With this driver board, I've heard that replacing the 2 TL072s on the driver board will restore audio. I've never run into this fault so I can't confirm that this information is accurate.
Have you run all of the pots and switches through their entire range to see if the amp will produce audio?
When amps using this board are going into protect for no apparent reason (all FETs OK), the two MMBTA42s in the center of the board are generally the cause.
Have you run all of the pots and switches through their entire range to see if the amp will produce audio?
When amps using this board are going into protect for no apparent reason (all FETs OK), the two MMBTA42s in the center of the board are generally the cause.
You should calibrate your probe. There should be a calibration test point on the front of the scope. Touch the probe to it and adjust the trimmer capacitor on the probe until the top and bottom lines of the calibration waveform are flat.
Are all of the gate waveforms (on each of the power supply FETs) the same?
The switch point seems a bit high (on the falling edge of the gate waveform) and that could be why the FETs are overheating. The ripple on the bottom of the gate waveform is making it a bit difficult to understand precisely what's happening. Can you clip the scope probe ground clip a bit closer to where the third leg of the FETs connects to the ground plane?
Are all of the gate waveforms (on each of the power supply FETs) the same?
The switch point seems a bit high (on the falling edge of the gate waveform) and that could be why the FETs are overheating. The ripple on the bottom of the gate waveform is making it a bit difficult to understand precisely what's happening. Can you clip the scope probe ground clip a bit closer to where the third leg of the FETs connects to the ground plane?
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