Old silverface Bassman from 1970. One power tube was totally burnt out. The amp was nearly all original other than a few modern tubes. It was in need of a recap and some various other maintenance.
Old bulgy, leakey Mallory caps in the power supply needed to go. They are original and are still kinda working after about 45 years! The 4th from the left is visibly oozing it’s electrolyte (an ionic conducting liquid)!
Looking from left to right you can see the 4th and 5th cap have 235-7018A and 235-7015A (it looks like) printed on the paper covering, indicating they were manufactured during the 15th and 18th weeks of 1970.
Nice F&T replacements for strength and stability in this modern era.
Looking down the chassis. Various cathode bypass capacitors were replaced as well as the 470 ohm screen grid resistors. One measured 390 ohms and the other was 712 ohms.
There is a bias trimpot attached to the hum balance pot installed by some previous tech visible just to the left of the upside down “70” written on the chassis.
Fender Bassman AB165 schematic
IRATION AUDIO 
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