a 
>> pair of 7805s and a 78L12 to smooth things out.
>> There’s also a small transformer coil in there too (L1 on the following 
>> schematic) and I’m not entirely sure what it’s for. Here’s the schematic of 
>> the original circuit, any enlightenment gratefully received since I have an 
>> Enterprise 64 with a dead coil :)
>> http://www.binarydinosaurs.co.uk/ep64PowerRegulators.png

[http://www.binarydinosaurs.co.uk/ep64PowerRegulators.png]


>> Cheers!
>> —
>> Adrian/Witchy
>> Binary Dinosaurs - Celebrating Computing History from 1972 onwards
>

Re: DCC-116 E / DATA GENERAL NOVA 2/10 / Nixdorf 620 - Restoring and restarting

[Brent Hilpert via cctalk]

On 2017-Aug-23, at 6:17 AM, Dominique Carlier via cctalk wrote:
> Here is the situation.
> 
> The + 5V 12A that collapses comes out from pins 10-14 / 36-40, the other + 5V 
> 12A (pins 15-22 / 36-40) never goes down.
> 
> All that I surrounded in green on that image (1950×2361, zoomable) are the 
> components that I tested on the power supply G2, A3 motherboard, regulation 
> board and heatsink A1 + A2:
> http://www.zeltrax.com/classiccmp_forum/psu_g2_test/g2_tested_components.jpg
> 
> To eliminate some doubts and because I do not have some spare parts on hand, 
> I switched the modules A1 and A2, same result. Idem with the transistors 
> 2N2905, same result.
> The result is always the same : it's always the +5V on pins 10-14 / 36-40 
> that collapses, never the other output.
> 
> Some resistors are not yet tested is because these must be de-soldered for a 
> valid test, but the printed circuit is very fragile and many component have 
> legs bent into the weld.
> 
> Except for the not tested components (among others the LM376, the rectifier 
> diodes) At this stage I start again to suspect a little everything. The 
> famous large capacitors of the power supply (C1 to C4). But also a possible 
> problems on the boards of the computer itself.
> 
> As one of you mentioned, the hypothesis of shorted decoupling capacitors on 
> the boards could put the power supply in default.
> 
> Note that the machine runs normally with the CPU board, three core memory 
> boards (400w each) + two multiplexing boards for terminals + the printer 
> board.
> If I add only one of these remaining board:
> - Disk Pack Controller
> - 9-track tape Controller
> - "scanner" board (also for terminals)
> 
> -> Power Fail.
> 
> Note that : if I only connect the CPU and the disk pack controller card: 
> Power Fail too !!
> 
> What makes me doubtful about this scenario is that I can not imagine that 
> these three boards, each causing the Power Fail, could fail simultaneously. 
> Remember that the first time I powered up the beast (one big hour), the 
> machine was working with all the boards and Power Fail appeared at once.
> I have not retested since but also note that by adding an external power 
> supply just for the deficient + 5V , the machine has restarted and even 
> booted the operating system.
> 
> If you have another ideas? LM376?


Am I correct in inferring that this machine (the processor) has four +5V 
regulators?:  it appears there are 2 power supply chassis (rear photo), each 
with 2 regulators,
or are those 2 chassis not identical and there are only to two +5 regulators?

Either way, is it documented or has it been mapped out how the regulators are 
distributed to the bus/backplane slots?
If not, I would suggest doing so to start with, so you know what slots & boards 
each regulator is supplying power to.

Two possibilities come to mind:
- One board, perhaps the CPU board from what you describe, has a fault 
increasing it's current draw.
 Without other boards plugged in on the same regulator, it's within the 
current capabilities of the regulator and 'appears' fine.
But with another board, the current draw is excessive for the regulator 
and current limiting kicks in.

- How is the backplane for this machine organised: as a pure bus, or 
with dedicated slots for specific boards?
Even if it is a bus structure, there might be requirements/limits on 
board combinations to distribute the load amongst the regulators.
Might the machine have been misconfigured by someone moving boards 
around, so that 2 heavy load boards end up on the same
regulator and send it into current limiting?

A minor comment regarding the components in the power supply: Q13 is a stage in 
the regulator drivers and as consequential as other components such as Q2.

