Author Topic: Xantrex/Sorensen XHR 40-25 schematic? (Read 3641 times)

ifonlyeverything · « **on:** November 17, 2023, 03:02:04 pm »

I've recently come into possession of a non-working Xantrex/Sorensen XHR 40-25 power supply. Does anyone happen to have a schematic? I tried searching Google but I can only seem to find an operating manual which doesn't include a schematic. The XKW series service manual/schematic is available but just looking at the board reveals significant differences...

coromonadalix · « **Reply #1 on:** November 17, 2023, 04:17:26 pm »

EDIT see further away

~~so far nothing from xantrex has ever leaked, or maybe some as you suggest, witch is rare ...~~

apparently maybe some lambda TDK may have some similarities, not sure for Sorensen

ifonlyeverything · « **Reply #2 on:** November 17, 2023, 04:25:51 pm »

That's unfortunate, I'll look around for anything TDK that might be comparable.

For anyone who has never seen the inside of these.... very EFFICIENT use of space near the output.

ifonlyeverything · « **Reply #3 on:** November 17, 2023, 06:51:37 pm »

If anyone is familiar with these beasts, I'd appreciate some hints on how the main DC-DC topology works.

I believe there's a PFC boost upstream. I can see the mains rectifier and then two FETs and two diodes in parallel on the PFC side. On the downstream DC-DC I see four FETs with bootstrapped gate drivers (IR2110), followed by the transformer, output inductor, and output capacitors. But I'm not seeing any rectifiers?

coromonadalix · « **Reply #4 on:** November 18, 2023, 01:47:46 am »

some power supplies use some kind of a buck boost / buck down configuration / pwm configuration like / or ac phase control and have another section called the main regulator section

a mix of switching and linear modes ... not sure if xantrex ones use something like this ??

on the bus bar you have a big black rectangle component, could be an scr, triac or bridge rectifier or even an big IGBT witch would made sense with the nearby ic's, and the thansformer who is in reality an huge inductor seems to confirm the operation

the linfinity sg3524 is a classic pwm ic
the uc3842 is a 500khz pwm ic too

IR2110/IR2113 are high voltage, high speed power MOSFET and IGBT drivers

ifonlyeverything · « **Reply #5 on:** November 18, 2023, 03:50:10 am »

Quote from: coromonadalix on November 18, 2023, 01:47:46 am

on the bus bar you have a big black rectangle component, could be an scr, triac or bridge rectifier or even an big IGBT

Wow, nice call. I thought it was just some sort of insulator but I checked it with my multimeter and it shows a 0.33V forward voltage on diode mode. So it apparently works, I guess, but I'd like to know WHAT part it is. Of course the identifier is on the fucking bottom, where it can't be seen without taking off the (+) bus bar... which means breaking the EMI ferrite glued around the bus bar in half and de-soldering and unbolting the clusterfuck that is downstream of the EMI ferrite. The engineers definitely did not design this with serviceability in mind.

edpalmer42 · « **Reply #6 on:** November 18, 2023, 06:40:03 am »

Here's the service manual for the XHR series.

http://www.ko4bb.com/getsimple/index.php?id=download&file=06_Misc_Test_Equipment/Xantrex/Xantrex_XFR_Power_Supply_Manuals_and_NI_Drivers/Xantrex_XHR_Xantrex_XHR_600W_1KW_Service_Manual_TM-XR01-XN.pdf

Ed

ifonlyeverything · « **Reply #7 on:** November 18, 2023, 12:14:56 pm »

Quote from: edpalmer42 on November 18, 2023, 06:40:03 am

Here's the service manual for the XHR series.

http://www.ko4bb.com/getsimple/index.php?id=download&file=06_Misc_Test_Equipment/Xantrex/Xantrex_XFR_Power_Supply_Manuals_and_NI_Drivers/Xantrex_XHR_Xantrex_XHR_600W_1KW_Service_Manual_TM-XR01-XN.pdf

Ed

THANK YOU.

edit: The manual doesn't disclose the exact part # but their internal part # (CR-2040-PT) and description (ultrafast 200A 400V) appears to correspond to MURP20040CT.

coromonadalix · « **Reply #8 on:** November 18, 2023, 01:41:55 pm »

basicly the psu topology is: they rectify the AC, PFC control/stabilize it in some cases, and with this huge DC line they PWM it ...

oh ho check "xantrex" on the given website there is more

i did use xantrex psu's in the past, very efficient and compact, while being heavy loll

years ago when they broke, it was a dud to repair them, now i see that we can do repairs at some point ... i admit i never redone any search my bad

and you seem to have some software too for visa or control ??

