Repair of a Rohde & Schwarz power supply

[Supsnoopy66]

Hi all!

I got myself a used Rohde Schwarz FSEA.
The unit shuts down after 5 seconds indicating a PSU issue. I manage to force a startup but it appears that the 5.5V supply is only at around 2.5V. I tried removing modules but it doesn’t change.
I therefore suspect that the psu is the culprit here.

I was wondering:

- Does anyone happen to have a schematic for the Ascom psu used by R&S in that generation of instruments? It’s quite packed in there but nothing obviously wrong at first glance

- Did anyone face a similar issue? I found an evidence of a bad smd cap on the forum but mines seem ok so far.

Thanks a lot for your help!

Best,

[fzabkar]

I would spend the time to draw up a diagram for the "mid board".

https://www.onsemi.com/pub/Collateral/UC3844-D.PDF