I just bought a non-working P-100 but it looks different than the one in this thread. I think mine must be an earlier version.
The amp has a bias issue on one channel. The amp has a board with pots to adjust the tube bias (see right side of picture below). I believe the board connects to the cathode and then there is a 10 ohm resistor to ground. When I first powered up the amp with full voltage both of the 10 ohm resistors on the bad channel burned out. I thought the problem could be a bad cap in the bias board. Today I replaced the caps and the burnt resistors. I powered the amp up and thought I solved the problem. I had the amp on for about 10 minutes and began adjusting the bias to the .5 volts dc documented on the bias board. When I connected my multimeter to the output side tube on the bad channel I noticed the voltage begin to rise. Before I knew what happened the 10 ohm resistor flashed and it was gone. Any suggestions what to try now? I have tested the tubes and they all test good.
The amp has a bias issue on one channel. The amp has a board with pots to adjust the tube bias (see right side of picture below). I believe the board connects to the cathode and then there is a 10 ohm resistor to ground. When I first powered up the amp with full voltage both of the 10 ohm resistors on the bad channel burned out. I thought the problem could be a bad cap in the bias board. Today I replaced the caps and the burnt resistors. I powered the amp up and thought I solved the problem. I had the amp on for about 10 minutes and began adjusting the bias to the .5 volts dc documented on the bias board. When I connected my multimeter to the output side tube on the bad channel I noticed the voltage begin to rise. Before I knew what happened the 10 ohm resistor flashed and it was gone. Any suggestions what to try now? I have tested the tubes and they all test good.
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