With no outputs installed, you can drive a strong 100Hz signal into the amp and it will show up on the output gates. That will show you if the drive circuit is working at a basic level (but won't be a good indicator of the high frequency performance). It may be possible to inject an 80kHz signal into the amp but I've never tried it.
Even with the output terminals shorted it heats up.
Here are a couple pictures of the gate signal at 40hz coming in, I see the same waveform at 100hz as well, just different timing.
Bad
Good side
Crappy pics but hopefully clear enough. I seem to be missing a frequency riding on the upper side of the bad signal. Not sure what that is about.
Here are a couple pictures of the gate signal at 40hz coming in, I see the same waveform at 100hz as well, just different timing.
Bad
An externally hosted image should be here but it was not working when we last tested it.
Good side
An externally hosted image should be here but it was not working when we last tested it.
Crappy pics but hopefully clear enough. I seem to be missing a frequency riding on the upper side of the bad signal. Not sure what that is about.
Actually, the top signal is good. The bottom has noise on it. Connect a 1000pf cap across the gate/source and the signal will become clean. The top and bottom of the waveform should be flat (or at least it should be at 100Hz). I don't know if it's your scope or the signal.
The amp produces audio, but I get this sizzling sound when I power it up. The audio output looks fine without any noise with a current limit resistor in place.
Running without a current limit it will draw huge amounts of current. The output waveforms look correct, based on section 17 of Generic Type 2.
I still think it is a cap.
Running without a current limit it will draw huge amounts of current. The output waveforms look correct, based on section 17 of Generic Type 2.
I still think it is a cap.
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