Is the resistance between R2/R3 and D1 still “zero” after you have reinstalled C3? If so, as suggested by Evan, please check if there is any solder bridge/whisker. Please check both sides of the PCB. A whisker can be very thin.
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There should not be a short there. If no bridge/whisker, then (1) either R2 and or R3, and (2) BS170 at Q6 need to fail as short circuit to create that status, I think. Is the resistance from R2/R3 to GND about 21.0 ohms?
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Hi Evan,
Thank you for stepping in. I really appreciate it. This gentleman’s amp worked fine one day (25W at 14V), but no output the next. His troubleshooting found incorrect voltages at L10, R13, the first step after checking of supply and 5V regulator voltages in the NA5Y’s video. We traced it to abnormal resistance at C3 and are stuck there now.