FS: Prototype Glitch Works Ohio Scientific Universal RAM Board

[systems_glitch via cctalk]

link: http://www.ebay.com/itm/272817996082

I'm selling some of the prototype boards for my GW-OSI-RAM1 Universal 128
KW RAM board. This board provides up to 128 KW (64 KW without memory
management) of static RAM on the Ohio Scientific bus. It supports a 12-bit
word size and is compatible with the Ohio Scientific 560Z "Processor Lab"
in PDP-8 mode. It also includes a prototyping area, and a header for
mezzanine display boards. Included with the auction is a Hex Lamp Register
and an Octal Lamp Register, which can be mounted directly to the
GW-OSI-RAM1 or used remote on a cable (e.g. for a front panel).

This is a pre-production board, the most significant difference is that it
lacks a corner mounting hole, which can be drilled if needed (no circuit
traces run under its location). The other differences are minor. See
auction link for full description!

Thanks,
Jonathan

Re: DCC-116 E / DATA GENERAL NOVA 2/10 / Nixdorf 620 - Restoring and restarting

[Dominique Carlier via cctalk]

I put the answers in your message

23/08/2017 20:22, Brent Hilpert via cctalk wrote:


Am I correct in inferring that this machine (the processor) has four +5V 
regulators?:  it appears there are 2 power supply chassis (rear photo), each 
with 2 regulators,
or are those 2 chassis not identical and there are only to two +5 regulators?

I myself have trouble understanding and for good reason:

The power supply Gl provides :

   - unregulated +15V
   - unregulated -15V
   - regulated -5V
   - regulated +15V
   - regulated +5V voltages
   - a 30V peak-to peak voltage
   - a time delayed (sequenced) outputs; MEM OK, +5V OK and Power Fail

The sequenced outputs are such that upon power turn-on, first the +5V OK 
occurs, then MEM OK, followed by Power Fail. Upon power turn-off or when 
input power is lost, first the Power Fail goes low, then MEM OK and then 
+5V OK goes down.


The G2 type Power Supply provides :

   - unregulated +15V
   - unregulated -15V
   - two distinct regulated +5V
   - regulated -5V
   - a 30V peak-to-peak voltage
   - a time delayed Power Fail and +5V OK signals



Either way, is it documented or has it been mapped out how the regulators are 
distributed to the bus/backplane slots?

No

If not, I would suggest doing so to start with, so you know what slots & boards 
each regulator is supplying power to.

I would like to but ... here is the back-plane:

http://www.zeltrax.com/classiccmp_forum/psu_g2_test/backplane.jpg


Two possibilities come to mind:
- One board, perhaps the CPU board from what you describe, has a fault 
increasing it's current draw.
 Without other boards plugged in on the same regulator, it's within the 
current capabilities of the regulator and 'appears' fine.
But with another board, the current draw is excessive for the regulator 
and current limiting kicks in.
Possible, but these 3 boards, controller for tape, disk pack, scanner 
(terminal), seem to be more greedy than the others (bad decoupling 
capacitors ?)

- How is the backplane for this machine organised: as a pure bus, or 
with dedicated slots for specific boards?

Dedicated slots for specific boards

Even if it is a bus structure, there might be requirements/limits on board 
combinations to distribute the load amongst the regulators.
Might the machine have been misconfigured by someone moving boards around, so 
that 2 heavy load boards end up on the same regulator and send it into current 
limiting?
Unlikely, the stickers on the chassis indicate the location of the 
boards, this seems to be like that since factory.

A minor comment regarding the components in the power supply: Q13 is a stage in 
the regulator drivers and as consequential as other components such as Q2.

Do you think that Q12 (linked to defective A1 / + 5v) could be the culprit?

Why women were the first computer programmers

[Kevin Parker via cctalk]

This most interesting article appeared in The Age (Melbourne) today.

 

Thought it might be of interest to other list members.

 

http://www.theage.com.au/lifestyle/life-and-relationships/careers-and-money/women-were-the-first-computer-programmers-then-men-crowd
ed-them-out-20170822-gy1e8r.html

 

 

 

Kevin Parker

 

EMA Links on a G104 Sense/Inhibit board

[Rod Smallwood via cctalk]

Does anybody know how the EMA links should set on 4 x 4K G104 boards
For example
 EMA
    0 1 2

  Field 0    IN    IN   IN

  Field  1    ? ? ?

  Field  2    ? ? ?

  Field   3   ? ? ?


Rod Smallwood


--
Wanted one pdp-8/i rocker switch leaver to copy.

