[NeilPeart]

I'm not sure if posting about non-headphone related gear is kosher, but I'll give it a shot regardless. I have a guitar amp that keeps killing fuses. I'll turn it on and it'll blow the fuse, and I'll stick in a new fuse (of the correct specs of course) and it will repeat the process. Where can I begin to troubleshoot this issue (keep in mind I am a novice at best, as is probably evident by my lack of proper terminology, etc.)? Any help is appreciated and if this post doesn't jive with the DIY forum let me know and I'll have it moved. Thanks.

 

[Demolition]

Is it a tube amp? If so, then the most common sources of blown fuses are a dead/dying tube (particularly power tubes) or a set of mismatched tubes.

That would be one of the first things that I'd check.

D.

 

[Sewer Guy]

If this is a tube amp. 1. remove ALL of the tubes; then try it. If the fuse still blows, then it is either the power transformer, or a shorted filter capacitor.

If the fuse did not blow with the tubes removed, the problem is either the rectifier tube or an output tube. My money is on the power transformer.
Good luck.

 

[NeilPeart]

The amp is a Vox Cambridge 30, model V9320, which uses a single 12AX7 tube for the preamp section and SS for the power amp. I bought a new 12AX7 today and some new fuses and tried again. The fuse still blew. I pulled out the tube and the fuse still blew. A buddy of mine said it could be a transformer or capacitor. How should I proceed? Thanks for the input.

 

[Sewer Guy]

If you can identify the solid state rectifier; probably a fullwave bridge, disconnect wires from the power transformer from the hgh voltage rectifier. If
the fuse blows now the transformer has shorted windings; get a new transformer. If the fuse does not blow reconnect the transformer leads to the rcetifier & disconnect the wires from the output of the rectifier; if the fuse blows now it is the rectifier that is bad.

If the fuse did not blow reconnect the wires to the output of the rectifier, then disconnect the wire that goes from the output of the of the filter capacitors, to the amplifier itself. If the fuse blows now it is a shorted filter capacitor. Good luck.