Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Hello, I am trying to figure out an issue with a new to me rumble 500..I bought it as is hoping it is something semi simple.  It fires up and thumps powerfully when shutting it down.  No sound from speakers...faint sound from external jack into another cab.  The effects loop seems ok as i can plug into that and get sound...low volume unless I put a pedal to it.  It seemed to get a little better after I plugged headphones in and out of it.....im leaning toward input jack but any help is greatly appreciated.

Jim

It has headphone jack?  Check the cutout contact on that jack,   That is the contact that opens when a plug is inserted, it turns off the speaker.

Tried that thank you

have you tried a jumper lead from FX out to FX in?
That is another common fail point.
Phil.

I do get sound if I plug the bass into the receive side of the loop and the output jack to another speaker also works.  When I plug an instrument into the input I get very faint sound.  When I unplug from the loop in the rear its very loud.  Auxillary input works fine it seems. 

" When I unplug from the loop in the rear its very loud:

This statement is very confusing.

From what I can discern so far:
- The input jack on the front produces low sound
- The FX Return produces sound (as does the Aux In)
- The Ext Spkr jack works
(so the power amp is good)

What is not clear is what happens when you use the FX Send jack to another amplifier.
Also, have you run a patch cable from the FX Send to the FX Return jacks?

It appears that the power amplifier is good.
Until you prove out the FX Send, it is not clear whether or not you have a preamp issue or an FX jack issue.