14-10-2016, 03:39 PM
It's possible that an open-circuit capacitor in the lower "limb" of the NFB network could cause this. The gain would fall to unity, and depending on the phase margin, it could easily become an oscillator.
That'll be C703, perhaps - I can't read the scan. It's 100uF, 10V, just to the right of the LTP. The other channel is even less readable.
Given the age, it might be worth changing it anyway.
That'll be C703, perhaps - I can't read the scan. It's 100uF, 10V, just to the right of the LTP. The other channel is even less readable.
Given the age, it might be worth changing it anyway.
