Just to be clear on something, where is your ground lead when you’re taking your DC output measurements?
When I measure the DC outputs, I use one of the analog grounds (pin 5/6 on CN1) to measure. For CN2 I use 3/4, but I’ve also used 5/6 before to test).
Just a final update on this, it turned out to be a faulty M5230L IC.
After I replaced it the outputs on CN1 and CN2 are showing correct voltages now (+15 and -15V).
A big thanks to everybody who contributed to this topic 
Those M5230L IC’s are hard to find and I wasn’t able to find a substitute, so I guess I got lucky and power supply board is healthy again (I also replaced the rectifiers)
The unfortunate part, my issue in this topic is still present. I worked on the power supply board first just to eliminate that being the culprit.
hey where did you place that fan, I have an eps and want to keep it cooler. at the moment when ever I turn it on I prop up the front panel a bit to let it circulate. but where to place a fan I wasn’t too sure where the best place for it. there isnt much room any close to the PS.
The JX-8P synthesizer is experiencing issues related to power supply stability, potentially stemming from aging or faulty components, including the 25V 4700uF capacitors. These capacitors play a critical role in filtering and regulating voltage within the power supply unit.