Need help with my Mesa Mark V. No power on V1, V2 & V5

[nevetslab]

Weird... I can't find that one. I found an LM780. That's all.

It is the one mounted to the chassis.


I just zoomed in once scrolling in the image to get to that IC mounted to the floor. That IS the LM2940 that powers the heaters for V1, V2 & V5 preamp tubes.

[drewl]

Is this the same person from several years ago that started this thread?
FWIW, this failure is usually the four 1N4007 diodes that rectify the filament supply for DC for the heaters of the first few preamp tubes and the low voltage switching supply.