Re: Why women were the first computer programmers

[Al Kossow via cctalk]

On 8/23/17 5:17 PM, Kevin Parker via cctalk wrote:
>  
> 
> http://www.theage.com.au/lifestyle/life-and-relationships/careers-and-money/women-were-the-first-computer-programmers-then-men-crowd
> ed-them-out-20170822-gy1e8r.html

"Nathan Ensmenger has observed"

he's written a whole book on the subject "The Computer Boys Take Over"
https://mitpress.mit.edu/books/computer-boys-take-over

Re: EMA Links on a G104 Sense/Inhibit board

[Ian S. King via cctalk]

On Wed, Aug 23, 2017 at 5:40 PM, Rod Smallwood via cctalk <
cctalk@classiccmp.org> wrote:

> Does anybody know how the EMA links should set on 4 x 4K G104 boards
> For example
>  EMA
> 0 1 2
>
>   Field 0ININ   IN
>
>   Field  1? ? ?
>
>   Field  2? ? ?
>
>   Field   3   ? ? ?
>
>
> Rod Smallwood
>
>
> --
> Wanted one pdp-8/i rocker switch leaver to copy.
>
> It's in the prints, which are available on BitSavers.  That's where I
found it last time I did this.


-- 
Ian S. King, MSIS, MSCS, Ph.D. Candidate
The Information School 
Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical
Narrative Through a Design Lens

Principal Investigator, "Reflections on Early Computing and Social Change",
UW IRB #42619

Archivist, Voices From the Rwanda Tribunal 
Value Sensitive Design Research Lab 

University of Washington

There is an old Vulcan saying: "Only Nixon could go to China."

Re: Why women were the first computer programmers

[Brian Walenz via cctalk]

On Wed, Aug 23, 2017 at 8:59 PM, Al Kossow via cctalk  wrote:

>
> "Nathan Ensmenger has observed"
>
> he's written a whole book on the subject "The Computer Boys Take Over"
> https://mitpress.mit.edu/books/computer-boys-take-over
>
>
And:

"Recording Gender", Janet Abbate (also mentioned in the article)
https://mitpress.mit.edu/books/recoding-gender

"Programmed Inequality", Marie Hicks
https://mitpress.mit.edu/books/programmed-inequality

b

Re: Why women were the first computer programmers

[Rod Smallwood via cctalk]

On 24/08/2017 04:10, Brian Walenz via cctalk wrote:

On Wed, Aug 23, 2017 at 8:59 PM, Al Kossow via cctalk 
wrote:
"Nathan Ensmenger has observed"

he's written a whole book on the subject "The Computer Boys Take Over"
https://mitpress.mit.edu/books/computer-boys-take-over



And:

"Recording Gender", Janet Abbate (also mentioned in the article)
https://mitpress.mit.edu/books/recoding-gender

"Programmed Inequality", Marie Hicks
https://mitpress.mit.edu/books/programmed-inequality

b
Many of the first computers ie people who performed computations were 
indeed women.

Hence they knew the steps involved in proceeding from data to answer.
When it came time for computations to be performed by a machine it would 
be their job to get the machine to repeat what they did.


I am all for female equality (but not superiority)

The main reason for the unbalance is the same in all work situations.
Its called Maternal Dropout.
Women are genetically programmed to be mothers and child care specialists.
They have a built in urge to do so. So often expensive education or 
training is wasted by this compulsion.


They are just good at single simple or multi-step complex repeated tasks 
or multi tasking.
These are the main requirements for this vital job. They will all tell 
you that is the case


Once programming moved from formal analysis and form filling eg COBOL 
into an interactive creative activity requiring unitary focus women had 
to work much harder to compete.


Can women be good programmers. Certainly, but they are hampered by 
natural forces that they have to overcome.

Men just move into the vacuum caused by this situation.

Rod









--
Wanted one pdp-8/i rocker switch leaver to copy.

Re: Why women were the first computer programmers

[Josh Dersch via cctalk]

On 8/23/2017 9:14 PM, Rod Smallwood via cctalk wrote:




On 24/08/2017 04:10, Brian Walenz via cctalk wrote:
On Wed, Aug 23, 2017 at 8:59 PM, Al Kossow via cctalk 

wrote:
"Nathan Ensmenger has observed"

he's written a whole book on the subject "The Computer Boys Take Over"
https://mitpress.mit.edu/books/computer-boys-take-over



And:

"Recording Gender", Janet Abbate (also mentioned in the article)
https://mitpress.mit.edu/books/recoding-gender

"Programmed Inequality", Marie Hicks
https://mitpress.mit.edu/books/programmed-inequality

b
Many of the first computers ie people who performed computations were 
indeed women.

