I've recently built a JCM 800, all of my plate voltages are correct. I've got -60v at bias resistors, 470vdc at the plates of my el-34's. The issue I'm having, is after I flip the stand by switch and the tubes start pulling current they don't stop pulling current. Bias starts at 0 and then goes up until the tube starts to redplate (around 300-400ma) and it keeps going til the tube self-destructs if I let it. However, I shut it off.
All of my bias components (caps, screen resistors, bias resistors, bias pot and etc read in spec and show no sign of malfunction. Adjusting the pot also makes no difference, as mentioned the bias starts and keeps going higher and higher to the point of redplating. Any one have any clue? Here's the schematic I used aswell.
Forgot to mention, this happens with any tubes. All of my voltages are 3-5% within range on the schematic.
All of my bias components (caps, screen resistors, bias resistors, bias pot and etc read in spec and show no sign of malfunction. Adjusting the pot also makes no difference, as mentioned the bias starts and keeps going higher and higher to the point of redplating. Any one have any clue? Here's the schematic I used aswell.
Forgot to mention, this happens with any tubes. All of my voltages are 3-5% within range on the schematic.