The Amp Garage

Range on bias pot is -36 to -46 mv.

Initial readings were ma via my bias probe. Last reading is in mv on pin 5.

With tubes installed...510 plate voltage and -43.9 neg bias on pin 5.

I was at -60 to -90 before I changed the screens. Now I'm over -200, off the 200ma scale. I think I'm gonna change the 47k bias resistor to 56k to calm it down a bit.

Hey guys, I have a 1973 MKII S/L on the bench with some wacky bias going on. I retubed it with KT77's (which was in it previously). When the amp came in it was at 60ma bias, too hot. Checked the original screen resistors and of course they were drifted way off spec. Replaced with all new 1K 5W 1% an...