I bought this amp from ebay awhile ago, and never fully tested it. But when i appled power it have this sqealing sound? Goes away about 10s, amp powers on and plays but I noticed the fan is not working. I test the two pin on the fan input and reads about .5volts. Not enough to power the fan. No protection light also. I'm not sure if Q31 and Q34 of the fan circuit is bad? Any help would be great.
Put it back on the bench and see if you see any noise on any of the op-amps on pins 4 and 8 (for the 8 pin op-amps) when it powers up.
Also look for noise on pins 1 and 7 of the op-amps.
The voltage on all of these pins should be a straight line. Set the scope's vertical amplifier to 5v/div and set the timebase to 2mS. Set the coupling to DC.
Also look for noise on pins 1 and 7 of the op-amps.
The voltage on all of these pins should be a straight line. Set the scope's vertical amplifier to 5v/div and set the timebase to 2mS. Set the coupling to DC.
Do you have an old home stereo receiver? If so, you can use the method used in the following post:
http://www.diyaudio.com/forums/car-audio/160184-help-please.html
http://www.diyaudio.com/forums/car-audio/160184-help-please.html
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