I hav a 70’s model peavey 400 amp. Supposedly it sat in my customer’s Dad’s closet for years. It was working. He took it out and it tarted blowing fuses. So he tried to fix it himself. He bought power transistors, and replaced the burned resistors. But there is sill too much current. I put about 30 vac in and the curret was up to 2A already. I have checked every transistor nd they all check good with the dmm.
I measured bout 2 or 3 volts on the output with 16vac going in. So something is wong.
But this evening I was looking at the IC’s for damage, ad Icouldn’t find U3? I kept looking and discovred it’s not there at all? It’snot like it is an optional circuit because all tgeassociated resistors are there. It is a 4558 opamp that measures the voltage across soe 0.1 ohm resistors at the center rail. I guess it is an idle curren adjustmnt circuit? Not he kind of thing that the amp wouldwork without?
Anybbdy seen these amps with missing parts on purpose? I think my customer’s story is a bit flawed.
I measured bout 2 or 3 volts on the output with 16vac going in. So something is wong.
But this evening I was looking at the IC’s for damage, ad Icouldn’t find U3? I kept looking and discovred it’s not there at all? It’snot like it is an optional circuit because all tgeassociated resistors are there. It is a 4558 opamp that measures the voltage across soe 0.1 ohm resistors at the center rail. I guess it is an idle curren adjustmnt circuit? Not he kind of thing that the amp wouldwork without?
Anybbdy seen these amps with missing parts on purpose? I think my customer’s story is a bit flawed.
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