Hey guys, not sure how many of you have tried to bias your RUNT 50. I just picked up a used amp, and installed some early 70's Mullard EL-34's in it. The stock bias resistor did not have high enough voltage for me to bias these tubes, and was marginal on the EH tubes that were in the amp.
I do a lot of amp work and have had to fix this issue with every 50's and 60's Fender I have worked on.
Dave Friedman was very responsive to my inquiry, he validated the bias resistor on the board.
The resistor is R59, right next to the bias pot. I jumpered a 220K 1 watt across R59, leaving the stock resistor in place, and it gave me a much wider range of bias voltages.
I have a Rev. G circuit board.
I do a lot of amp work and have had to fix this issue with every 50's and 60's Fender I have worked on.
Dave Friedman was very responsive to my inquiry, he validated the bias resistor on the board.
The resistor is R59, right next to the bias pot. I jumpered a 220K 1 watt across R59, leaving the stock resistor in place, and it gave me a much wider range of bias voltages.
I have a Rev. G circuit board.