Chris56000 · « **Reply #9 on:** November 18, 2023, 03:52:08 pm »

K04BB are taking a hell of a long time to sort out the manuals from their "Recent Uploads" directory – some of the files in there haven't been made available for download in over two months!

Chris Williams

edpalmer42 · « **Reply #10 on:** November 18, 2023, 08:12:58 pm »

Quote from: Chris56000 on November 18, 2023, 03:52:08 pm

K04BB are taking a hell of a long time to sort out the manuals from their "Recent Uploads" directory – some of the files in there haven't been made available for download in over two months!

Chris Williams

Remember that KO4BB isn't a group or a company. It's a guy who pays for the storage space and bandwidth on his own and maintains the system in his spare time when the rest of his life allows it. All things considered, I think he's doing a great job!

By the way, when did you last send a donation to help him cover his costs? I sent him $50 a while back and he seemed very grateful. Makes me wonder if that was an unusual occurance.

Ed

armandine2 · « **Reply #11 on:** November 22, 2023, 02:23:43 pm »

If you don't want a scan, another link, worked for me - manuals - but no schematics

https://www.programmablepower.com/

https://www.programmablepower.com/products/dc-bench-power/xhr-series

[edited to manufacturer's links]

coppercone2 · « **Reply #12 on:** November 22, 2023, 05:28:21 pm »

lol check those sockets my sorensen (30V30A) had a bad socket on a op amp , even after I resocket it and clean the chip out etc.

nonsense happens until you push on the chip then it worked fine. if just wanna try some random whatever replace those socket
put some berylium copper or bronze pin sockets in there

i wonder if it could be because they got bus bar and big heat sinks like on the PCB

you can also disconnect the limiter circuitry totally (trimpot stuff) by disconnecting a resistor maybe. it should work fine. gets rid of that variable

as usual check the rails on the IC first before you start messing with the high current portion. I also took mine apart and cleaned/greased the bus bars and bolts etc with deoxit grease or liquid depending on ease

but If I had to do another sorsensen switcher, I would literarly replace all the sockets before working on anything else, and I would not bother trying to test the socket (probobly lies when you probe it, mine did)... the whole thing with the probe on the bottom of the leg or under the PCB and a probe on the chip to measure continuity is BS for dodgy sockets that is not reliable troubleshooting IMO. i know there is some socket master voodoo priests in old computer repair but just IMO fucking replace that BS its not worth trying to analyze, you aint trying to preserve the vintage of some atari lol

here, take this

https://www.digikey.com/en/products/filter/sockets-for-ics-transistors/ic-sockets/409?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALGGABxwDsIAuoQA4AuUIAyuwE4BLAHYBzEAF9CtAMyIQKSBhwFiZENOlwwAJkaENW7duZtOkHv2FjJIAKx05CpXkIlI5CgAZbnz8ZYgHFy8gqISUhqejmhYLqrulNT02hQg%2BjQ09GAI6TS22jRp6hkU%2BSaBZhah1lL0WtGKsSpu5NI%2BdTBFXgXSEFLlQeYhVuHgdbLQ8jHKrmq9cBRZRdI0MLYUCAGDVSM2YHWMk05Nswnzi33FaxsDlcNhNgC0xkdQ-ACuzWq2zOI2P5NWFAwGwgZAfDZOpMBAATLhgSJFbb3MSEdgAT1YuC4MOwKD%2BQA

ifonlyeverything · « **Reply #13 on:** November 23, 2023, 01:01:20 am »

Cleaned up the PCB a bit, didn't see any blown FETs, PCB scorch marks, or blown fuses. Need to get a light bulb limiter set up before I start investigating the power electronics further, and I think I want to test the control board separate since it's low voltage stuff (or just build an op amp test jig since it's all socket mount.) coppercone2 I'll be sure to focus on the sockets, some of them do look a little janky. Also managed to drop a fucking screw between that output capacitor clusterfuck, so I had to pull a few caps off to get the screw out -- needle nose pliers just jammed it in deeper. Might as well replace the output caps while I'm at it.

