Film-Tech Forum ARCHIVE: CP650 power supply

This is topic CP650 power supply in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Carsten Kurz (Member # 5396) on 11-08-2016, 05:32 AM:

Hi there,

has anyone ever been successful in repairing a CP650 power supply? Dolby ran out of replacements.

- Carsten

Posted by Sam D. Chavez (Member # 1841) on 11-08-2016, 09:35 AM:

Mark G has done a few but it's iffy. There are three types from different vendors and each with different wiring harness and metal sled fixture. There's a lot of glued in parts with no markings. About the only thing that can easily be tried s the caps.

I do have a small stock of the Integrated power supply bricks but none of the Lambda or the other vendor, whose brand escapes me at the moment.

Posted by Marco Giustini (Member # 4544) on 11-08-2016, 09:42 AM:

I will attempt to repair mine soon. I reckon recapping them is the first stage - especially if you don't have an ESR meter - then unfortunately it's going to be tricky as I could not find schematics. But after all they are SMPS power supplies, you may be able to find out what the issue is - especially if the PSU is dead or if it shows a permanent issue.
I did ask the question on the other forum, whether those PSU's have any weak point so maybe even though you are not an expert you could blindly replace those parts and hope for the best.

Posted by Mark Gulbrandsen (Member # 72) on 11-08-2016, 10:59 AM:

Don't waste your time with an ESR meter. Just replace them all. Doesn't take that long and average electrolytic lifespan is 7 to 12 years. There was a huge batch of these supplies that suffered from the capacitor plague and the ones leaking black crud out the top are going to be obvious. The worst aspect is that some of them have glue all over them. An exacto knife helps there.

If you don't want to fix em then send them to me and I'll fix them for you.

Mark

Posted by Marco Giustini (Member # 4544) on 11-08-2016, 02:08 PM:

I'll definitely change them all - I did not want to say that in the first place as I though you would have argued that the ESR should be checked and only bad caps should be replaced [Wink]

Is there any other known weak parts on those PSU's that may fail overtime? Mine is dropping the voltages after a few minutes - all of them. If a cap is kind of shorting the rail I guess the feedback will tell the main switching side to reduce the output for protection?

Posted by Mark Gulbrandsen (Member # 72) on 11-08-2016, 11:41 PM:

A cap with leakage could cause that. I have had the large input caps on the AC side get wonky and the supply will also act strange. I give the boards a very close visual inspection and if all looks ok then I proceede. Out of about 8 or nine boards I did I only ran into one that actually had some sort of circuit issue.

Posted by Marco Giustini (Member # 4544) on 11-09-2016, 12:52 AM:

Thanks Mark