Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Hi, I'm working on a friend's Marshall Valvestate 8040, it is stock, clean, no fiddling, no dust, just scratchy pots. Power supply is steady, no DC on the pots, no leaking coupling caps.

Using quite a bit of contact cleaner. Amp works a lot better now after cleaning the pots, BUT, wondering if these are the "economic" pots that have cardboard backing and will need to be replaced if they go intermitant over a few days?

The amp is over 30yrs old I told my friend it would be a good idea to replace the electrolitycs. Making a PL for him, he said if the cost goes too high he'll sell or scrap  it.

Schematic: https://www.drtube.com/schematics/marshall/8040-iss8.pdf