In the meantime I'm still studying the schematic, trying to understand how it all works. I noticed the marketing material claims ZVS. Is this actually ZVS/soft switching? I'm no SMPS expert but the full bridge IC is just an SG3524 and I'm not seeing any evidence of any sort of ZVS detection circuitry... unless I'm missing something obvious?

coppercone2 · « **Reply #14 on:** November 23, 2023, 01:08:20 am »

what was the problem with it to begin with? Not really sure how they work too well. I kinda figured out the feedback loop and figured where the fault might be.

but... power rails ok?

and my socket looked fine, it even removed OK, its just messed up. those socket suck because they are the 2 leaf things not the little hole

but you got a much harder supply because its 1kV. Mine is 30V. Anything over like 100 volts makes it mad complicated. 1kv exceedingly so. new failure modes for parts. Even resistors can do that shit where they start failing at a high voltage like 750 volts.

Also mine had a mains connector that was not soldered in! it was press fit in for most of its life with almost no solder on the pin. It started arcing on me after I fixed the unit, luckily all it needed was a dash of solder. Sorensen QC must have had a bad day. I had enough HV shit since I fixed the miller dynasty welding machine (it has like 800V rail). Weird shit was going on there, far away insignificant looking components like ceramic caps causing problems.

Honestly the way to test this would be to desolder each part, bias it with HV supply, make sure its OK.. anything on the HV rail IMO can be really suspect but I don't have much experiance with that.

coppercone2 · « **Reply #15 on:** November 23, 2023, 01:17:00 am »

lol if someone made me fix this, I would replace all the silicon on this thing and check all passives under HV and hope it works. stomach ache from thinking about the schematic . the only thing I know is that I would have to buy extra pace desoldering tips for this job

but for BS parts like 317, 347, gates, 351... its not really big money if you are patient and replace. that might give confidence enough to feel like you can trouble shoot it. for the gates that are like 10$ on ebay breadboard test it, but honestly with a desoldering tool, like a 1.5$ op amp.. Id just fuckin replace it.

if you can get it to a specific fault, it might limit the amount of trouble shooting.

probobly the diodes too.

only tip is clean the board from flux as you go along but not too clean and do a final clean when you are done

power transistors too, if they are cheap, replace IMO. If you gotta import it from bulgaria test it

if you do this crazyness, i recommend printing out the entire part list, getting two color of highlighter, and marking parts that might be suspicious with 1 color and another color if tested or replaced. but you need to test the HV parts with some voltage probobly or it might be another unknown.

ifonlyeverything · « **Reply #16 on:** November 23, 2023, 01:29:02 am »

Quote from: coppercone2 on November 23, 2023, 01:08:20 am

what was the problem with it to begin with? Not really sure how they work too well. I kinda figured out the feedback loop and figured where the fault might be.

but... power rails ok?

and my socket looked fine, it even removed OK, its just messed up. those socket suck because they are the 2 leaf things not the little hole

but you got a much harder supply because its 1kV. Mine is 30V. Anything over like 100 volts makes it mad complicated. 1kv exceedingly so. new failure modes for parts. Even resistors can do that shit where they start failing at a high voltage like 750 volts.

Also mine had a mains connector that was not soldered in! it was press fit in for most of its life with almost no solder on the pin. It started arcing on me after I fixed the unit, luckily all it needed was a dash of solder. Sorensen QC must have had a bad day. I had enough HV shit since I fixed the miller dynasty welding machine (it has like 800V rail). Weird shit was going on there, far away insignificant looking components like ceramic caps causing problems.

Honestly the way to test this would be to desolder each part, bias it with HV supply, make sure its OK.. anything on the HV rail IMO can be really suspect but I don't have much experiance with that.

