PV Classic 30 Reverb Issue

[Perkinsman]

The reverb comes on & off. The tank is new however the reverb cord has been cut apparently to lengthen 6” possibly to accommodate the new tank. They reconnected with butte splice & screw caps which show continuity from inside the amp to the rca jacks. I first suspected the connections but after the continuity test I don’t believe the connectors are the problem, they seem to be solid albeit fugly. These PV’s have the little wire connectors on the boards & I was hoping to be able to test the reverb circuit without “unfolding” the boards....so,

What can I do to test the reverb circuit without unfolding the boards? Do I have to connect the tank while testing?

[g1]

Disconnect that molex connector at the amp end. Measure resistance at the pins where the wires are pushed in. (white to shield for each cable)

[Enzo]

Or... unplug the cables from the reverb pan, turn on the amp with the reverb up midway. Now touch the tip of each plug with your finger. One should hum. That one goes to the OUTPUT jack on the pan.

Actually, before that, just shake the amp to crash the reverb springs, does that noise come out?

Is the new pan a 4EB type, not AB?

REverbs are simple, it is either the pan, the cables, or the circuit. And in this amp, pretty much all that ever fails in the circuit is the 4558 IC.

[Perkinsman]

Ok but first, is the purpose to determine the continuity of each of the cables?..because we’ve already determined that the cables are good...Or am I measuring resistance at the amp side only? ...what’s the trick to separating thIs Molex connector? Secondly, what am I looking for as resistance on each?

[Perkinsman]

Or... unplug the cables from the reverb pan, turn on the amp with the reverb up midway. Now touch the tip of each plug with your finger. One should hum. That one goes to the OUTPUT jack on the pan.

Actually, before that, just shake the amp to crash the reverb springs, does that noise come out?

Is the new pan a 4EB type, not AB?

REverbs are simple, it is either the pan, the cables, or the circuit. And in this amp, pretty much all that ever fails in the circuit is the 4558 IC.

Thanks, I’m gonna get back to it tomorrow morning & report back. Btw, it’s an EB type & new so I’m not gonna it out. Same issue with prior tank.

[Enzo]

Never think up reasons not to check something.

If you measure right at the molex pins, you are measuring the complete circuit, down through the cable, through the pan transducer, and back. For example a good cable might not make good contact with the pan jack.

The molex connector pulls straight off the pins on the board.

[g1]

Like Enzo said, I meant for that test to check the cables & tank & connections all at once. Resistance will probably be less than 300 ohms each side (input & output ends).

[Perkinsman]

Thanks guys!