Strange amp problem

[blackreverend]

Hi All,
I have a old Genz Benz combo amp, and lately I've been having a problem where the sound randomly cuts out or fades to very soft; I've found that whacking the strings brings the output back to full.

Any ideas?

[AwkwardLoudness]

It's probably a loose solder connection somewhere inside the amp.

Dirty jacks can sometimes cause issues like this. Clean out all of the jacks with Deoxit: input, outputs, effects loop jacks (if any).

[Christov]

I repaired a Peavey Combo 300 with the same problem. There was an inductor coil on the circuit board that had broken. It worked when it was making 'connection' but not when it didn't. As others have said, I would check for cold solder joints. Pull the board and retouch the connections to make sure they are all fine. Good luck.

[Dgoy]

Hey I got the same problem but I checked everything. I don't know what my brother has done with it but while I was playing some spider he kinda broke it.

[agedhorse]

First thing to check is the effects return jack. Most common issue in every amp by every manufacturer that uses a serial (series) effects loop. Cycle it a few times and if the problem disappears you are done. Generally this nis the only thingthat needs to be done.

Don't go pulling PCBs and tearing the amp apart. It's not user serviceable and if you don't know what you are doing you could get hurt or damage the amp beyond repair.

We still support all of our past products if you find that you still need service after checking the effects loop.

[blackreverend]

sorry, but my amp smarts are limited; what do you mean cycle? Is that like blast deoxit? or turning the knob a lot?

btw, the model is the GBE series 1 with the 12' and horn.

And thanks!!

[agedhorse]

Just plug a 1/4" plug into the jack a couple of times.

We still service that combo if that's what it comes down to.

[craig.p]

Originally Posted by blackreverend

[...] I've found that whacking the strings brings the output back to full.

What leads you to believe it's the amp and not the instrument? Just wondering. Or did I miss something?

[blackreverend]

because the problem only occurs when i am playing through this amp.

[fdeck]

+1 on cycling the effects return jack. Or, running a spare cable from the effects send to the effects return.

Another thing that can go wrong on some amps is that stress on the input jack eventually causes solder joints to break. This is a good reason for always running your input cable through one of your speaker handles.

[blackreverend]

BTW, does it matter if the amp is on or off when you do this?

[BassmanPaul]

Best done with the amp off. Less noises that way.

[blackreverend]

OK, so here's an update
-I did the cycling thing on both the effects input and output, sprayed deoxit into it and (very stupidly) loaded it into the car for the gig tonight - well, now there is NO sound whatsoever; it is the amp because i broke out a buddy's amp who also played at this venue, and it worked perfectly.

So what would the next step be?

[BassmanPaul]

Still try linking the send and return jacks with a signal cable to see if they're the problem.

[blackreverend]

ok, ill try that, thanks

[rodl2005]

then try - if U need- plugging ur bass in to the FX return.

If you've got a pre amp/pedal to run before this it'll help, but you SHOULD hear SOME sound IF it's working when bass is plugged directly in the the FX return

[GrowlerBox]

Whatever you find, I suspect it might be time to take agedhorse up on his service offer.

[jelwood]

Had this exact problem with my amp, sound would fade out but if I turned up the volume and gave the strings a good smack the sound would come back. Well after cleaning all the jacks, checking for a bad solder, everything, I finally found that just by chance, as I was poking around with a pencil eraser, that I had a relay with bad internal connections. But I suppose it could have been anything, not just the relay. I do wish you the best of luck, I know how frustrating it can be.

[calebbarton]

Originally Posted by agedhorse

First thing to check is the effects return jack. Most common issue in every amp by every manufacturer that uses a serial (series) effects loop. Cycle it a few times and if the problem disappears you are done. Generally this nis the only thingthat needs to be done.

Don't go pulling PCBs and tearing the amp apart. It's not user serviceable and if you don't know what you are doing you could get hurt or damage the amp beyond repair.

We still support all of our past products if you find that you still need service after checking the effects loop.

+1,

This is really common. Try this first.

[blackreverend]

so just out of curiosity, if i find that it is a problem with the effects loop, is there a way to just disconnect it since i never use it?