Previous owner said it would click on and off repeatedly with no apparent power. There's only one relay on the PCB (K139) which switches in/out 20 ohms of resistance to slow inrush current. I however didn't plug it in (yet.) Hopefully the problem is isolated to this relay, its power supply or its coil control logic, because these sections don't look TOO daunting.

Mine is only the 40V 25A model, so no worries about high voltage.

coromonadalix · « **Reply #17 on:** November 23, 2023, 02:09:18 am »

you could be surprised, dont assume thet psu is rinning on low voltages

normally the 120vac is rectified to at least 160vdc or doubled 320 347vdc to create a stable dc supply to be pwm'ed to the control stage ...

coppercone2 · « **Reply #18 on:** November 23, 2023, 02:11:19 am »

oh yeah but its not a 1kV regulated output stage thankfully

ifonlyeverything · « **Reply #19 on:** November 23, 2023, 02:22:52 am »

Quote from: coromonadalix on November 23, 2023, 02:09:18 am

you could be surprised, dont assume thet psu is rinning on low voltages

normally the 120vac is rectified to at least 160vdc or doubled 320 347vdc to create a stable dc supply to be pwm'ed to the control stage ...

Oh yeah definitely, the PFC boost stage looks like it's putting out close to 300V.

coppercone2 · « **Reply #20 on:** November 23, 2023, 02:23:48 am »

ok so if the relay is clicking on and off what does that mean.. how to recreate the problem

q215 is a low side driver for the relay. when it closes it energizes. something is causing that to open.u228a.

this is labeled overcurrent

the non inverting input is the input to this relay, the other shit is tied to rail. if rails are fine, so it has some shit going to ground, but the signal comes from r221 475k, which is tied to dc negative master, so the 18V rail goes through 1k1 to opamp input.

that op amp looks like its going into a rC delay for Q215.

so is this just a timer here? i think its also wired to the over voltage or whatever from the chip that connects to the shunt and the PSU

r294 to 297 is maybe a shunt for measuring current, goes into Isense on the chip

yeah idk its getting really complicated.'

But that is a clue, if its going over current protection, that might mean a shorted transistor some where I think... that chip might be measuring fine, and bad transistors are really common on power supply.

you can turn it on and probe that chip to see if its doing what its supposed to be doing. like measuring current and voltage

I think maybe just testing those transistors after the relay might be a good start, to look for damaged power transistors, possibly past the transformer. possibly at the output. i have seen more bad power supplies with just damaged power transistors then damaged control circuits, but I have seen power supplies that have damaged transistors and also control circuits. but the first one is more likely. and its likely if you find a bad transistor the control circuit for it might be damaged not some irrelevant one.

like sorensen has a good name, its considered reliable and high end, more then likely you don't have some deep control fault

it might be a transistor that is also connected to ground.like q114 h bridge

Q166 is like a crowbar or whatever, that abruptly sinks power if there is a fault to protect the output. this is the one you can disconnect and have a functional circuit still. r146 is like the front panel adjuster for the trip point.

test everything semiconductor in the top 1/5 of schematic page 95

coromonadalix · « **Reply #21 on:** November 23, 2023, 08:15:50 am »

Since its driven by u228a

you may have some overcurrent situation / something is current consuming at some point OR
its friend with the under voltage ic u228B .... meaning you seem to / may have a triggering condition

Not sure about r317 r318, if they act as a slight inrush current limitter or "voltage dropper" and all of it is before the current sense resistors ... for the primary section

You have r221 who goes near r317 and goes to this ic u228a, for sure its a sense line return ...

-----

yeah its a tough cookie psu loll, you have some pre-regulation circuit and the power circuit

you have 3 power supply sections, you have the small one (u64) who seems to give gives some clock to U21

, and you have its output line who goes on U287 opto isolator, who goes to U250

U287 must act as an ok supply to start U250

or some clock pulse is driven ?? maybe the 50-60hz detection ?? but it seems autonomous ?? man

you have to decypher circuit parts and try to figure out how they inter connect, in some cases say : you isolate 1 section and subs it with another dc source and try to see where it fails

you have p301 test points ? this is the dc voltage of the 1st power section ...

and the ususals checks for all the small voltages in this psu .. when its possible ... there could be a domino effect, one affect the other ....

factory · « **Reply #22 on:** November 23, 2023, 06:43:29 pm »

These are known as the Glassman LVP series over here, they are 1kW not kV.
We had about a dozen rack mount version at 150V 7A at work, can't remember any dying, the fan packed up in one.

