"no_go" writes:

Hello and thank you for your answer.

The resistance looking into the secondary outputs are as follows (with
unit unpowered of course);

+3,3V Output; 0,3 ohms (no change when reversing measuring probes)

This is suspect. Check the rectifiers, caps, and anything else on
this output. Probably a dead short.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

+5V Output; 8 ohms (no change when reversing measuring probes)
+12V Output; 604 ohms (when reversing probes I get 100 ohms that rises
slowly to a few kohms)

The voltage at pin 4 of the KA7500B is 3,38 V without the green wire
connected to ground and 4,2 V with the green wire connected to ground.
I guess this indicates there are some bad secondary rectifiers in the
circuit? Should i go ahead and order some new rectifiers or are there
other things to check first?

Thanks again,
marty