I am going to start a new thread for this, since this discussion could be long and protracted. I ran into a snag trying to adjust the driver boards in my B2 rebuild. Basically, I replaced all resistors in the signal path, many fusible/fire resistant resistors, and all capacitors I had polyproylene replacements for. I also changed the big electrolytic cap with Nichicon Muse. I have unit assembled with VFETs removed. I have a 10k resistor between PG and NF and 10K again between NG and NF to simulate presence of VFETs for rough adjustments. DC balance can be set to zero with VR101, but bias remains at zero regardless of VR102. Front power meter for one installed driver board stays elevated at about 0.01W (this one has me a bit perplexed as how does signal escape FET board with no FETs installed?). I took some readings and I get the following on the first driver board: +B2=85V -B2=-85V +B=60V -B=-60V PG=15V (a tiny bit high, should be 13.5) NG=-1.3V (very low, should be -13.5) NS=0 NF=0 PS=0 On second driver board, NG measured at -45V on this one and then I quickly realized that R168 was burning up. R149 also looks charred on this second board now. I also heard a loud pop at some point. I haven’t tested transistors yet, but I’m thinking I will just replace all of TR 121, 122, 123, 124. Maybe I should just do TR 117, 118, 119, and 120 while I am at it too. Thoughts? I would also check and replace, as necessary, resistors and such as I work. I do wonder why I am having a problem in the same area of both driver boards, though. I can’t see that I have altered anything on this boards. Both driver boards seem to have a similar problem, which really has me scratching my head. I've rebuilt these driver boards before in another unit without issue. I'm also careful to measure each component I remove and measure each replacement part just to make sure it's a match. Yet, if the issue is on the driver board, it seems I made the same mistake on both driver boards. As an aside, what is the purpose of the studs that stick up and contact the TR 121, 122, 123, 124 heat sinks? They appear to just be for stabilization, but these studs look to be coupled to signal pads, which I find weird. I'd appreciate any insights as I work through this unwanted excitement.