Back in June I received a Peavey JSX head. The owner said the fuse had blown And that he saw a flash and expected a bad tube and screen grid resistor. I created a thread back then: https://www.tdpri.com/threads/peavy-jsx-head-r77.1073134/ ...trying to understand this complex amp. Upon further investigation, I found that a few resistors had blown (R77, R121, R122) Which are elevated heater supply, and artificial center tap resistors respectively. Also, the trace going to the plate of V6 exploded likely shorting to pin 2. I replaced all these along with new screen grid resistors... and a couple diodes and caps that received collateral damage and the amp got new power tubes and I biased it. I made a jumper to replace the exploded trace. It sounded great and worked fine for about 3 months. Now, the guy brought it back to me, I opened it up and everything looks exactly the same as last time. R77, R121, R122 burned up. I replaced them all again as well as cleaned up everything around them, I installed a new tube socket (V6) due to it getting caked in suit twice. I powered it up with no power tubes through the lightbulb limiter, light dims properly. Voltages looked ok. I installed new tubes (all 8) and powered up through the lightbulb limiter. As soon as the tubes got warm, V6 started to flash... I haven't had a chance to do anything else since then, but I just learned that the owner had the speaker cab wired improperly. So who knows what impedance the OT saw... could that be the issue? I checked dc resistance and for continuity through the primaries and secondaries, which looked fine. Im going to recheck voltage going to the EL34's (without tubes) again when I get home. What else could I check? Any ideas. Since I havent been able to bias the new tubes, could there be too high voltage due to the bias being too low causing the tube to flash?