Wednesday, September 24, 2014


Fender Logo on Bassman

I recently repaired a Fender Bassman 10 which had let the smoke out at a rehearsal. It had been "sounding kind of shitty and not as loud" for a while. Upon inspection I found a totally destroyed high wattage resistor as well as two cooked resistors on one of the tube sockets. It seems that the 6L6 went bad and the screen grid shorted, burning the screen grid resistor and allowing excess current through the 10W power resistor. This is the first tube amp I have repaired from this era and I am no expert and the flow of events that caused this damage is not certain to me. It was obvious enough that the bad tube had caused it and simple enough to repair and test. There was evidence of previous modification and repair in there as well. I replaced the fried resistors with equivalents and tried new tubes. It worked fine!

New resistor (white rectangle).
Burned components.
Amp working with defective tube removed,
isolating the problem.
This was a "rush job" because the customer had a gig on the weekend!