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Hello, ive got a 1970's vox ac30 solid state amp and its sounds great except the vibtrem does not work, any ideas to fix it, thanks ade

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You can get a circuit for your amp from here.

Not sure what you electronics ability is, but if I were repairing the amp, I would look to check that there is audio getting through the opamp stage 1C, then the function of the FET 2N3819 to provide the vibrato effect. It has an oscillator driving its gate, that too should be checked for operation. I know it is not a "do this to fix it" repair, but without being able to do these checks with an oscilloscope on the amp, nobody can say for sure what the problem is. If you have any questions, I am happy to talk to you about the amp. Good Luck with the repairs.


Posted on Nov 08, 2008

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