Hence they knew the steps involved in proceeding from data to answer.
When it came time for computations to be performed by a machine it 
would be their job to get the machine to repeat what they did.


I am all for female equality (but not superiority)

The main reason for the unbalance is the same in all work situations.
Its called Maternal Dropout.
Women are genetically programmed to be mothers and child care 
specialists.
They have a built in urge to do so. So often expensive education or 
training is wasted by this compulsion.


They are just good at single simple or multi-step complex repeated 
tasks or multi tasking.
These are the main requirements for this vital job. They will all tell 
you that is the case


Once programming moved from formal analysis and form filling eg COBOL 
into an interactive creative activity requiring unitary focus women 
had to work much harder to compete.


Can women be good programmers. Certainly, but they are hampered by 
natural forces that they have to overcome.

Men just move into the vacuum caused by this situation.


Well, this is the stupidest thing I've read today.

- Josh



Rod

Re: Why women were the first computer programmers

[Lyndon Nerenberg via cctalk]

> On Aug 23, 2017, at 9:27 PM, Josh Dersch via cctalk  
> wrote:
> 
> Well, this is the stupidest thing I've read today.

"Do Not Feed The Troll" should go without saying.  Really.

Re: Why women were the first computer programmers

[Lyle Bickley via cctalk]

On Wed, 23 Aug 2017 21:45:12 -0700
Lyndon Nerenberg via cctalk  wrote:

> > On Aug 23, 2017, at 9:27 PM, Josh Dersch via cctalk
> >  wrote:
> > 
> > Well, this is the stupidest thing I've read today.  
> 
> "Do Not Feed The Troll" should go without saying.  Really.

If this list becomes another partisan political list - I'm out of
here...

Lyle
-- 
73  AF6WS
Bickley Consulting West Inc.
http://bickleywest.com

"Black holes are where God is dividing by zero"

Re: Searching for a Sequent (Ian Finder)

[Michael Thompson via cctalk]

>
> From: Ian Finder 
> Subject: Searching for a Sequent
>
> Reiterating my yearly wanted post for a Sequent Symmetry of any kind. This
> is the first system I ever got root on- I'd love to find one some day.
>
> If you have any leads, please let me know.
>
> Thanks,
>
> - Ian
>
> --
>Ian Finder
>(206) 395-MIPS
>ian.fin...@gmail.com
>

I had to move two Sequent Symmetry 5000s last week so we could assemble
some new pallet racking in the RICM warehouse. I have another RAID for them
in my garage. We only need one for show. What do you have to trade for it?
DEC equipment?

http://www.ricomputermuseum.org/Home/equipment/sequent-5000

--
Michael Thompson

need adv. material; and promo for Cobalt CUBE and the 1 u server too!

[Ed via cctalk]

need  adv. material; and promo  for Cobalt CUBE and the  1  u  server  too!
 
Have these 2  units want to make a nice display with them...  need  to 
dress the background etc...
 
thanks  in advance - 
 
Ed#

Re: Why women were the first computer programmers

[Brent Hilpert via cctalk]

On 2017-Aug-23, at 9:55 PM, Lyle Bickley via cctalk wrote:
> On Wed, 23 Aug 2017 21:45:12 -0700
> Lyndon Nerenberg via cctalk  wrote:
> 
>>> On Aug 23, 2017, at 9:27 PM, Josh Dersch via cctalk
>>>  wrote:
>>> 
>>> Well, this is the stupidest thing I've read today.  
>> 
>> "Do Not Feed The Troll" should go without saying.  Really.
> 
> If this list becomes another partisan political list - I'm out of
> here...



I was going to have something to say about the one aspect of the original 
article that would be on-topic:
it's historical assessment of the industry. I'll skip the full version as it 
would likely lead to more acrimony.

The article was primarily political, as historical presentation it is empty.

Rod expressed an opinion/assessment based on what I will presume to be his 
experience and observation from years in the industry.

The utterly empty attacks of "troll" and "stupid" rise no higher than being 
partisan and political.