DWM3640 distortion at input

NadaD

Member
2017-10-30 7:30 pm
Got amplifier which were repaired unsuccessfully before.
What is done:
* got +/- rails working
* no output fets installed
* output driver card is installed in header pins for easier troubleshoot
* no low side gate drive switching for outputs when signal is driven in
* +15 and +/-5V at output driver card are present


I checked signal when driver card is out of the board and got great looking signal.
But right after i put back output driver card, the same spot (driver card input pin) where signal was good, now looks like in picture.
Does someone have hint where to look, what cause this issue only when output card is installed?
 

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