I just ordered some parts and will update you as soon as they arrive. The NJM2369 is actually pretty hard to buy and the delivery time is about 14 days. The waffle plate measured out fine. Also after removing the plate the current draw stayed exactly the same, so I do not think that the plate is inv...

I have to thank you for your time and patience! I think I desoldered all external components and tested them one by one at this time, including IC702 and I renewed the solder joints of T302. I also desoldered C841 and measured 150uF across all frequencies. For further reference, desoldering C841 wor...

Also here are some measurements between Drain and Source of the FET when turning on the power:

That is the output pin, when it is running: https://i.imgur.com/d6OE9eQ.png https://i.imgur.com/SmOphaG.png And thats the output directly after shorting pin 1 and 2 with a resistor: https://i.imgur.com/bMg3Z0m.png When it is running it is definitely switching the FET.

When turning on the power, FB looks like this:




And the output like this:

C843 and C844 are now both new but the problem is still the same. Feedback when it is running: https://i.imgur.com/CW7I9jL.png https://i.imgur.com/EU6jPMF.png CS is at 1V but got some noise on it, I tried to capture it with AC coupling: https://i.imgur.com/aPBGmvP.png

I get 0.016 Ohms between pin 1 and 3 (4 wire measurement) and I think I even traced it out a few days ago, they are both connected to GND. So I can only connect the resistor between pin 2 and GND and it starts after removing the resistor. I also just replaced C844 with a new one from a good brand, b...

The 4.7k resistor works but something like 10k seems to be to high. So the 4.7k resistor is the highest value this reliably is working. When I short pin 1 and 2 absolutely nothing happens, the board starts working after removing the resistor and stays in this state. At the time the board was magical...

Thank you so much for your effort and great details about IC702! I will try out your suggestions today and add further information to this post. One thing that is strange is that shorting pin 1 and pin 2 with a 4.7k resistor actually makes IC702 switching again. Something has to go wrong when poweri...

@coulomb TR310 is fine. I desoldered the MOSFET and tested it in a test circuit and it is switching normally. @kiev I just double checked the voltage divider and my measurements and solder joints are okay. I resoldered the 220k resistor and removed the 330k one. Even after removing the 330k resistor...