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Jeroni Paul Jeroni Paul is offline
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Default Help for hard repair attempt

Eremita Analogico wrote:
Hi, preliminary tests was done some times ago, and if I remember right,
the various supply lines do not have ripples. When I got time, I will
try again to verify supplies.
The tooths are stationary over the waveform.



These tooths look pretty clean and perfect to come from a failing capacitor.
If this scope has a probe calibration signal or output maybe some signal is leaking into the input. Or some other source is leaking in the signal path. Some hints can be obtained observing how it changes with amplitude adjustments and scan timings.
I would start scoping the input with nothing connected to it to check if that square signal is there and if possible trace thst input through its stages.