There was however a very nasty fault with one of them, the voltage set pot would jump the output to maximum, when it got to a dead spot on the ten turn pot.

There is a bigger 150V 20A version & a newer 300V 9A unit at work, those can burn stuff very nicely, if you have a fault on the unit under test.

David

Chris56000 · « **Reply #23 on:** December 05, 2023, 07:30:22 pm »

Hi!

Update to my previous post – Manuals on k04bb now available for download!

Chris Williams

NikiG · « **Reply #24 on:** December 12, 2023, 08:05:43 pm »

Hello, you maybe have problem in two components in corner?

coppercone2 · « **Reply #25 on:** December 12, 2023, 11:09:11 pm »

lol where is waldo

watch that fixes it!

ifonlyeverything · « **Reply #26 on:** December 13, 2023, 02:08:48 am »

Quote from: NikiG on December 12, 2023, 08:05:43 pm

Hello, you maybe have problem in two components in corner?

Looks a little toasty, I'll have to check it.

Unfortunately haven't had much time to work on this due to demands of my day job. I also need to order a new set of output capacitors and desolder/individually check the input capacitors and FETs.

coppercone2 · « **Reply #27 on:** December 13, 2023, 03:25:00 am »

a burned out part is like a really strong guess that it might just work if replaced. and whatever that resistor is connected to also.

NikiG · « **Reply #28 on:** December 14, 2023, 07:45:00 pm »

ifonlyeverything · « **Reply #29 on:** April 10, 2024, 11:56:50 pm »

4 months later and I finally have a little free time to dick around with this.

I replaced the capacitor that NikiG identified and fired it up. The relay clicked a bunch of times, the display flickered, the SMPS fired up for a second, and then it went back to flickering the display. I power cycled it a few times. No more relay clicks and the display is flickering. It's not powering up fully as I can't hear the fan run.

I can measure 170V DC across P2 so I know everything upstream is good. U21 (UC3842 SMPS IC) has an unstable VCC-GND voltage, fluctuating between 12V and 13V DC rapidly. I measured the voltage across C38 and I'm getting between 0.8V and 1.0V rather than the expected 18V. I measured the voltage across C35 and I'm seeing 7-8VAC at 60 hz which makes no sense.

This C35 output, I think it's supposed to be 18V, feeds the UC3854 PFC IC and the UC3524 full bridge IC. The UC3842 VREF output feeds the U64 ripple counter, which feeds the UC3524 full bridge IC. I measured this VREF and it's 0.8V to 1V, so nowhere near its intended 5V.

I'm not an expert with SMPS here but I assume something in this UC3842 section is having an issue here. Any suggestions on what I should measure next? I have a scope but I'm a little paranoid of using it since I don't have differential probes.

coppercone2 · « **Reply #30 on:** April 11, 2024, 01:50:19 am »

how are you measuring the flickering voltage?

It bothers me. But its also a SMPSU IC. I don't know if those can make voltage flicker maybe if its switching something rapidly. I think that there is a problem here, but pulse loads can do weird things.

This usually means there is a bad capacitor. I assume its a linear regulator powering this IC?

If you see that much AC on a filter capacitor it might mean the capacitor is bad. Of course someone that works with that chip might know for sure.

8VAC on top of a digital chip power supply rail seems like way too much

Fix that because it can make other things go really screwy. Like everything on that rail is suspect if its behaving like that. Or at least verify its normal some how

ifonlyeverything · « **Reply #31 on:** April 11, 2024, 10:31:25 am »

Quote from: coppercone2 on April 11, 2024, 01:50:19 am

how are you measuring the flickering voltage?

It bothers me. But its also a SMPSU IC. I don't know if those can make voltage flicker maybe if its switching something rapidly. I think that there is a problem here, but pulse loads can do weird things.

