Valvestate 8080 repair and refurbish?

Phantomboxer

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Hello fellows.
I received today a Valvestate 8080 that does turn on but no sound coming out of the speaker. Turns out that the one lead of the speaker terminals was loose... now it works. Kind of.
When turned on it sounds right IN YOUR FACE but after a while it gets a little unstable. Also there is a difference in volume between OD1 and OD2 on channel 2. But maybe that's intentional.
I checked the 12AX7 with my old tester and one triode section is almost dead, the other one is ok. Then I swapped the tube for another good one but no change in output.
Someone already mentioned that the Valvestates and JCM900s are prone to crackling pots and switches as well as input jacks.
I was thinking of doing a complete recap since the amp is already 30+ years of age.
Any other advice?
 

Jon Snell

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It is transistorised so not worth replacing probably good capacitors. They don't suffer like valve amplifiers do with heat issues causing the capacitors to dry out.
Replace the main smoothing capacitors if they are low capacity. C40 & 41 plus C61 & 62.
Fix the issues first!
Clean all pots and effects loop sockets along with speaker sockets and switch contacts.
 

PelliX

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Adding to what Jon already mentioned, the 12AX7/ECC83 is only used on one of the channels, so if your problems manifest themselves on both channels - that's not the issue at hand. The 8080 definitely has a distinct difference in volume between the channels, too - this is by design.

What do you mean exactly by "unstable"? Volume jumping up and down, signal cutting out? Especially the jacks in these models can need a bit of cleaning and love after a while.
 

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