[rescue] SUN IPC PSU - still not working after recap

[Jan Liška]

Hello everyone, and thank you all for your helpful responses.

I’ve finally managed to repair the PSU. I desoldered all the major components and discovered capacitor fluid underneath the main transformer — an area that couldn’t be properly cleaned from the sides. This fluid likely caused a short circuit, triggering the immediate shutdown.

I thoroughly rinsed the board with soapy water and cleaned the fluid from all components. After reassembling everything, it now works perfectly.

Best regards,

Jan


From: Jan Liška <liska at peterkapartners.cz>
Date: Friday 6 June 2025 at 14:42
To: "rescue at sunhelp.org" <rescue at sunhelp.org>
Subject: SUN IPC PSU - still not working after recap

Hello,

I’ve started recapping my IPCs using locally sourced low-ESR capacitors. However, both PSUs I’ve recapped so far exhibit the same issue:

They power on for a very brief moment (about 0.1 seconds), the 5V rail voltage rises to 2–3V, and then the unit shuts down. I checked the units for cold solder joints and significant corrosion damage on trails but found none.

I’ve been advised that either one of the TLP634 optocouplers may be faulty, or the capacitors I used might not be truly low-ESR as claimed by the seller.

I doublechecked the capacitors and they seem to be OK - I used mostly Panasonic low-ESR capacitors like CE 3300uF 16V EEUFR1C332L. I replaced all capacitors except for the largest 400V one.

Before I proceed with replacing more components, I would greatly appreciate any advice.

Thank you!

Jan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sunhelp.org/pipermail/rescue_sunhelp.org/attachments/20250622/a3e9b4fa/attachment.html>