This usually means there is a bad capacitor. I assume its a linear regulator powering this IC?

If you see that much AC on a filter capacitor it might mean the capacitor is bad. Of course someone that works with that chip might know for sure.

8VAC on top of a digital chip power supply rail seems like way too much

Fix that because it can make other things go really screwy. Like everything on that rail is suspect if its behaving like that. Or at least verify its normal some how

I measured the 12-13V DC between pin 7 (VCC) and pin 5 (GND) of the UC3842. There's no linear regulator. The P2 connector is seeing 170V DC, which is fed through R14 to the VCC pin 7 of the UC3842. The auxiliary winding presumably takes over and feeds rectified voltage (diode CR16 and capacitor C22) to the IC, once it successfully starts up.

This is all further complicated by U64 which is acting as the oscillator for the UC3842 (pin 7 of U64 to pin 4 of the UC3842)... as well as acting for the oscillator for the UC3854 PFC IC and the UC3524 full bridge IC. I barely understand how U64 works but I think it implements a startup delay in addition to acting as the oscillator... so I have no idea how there is synchronization between UC3842 pulsing on with 170V DC, the auxiliary winding taking over, and the UC3842 somehow outputting a VREF stable enough to power U64.... which then takes some time to finally generate the oscillator pulse that feeds UC3842 RT/CT inputs... which it presumably needs BEFORE the auxiliary winding can fire?

Maybe I'll try probing the Q11 gate and the Q11 sense resistor, to see if the switching waveform look normal at any point, and to see if excess current (from a short somewhere) is causing the IC to repeatedly loop through overcurrent shutdown and start up.

coppercone2 · « **Reply #32 on:** April 11, 2024, 11:10:33 am »

But you said that is 6VAC on a digital rail that goes to UC3842.

it might have a wide range but VDD pins are usually DC voltages with not much AC component.

Even if its just a transformer secondary thats regulated it should be smoothish I think, not 30% ripple. if I read that right 30% ripple + 1VDC out of a VDC reference regulator means there is a problem. I would start with 30% ripple being a problem

ifonlyeverything · « **Reply #33 on:** April 11, 2024, 11:36:55 am »

Quote from: coppercone2 on April 11, 2024, 11:10:33 am

But you said that is 6VAC on a digital rail that goes to UC3842.

it might have a wide range but VDD pins are usually DC voltages with not much AC component.

Even if its just a transformer secondary thats regulated it should be smoothish I think, not 30% ripple. if I read that right 30% ripple + 1VDC out of a VDC reference regulator means there is a problem. I would start with 30% ripple being a problem

The low AC voltage I measured is across the smoothing capacitor C35 of the rectified auxiliary winding, which feeds the UC3842... as well as the PFC IC, full bridge IC, full bridge gate driver ICs, and several op amp power rails. Maybe I'll measure this with a scope as well. I initially measured it with my DMM, which refused to read anything on VDC but showed 7-8VAC at 60 hz on VAC mode. It has to be an artifact from things hiccuping and my DMM not being able to read fast enough. I have no idea why else I would be seeing 60 hz AC unless something is seriously fucked up.

coppercone2 · « **Reply #34 on:** April 11, 2024, 11:42:37 am »

yeah, the capacitor !!! electrolytic capacitor not smoothing. news at 11

very common for caps to die and not do their job

The only thing that can cause a functioning cap to do this, is if the load is way greater then what that value capacitor can do. Capacitor value in a smoothing circuit is proportional to load. More load = bigger cap to get same ripple

unloaded it should be dead smooth

or the diode

i won't say that this is the only possible explaination, I think there might be some other possibility, but this is a VERY COMMON occurrence if its working as I described

ifonlyeverything · « **Reply #35 on:** April 12, 2024, 11:49:53 pm »

Pulled every electrolytic capacitor on the main PCB and they all tested fine on ESR meter: C22, C28, C35, C37, C39, C41, C77, C90, C100, C108, C289. Pulled Q11 and tested it on my transistor tester, looked fine.

