Ampeg SVT4-PRO troubleshooting (thanks Enzo)

[jeffsw6]

I am troubleshooting an Ampeg SVT4-PRO amp I just bought second-hand from a local guy. It worked fine at his house, but after a short car ride home and a week of sitting in my garage, it "doesn't power on." No LED or fan activity, etc. I am guessing something got shook loose by the car trip.

I found this thread where Enzo posts the schematics http://music-electronics-forum.com/t15870/

I started taking it apart. What a nightmare it must be to work on these things. I thought by purchasing a mid-range Ampeg bass head I would have something that is easy to maintain, but it looks like it is going to be a time sink.

I am not very far into it yet, but with my VOM, I get no continuity from the IEC connector neutral prong to J14 or J21 on the AC input PCB. J14 is wired to the convenience receptacle and J21 to the primary side of the big transformer. I think there must be a bad solder connection on the under side of this PCB where the IEC connector's neutral should be connecting to the board (to J14 and J21.) Sounds sane?

I checked the power switch and circuit breaker, as well as the easily-accessible fuses. I did not dig into the ones under the transformer yet, but it looks like I might have to remove a lot of components to get at the bottom of the AC input PCB.

[jeffsw6]

In case anyone is curious, the problem did end up being failed solder from the AC input receptacle to the PCB. Added new solder to the underside of it and the amplifier now works correctly. Thanks again, Enzo, for that thread with the schematic. I would have spent a lot of money on having it repaired by a shop if I did not have access to those drawings!