Trouble shot a tone problem...

[massygt6]

Hi there...
I've got a clone on the bench with a strange problem...suddenly the sound has gone dark and dull on the clean channel and lost gain and cut on the od channel, becoming very "hard" and dull, seems like a wha pedal set in the middle position...
Power tubes readings looks fine and so the preamp tubes readings...there's no lack of power or volume, no popped fuses, no evidence of macroscopic problems...
I'm suspecting of a solder joint gone bad, or a shielded cable...
Every suggestion is very welcome.
Thank you
Max

[bluesfendermanblues]

Hmm, could sound like a defect preamp tube. Try replacing V1 with a tube that you know works.

If that doesnt help, perhaps you have a defect volume pot.
I experienced a lot of stupid stuff with my amp - like volume drop etc. This turned out to be a faulty volume pot (the one next to the input jack).

The 'ground' log on the pot, had lost its connection, probably due to mechanical stress from holding the grounding brass stick, across the pots.
A new pot solved the problems.

[massygt6]

Hmm, could sound like a defect preamp tube. Try replacing V1 with a tube that you know works.

If that doesnt help, perhaps you have a defect volume pot.
I experienced a lot of stupid stuff with my amp - like volume drop etc. This turned out to be a faulty volume pot (the one next to the input jack).

The 'ground' log on the pot, had lost its connection, probably due to mechanical stress from holding the grounding brass stick, across the pots.
A new pot solved the problems.

thanks Blues...very helpful suggestions, I'll try to understand if the problem is in the preamp section or in the power section using the effect loop with another amp...

[massygt6]

ok, problem fixed, the shielded cable from the input to V1 was faulty...rewired the whole thing with new cable and the amp rocks again...
just want to let you know, if a similar problem happens to someone, inspect the shiedeld cables!