Juno 106 Faulty CPU (DA conversion)?

Hi everyone

I need some help to restore a Juno 106… it switches on fine, The preset sounds are working properly, the chorus works, and all keys are fine.

However, when I enter to the writing mode, I always hear the same static sound, and whatever I do on the panel board, nothing changes.

I already cleaned all faders on the board, and my Microprocessor on the CPU seems to receive the right input on the AN.
I had really bad signal shape between the microprocessor and the EPROMs on both (module & cpu) boards. I took out both EPROMs and now my signals are ok.

I was wondering if this could have been the origin for the faulty D/A conversion ?

If anybody could help me, I don’t really know where to look now, I am beginner, but I try my best to learn.