I think my next step is to pull every diode, resistor, and non-electrolytic in this UC3842 circuit block and test for dead shorts. If nothing is bad then I'll pull just replace UC3842 and hope that works, because I have no clue what else it could be other than the transformer being bad (unlikely) or something pulling down the +18P rail (a ton of shit.)

Or maybe I could just unplug it from mains and inject +18VDC from my bench power supply at CR17 and see what kind of current draw I'm getting.

ifonlyeverything · « **Reply #36 on:** April 13, 2024, 04:46:16 pm »

Pulled CR17 and F1, swapped R14 with a 10K resistor temporarily, and powered the downstream size of F1 with +30VDC with a 1A CC limit from my bench power supply. All voltages are looking nice and stable. Plugged in the secondary control board and the front panel, voltages were fluctuating and the front panel was visibly flickering. Unplugged front panel from secondary control board and voltages were still fluctuating. Looks like the problem is isolated to the secondary control board.

coppercone2 · « **Reply #37 on:** April 13, 2024, 06:22:43 pm »

ohhh I see its a totally different form factor then mine. i thought it was the single unit high pizza box

the schematics look very similar. but mine had 0 capability for isolation unless you want to cut traces. All I could do is unplug the GPIB card. I did not think of that trouble shooting technique

I forgot to mention, do you have crappy sockets in there for op amps? Because one of mine had a bad socket for a op amp. they are not machine pin, it had some really dodgy ass leaf socket

pic1 confirms you do have the shitty sockets.

Just thinking about it, flickering is sometimes caused by bad contacts. On those cable harness too. But I can't think of how it would cause the vref voltage to drop down to 20%

if you fix it you might wanna replace them all for 10$ before you put it back together, so you don't explode something later on.

I had the linear one in that form factor, the only thing I renember about it before I threw it out
1) it had something like 5 transistors working together on the output stage for the big power transistor, that is a bunch of 'passives' (do hardly any work with current). One of them broke. I replaced all of them and it started to work. I over tightened a chassis screw and caused a bolt to fry one of them again because a spacer was missing or not engineered in. it fried something again. Then traces started coming off during rework and i threw it out. if the power transistor breaks the ones around it break too
2) one of the wires on the IDC cable (insulation displacement cable) broke and came out of the harness. Clever method to weld the wire to the connector but I don't like it. you can't really poke it back in there, whole cable needs to be replaced or a solder fix has to be made with a external jumper wire. the crimp tool causes it to cold weld to the pin fork. once that breaks it done. its like wire wrap, not a crimp. the crimp tool is expensive

ifonlyeverything · « **Reply #38 on:** April 13, 2024, 09:03:24 pm »

Fed the secondary control board with my bench power supply, the 5V and 9V sections were fine. 18V and -18V had shorts, replaced the linear regulators U238 and U252 and the short went away.

Found out that main A3 board and the secondary A2 can have connection issues because the box headers aren't properly sized, meaning the pins will shift over 1 row... when this happens it will trip the auxiliary supply like before. Not sure if this caused the U238/U252 regulators to blow for the previous owner, but they did not blow for me.

I reassembled A2, A3, and the front panel and made sure A2-A3 connectors mated properly. Fired up the auxiliary power supply with +18VDC from my bench supply and it worked perfectly. All of the buttons on the front panel worked as expected, holding in V/I to set up a commanded V/I worked fine -- no drift in the numbers.

Re-soldered CR17, put F1 back in, swapped R14 for the 68K resistor. Reassembled everything. It fires up, front panel lights up, fans run, and there is an output voltage... but it's not working right.

I click in STANDBY and hold in V/I to set the V and I and the numbers will drift. They did not drift when I was powering it off +18VDC bench supply. I click out STANDBY to enable the output and I can hear a buzzing sound. Not sure if this is expected. Voltage refuses to go over 20V and it jumps around. Current limit is also acting strangely. It looks like the CC and CV limits are being obeyed but it just drifts around and won't stabilize. I'm using resistive loads.

Rear panel SW1 is in default configuration and I have J2 SNS- wired to the negative bus bar and SNS+ wired to the positive bus bar.

So... back to troubleshooting!

