Universal Audio 2192 PSU

[Coop]

Hello,

A couple of years ago I bought a Universal Audio 2192 as my Master Clock and 2 Channel Converter for my mixbus. Recently the PSU of this unit died. Unfortunately Universal Audio discontinued the product a long time ago and they don't sell any replacement PSUs anymore. So I thought I could maybe repair it myself. Found a MOSFET that had a short and 2 resistors that where blown as well. Replaced the parts and turned it on again. No smoke appeared, the fuse didn't blow, but the PSU is not working. No voltage at the output side. Did some testing and I think I narrowed it down to the transformer. Did a little Google search but unfortunately I couldn't find any information on the transformer.

Does anyone have more information on this PSU? Or should I just try to get either an off the shelf PSU to replace the faulty one, or modify one to get the proper voltages (+36V, -36V and +8V)?

Best wishes,
Johnny

 

[Khron]

A chunk of wire is VERY unlikely to have failed, especially if there's no traces of overheating or anything.

MUCH more likely is that, when it kicked the bucket, the MOSFET also took down the PWM controller that was driving it. And/or that transistor that's next to it. Can't really read the markings on that 8-pin chip; likely some UC384x or clone thereof(?).

Can't really help wondering how exactly you determined the transformer to be the culprit, though...

And which resistors were burnt?

 

[Coop]

I know that it is very unlikely for the transformer to fail. I did measure on the secondary side and got only 2V or so and I had a shorts between ground and almost every point on the side where the LM317 sits. Checked everything there and it measured fine. Once I removed the transformer, the shorts where gone.

PWM is a UC3842BN and the transistor a MPS 3906. Will replace those too and see if it changes the state of the PSU.

R11 and the one left to it were burnt.

 

[Khron]

I had a shorts between ground and almost every point on the side where the LM317 sits.

... Because the transformer secondaries are NOT a couple of turns of wire that basically measure as a dead short, right?

Checked everything there and it measured fine.

Rectifier diodes on the secondary measure good too? And which output did you measure 2v on?

That PSU must have at least two outputs, i see two TO220-packaged (double) diodes; the LM317 is designated U58, I'm assuming?

R11 and the one left to it were burnt.

Those two resistors are both connected to the MOSFET source pin? The chunky one likely the current shunt, and R11 in series with the current sense pin of the 3842. That one is most definitely toast, and should be replaced before any further testing (that would only lead you down a rabbit-hole of false assumptions).

 

[jvancorduroy]

Hello,

A couple of years ago I bought a Universal Audio 2192 as my Master Clock and 2 Channel Converter for my mixbus. Recently the PSU of this unit died. Unfortunately Universal Audio discontinued the product a long time ago and they don't sell any replacement PSUs anymore. So I thought I could maybe repair it myself. Found a MOSFET that had a short and 2 resistors that where blown as well. Replaced the parts and turned it on again. No smoke appeared, the fuse didn't blow, but the PSU is not working. No voltage at the output side. Did some testing and I think I narrowed it down to the transformer. Did a little Google search but unfortunately I couldn't find any information on the transformer.

Does anyone have more information on this PSU? Or should I just try to get either an off the shelf PSU to replace the faulty one, or modify one to get the proper voltages (+36V, -36V and +8V)?

Best wishes,
Johnny

Im experiencing the same issue with this Powdec CMI-103X-A, still blowing fuses.
Any suggestions on a Replacement PSU or any information on proper voltages of 6 pin CN2

 

[Khron]

Im experiencing the same issue with this Powdec CMI-103X-A, still blowing fuses.
Any suggestions on a Replacement PSU or any information on proper voltages of 6 pin CN2

If it's blowing (mains) fuses, your problem is on the primary side.

 

[Brian Roth]

If it's blowing (mains) fuses, your problem is on the primary side.

Could also be a bad rectifier diode and/or filter cap on the secondary side.

Bri

 

[Khron]

Could also be a bad rectifier diode and/or filter cap on the secondary side.

Bri

Causing the psu not to start / be stuck in some hiccup mode, sure. But blowing mains fuses?

 

[Brian Roth]

Good point. Look for Rifa caps on the primary <g>?

Bri

I fixed my typo!

 

[Khron]

Rifa Evox Rifa PME are the infamous ones...