Cross-post from TDPRI. I built an Encore a year ago, and it's been working well, until a month ago when it developed an intermittent problem with the power supply... maybe? I normally run 6L6/5AR4, but I swapped those out thinking maybe they were damaged. Either causing the problem, or victims. Victims, turns out, because the problem persists with the 6V6/5U4GB configuration I'm running now. Yesterday, I had it on the bench, the tubes were nicely biased to 24mv, and the amp was behaving itself. I turned the amp completely off, and had lunch. Then, I came back, turned the amp on, waited, then switched it off standby. Bingo. I had the meter on the bias points. Both tubes read around 180-200mv. I had a guitar already plugged in, and confirmed I had sound -- one quiet strum, sounded okay. The tubes started to red plate, so I switched to standby. When I did that, I saw a big flash inside the rectifier. Upon inspection, the rectifier has tiny flakes of what look like glass loose inside. This same thing happened with the 6L6/5AR4 setup, except I wasn't watching it so closely when it happened. At this point I'm assuming the rectifier is damaged, and the tubes to some degree as well. Can someone point me in the right direction? If you're not familiar with the Encore, in many ways it's very similar to AB763. If you want to describe it in those terms, I can probably translate any differences. I'm still learning. If you say something like "bias supply", I'll need to ask where that is on the schematic. Thanks.