Will be sure to double check ALL of the sockets.

coppercone2 · « **Reply #39 on:** April 13, 2024, 09:16:17 pm »

ok but if the regulators were shorted it might mean that there was a shorted load connected to them and that is why they maybe over heated and died after a while. like one of the op amps. or a cap shorted out and went open.

idk how to check the sockets though, replace. I had this bullshit where I pressed it in and it would work. then after i reassembly chassis it stop working. I open it up and push on chip it works again.

its like playing peek a boo with a troll

if you think you fixed anything by messing with the socket just replace the damn thing, its not reliable, i think you can get 30V randomly if the wrong socket goes up. meaning bye bye load (and a reason to fuse your prototypes even if your on a lab suply). i bought like 20 fuse holders and a whole set of fuses so I don't have to worry about malfunctioning opamps burning things

but thankfully when my op amp socket acted up, it dropped down to 3V max. idk how it decide on which set point to fall down to. maybe its built so it goes down to a low level if it fails, but I can't verify this... also it did once go to 17V when set to 15V I think, which caused a fan to burn out (otherwise tolerance circuit)

if your setpoint is acting up, that is either a reference drifting (it all based on reference), resistor divider or op amp malfunctioning.

or it might be nooise from a broken capacitor causing circuits not to settle (filter went haywire)

intermittant connector might cause things to dance around too. 14x+ magnification and a healthy dose of paranoia help find this problem

I think that really bad connector develop sensitivity to current load (resistance changes with load) and probobly temperature, which causes very minor motion due to expansion, makes it ACT up. *

*could it be a bad pin on a op amp making a very high impedance that ends up effecting the setpoint of a voltage circuit?

when your done fixing it, hook it up to a high current load (i.e. big ass resistor) and leave it on for a while to make sure it won't malfunction after 2 minutes and make danger

I have a feeling these power supplies probobly have distributed damage (lots of minor wear and tear) and that replacing stuff generally helps them. i think they basically get generally clapped out

when you screw in the pCB it gets flexed and stretched a little bit. might work when its out then stop working when you put it in. this is mechanical damage

the other thing you can do, recommended, is to reheat every solder joint on it, but it needs to be well fluxed. this means you need to do a big ass clean up after wards. I would do it for a 1kW supply though. but renember it needs to be well fluxed, and that means big cleanup. if you just do it dry to make it easy to clean it might not help things. like probobly a few hours of scrubbing to get it really nice, and you possibly loose some text and component indicators if your not careful. if you carefully apply flux, on both sides, and clean as you go, its not much worse then other penal labor

. And heat can reveal problems, so you need to grid the board and test in between doing squares if you want the most benefit and highest success rate from this method to say.. maybe identify a bad bond wire or something from heat. where it goes from intermitant to broken. if you do it all at once you can get a fix, but you won't know where.

ifonlyeverything · « **Reply #40 on:** April 14, 2024, 01:01:25 am »

You were right about something killing the regulators. I think the -15V regulator is blown (it's outputting roughly -18V instead of -15V) and the 15V regulator is running super hot because something is pulling it down to 8-9V. Auxiliary power supply output is still fine. Will dick around with this later but I'm guessing the OP07 block is screwing me over, since that's where the blown open tantalum capacitor was found.

coppercone2 · « **Reply #41 on:** April 14, 2024, 01:11:07 am »

thermal imager might come in handy here . seek thermal

or probing stuff (its fucking annoying though)

ifonlyeverything · « **Reply #42 on:** April 15, 2024, 11:56:42 pm »

Quote from: coppercone2 on April 14, 2024, 01:11:07 am

thermal imager might come in handy here . seek thermal

or probing stuff (its fucking annoying though)

Thermal camera didn't reveal anything unexpected. Only thing heating up were the linear regulators and a couple small value resistors on the 6.2V zener and the linear regulator. The zener was regulating fine. I replaced the linear regulators and powered it off my bench supply, didn't pull above like 0.05 amps at idle (due to those small value resistors.) Connected everything back up same problem with U238 being pulled down and U252 instantly shorting out. One of the output capacitors (new Nippon Chemicons from LCSC) blew the fuck up too.


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