Kepco ATE6-10M power supply issues

[nsd_c]

Hi all,

I have three Kepco ATE 6-10M power supplies of varying vintage that I acquired from a surplus electronics store. These are quarter-rack 6A, 10V power supplies with analog readouts ('M' suffix as opposed to 'DM'--they're phasing out the analog read-outs in favor of digital readouts). Kepco still makes these and even sells the service manuals, but the pricing for the service manuals is... well, not financially viable for me at $200, and they seem to indicate that a separate service manual could be required for different generations of the same model supply (costing $200 each).

One of the supplies seems to work just fine: it smoothly and cleanly (and very linearly) ramps to the setpoint voltage on start-up; the crow-bar works and trips the breaker; and the current/voltage modes both work as you'd expect.

The other two of these are flaky: in the milliseconds that follow power-up, I see massive voltage transients (very narrow) on my scope, maybe like 50V peak, but it's hard to measure these and I don't want to risk damage to my scope by re-testing this (not without a 100x probe anyway--perhaps I need to make a crude one of these). On one of the bad two, the current mode is flaky, though I suspect it might be just a dirty pot: shorting the power supply output with an ammeter and cranking up the current dial causes the power supply to rapidly flit back and forth between current and voltage modes. It seems like the wiper is intermittently losing contact, causing the power supply to "fail-unsafe," wherein current spikes up, probably trying to hit the full 10A. (E.g., with the current set to ~3.5A and fiddling with the current knob, I got it to go into voltage mode for a fraction of a second, and my DMM captured a current spike of ~5A.)

The units are both quite old and could probably use with all of the electrolytics being replaced. I don't yet have an LCR or ESR meter that I can test the caps' ESR in-circuit with yet (though I do have some DMMs with the ability to measure capacitance). Going by the date code on an op amp in all 3, dates are 1980, 1984, and 1989.

Perhaps someone on the forum here has access to the schematics and might be able to help...?

[coromonadalix]

The Ate service manual can be found on the Web for free, I did search a lot to find them

Edit : luckily i still have some links, i have all the rack sizes.

I did change the pots in mine for 10 turns ones,  better precision adjustments, and a better / bigger pot knobs.

I hacked the analog meters for 4 1/2 digits meters panels, +/- 20$ each.  had to do some slight panel fitting, and the panels meters have their own individual supply.  For the current panel, i take the voltage readings on the rear terminal block, since the psu has an current to voltage output pin, this value is very reliable and precise.

IMPORTANT they each need to have floating supplies, not ground related.

And finally i added an variable AC fan controller, boy this puppy is noisy as hell.


For electronic, i did recap the unit entirely (not even tried to test the caps before) and changed the main bank capacitors to newests ones (slightly bigger capacity in capacitance).



Sorry  my unit is on the side


Service Manual LINK : ( 3 part file to self extract click on "0 1 and 2" ) :  https://www.eserviceinfo.com/downloadsm/34154/Kepco_Kepco%20ATE%201/4%20rack.html

[nsd_c]

Hi coromonadalix,

Thanks so much for the information!

I anticipate that I'll start by putting together a BOM of all new electrolytics and probably just go ahead and replace all of those when I have the time.

I did change the pots in mine for 10 turns ones

That's interesting that yours did not have 10 turn pots--all three of mine have these and seem to be from the factory.

And finally i added an variable AC fan controller, boy this puppy is noisy as hell.

That's a good idea, although probably more effort than I'd like to put into these. Also, I find the noise from the fans in my units to be tolerable.

[xyloeye]

I have an old JQE 55 power supply. In this one, the current regulation circuit quit working. Still puts out power but no current regulation. There is a component in the circuit marked AV. It's an ancient op amp used to amplify the error signal. It has 6 terminals instead of the usual 5. I can't find any specs on this thing and, like you, not interested in paying $200 for a service manual for an old supply worth about 28 cents. Do you have any idea what could be used to replace this op amp? Thanks.

[duak]

If you don't have a manual, there's one here: http://exodus.poly.edu/~kurt/manuals/manuals/Other/KEPCO%20JQE55-2%28M%29%20Instruction.pdf

It has a schematic and parts lists but no more info on the mysterious AV.  It looks like an op amp of some sort.  If it's bad it should be possible to use a modern equivalent but you'd have to make sure it can handle the voltages.

If the current limit isn't working, I'd check all the jumpers on the back and then the circuitry around Q3 & Q4.  In some ways it's easier to have discrete parts rather than chips because you test each bit for shorts and opens in circuit.

Cheers,

[coromonadalix]

Could you take a photo of the ic  or section where it is ?   i think  an op amp with an compensation and or trim pin can or could be put there, the problem is  to find an correct substitute

Nothing came out  searching the PN : 250-0013

only thing ive found : http://www.parttarget.com/Kepco-Inc_nsn-parts_250-0073_250-0193.html            the fifth item down

some specs
250-0013

2500013   5962-00-405-1390   Microcircuit, Linear   Inclosure Configuration: CAN
Operating Temp Range: -55.0 to 125.0 deg celsius
Features Provided: Monolithic

And a lot for almost nothing specs :
-----------------------------------------------------------------------------------------------------------------------------------
5962-00-405-1390 Features
MRC           Parameter                          Characteristics
ADAR   Body Outside Diameter          0.620 inches maximum
ADAU   Body Height                          0.400 inches maximum
AFGA   Operating Temp Range         -55.0/+125.0 deg celsius
AFJQ   Storage Temp Range                 -65.0/+150.0 deg celsius
CBBL   Features Provided                 Monolithic
CQSJ   Inclosure Material                 Plastic
CQSZ   Inclosure Configuration          CAN
CQZP   Input Circuit Pattern         2 input
CSSL   Design Function and Quantity             1 amplifier, operational, general purpose
   
and a reference to this company ??         Advanced Analog Inc.

[coromonadalix]

With tons of search and useless and going nowhere links

you av ic (250-0013) seems to be this number :  DMS 80062B

Never saw that number ??


I saw theses :  maybe they can be an substitute,  the mysterious "AV" seems a module ??  we need pictures  loll
LT1028/LT1128
AD744

[xyloeye]

Thanks for the replies.That sort of info is all I've been able to find on this mystery "microcircuit". All the components on the board check OK but there are some strange voltages. Here's a picture.

[coromonadalix]

The final answer would be to open this can/case and try to make the circuit out of it,  there is enough op amps models on this world who could fit ........ i hope its not "potted"

I only think of something : maybe this psu was designed at start for military purposes    never saw in my life a special design like this unless the clear intention was to obscure certain parts ?

[xyloeye]

Yeah, thanks. I hadn't thought of the military possibility. Could be matter of national security, I suppose. But I think you're right - I'll take it apart, although it looks like it could be potted on the bottom. I'll report back if I ever figure it out.

[Kleinstein]

The case looks a little like the old style OPs, e.g. from the 1960s, when they came in similar cases. There was even a kind of standard pin-out.

[coromonadalix]

Maybe another possibility :   its build like this for thermal stability still hoping its not "potted"