Charvel CH-200 Amp - Cutting Out

[fredsmythson]

I have a 1992 Charvel CH-200 amp that keeps cutting out when I play it for more than five minutes.

I'll play through the amp for about five minutes and it works fine. After five minutes the amp starts to make a crackling sound and then starts to intermittently cut out.  It will then get to the point where you can barely hear the guitar through the amp.  The preamp controls do not respond.  It has the same problem when playing through either of the two channels.

I plugged the guitar directly into the effects loop and I did get a clean tone at a low/medium volume.

I've tried different guitars and cables with the amp and I'm still having the same problem.

Any ideas on where to start the troubleshooting on this problem?  Thanks!

[ilyaa]

directly into the effects loop and I did get a clean tone at a low/medium volume.

you mean into the effects return? that's you bypassing the preamp altogether and plugging directly into the power amp - was that signal intermittent? if not, sounds like your problem is definitely in the preamp! a low/medium volume tone from the power amp sounds like a properly functioning power amp. (you split the amp in half by using the effects loop - a great place to start troubleshooting it because it tells you if your problem is BEFORE the effects loop - preamp - or after - power amp)

sounds to me like you have some bad/cold/intermittent joints somewhere in the preamp - open it up and take a look - turn the amp on and poke around with something non-conductive/wooden like a chopstick in the preamp (be careful of course if you open it up!!!!!) - see if you get any crackly/weird sounds - if you do, youve found the crappy joint!

[Enzo]

Before you open it up, plug a spare cord from FX send to FX return, making a sort of bypass.   Does that bring the sound back?   FX jacks can cause exactly what you describe.


Another trick:  when the amp cuts out, ball up your fisy and whack the top of it.  Does that make the sound return?  That exposes loose connections inside.

[fredsmythson]

Thanks for everyone's help!...  I actually plugged the guitar into the "send" part of the effects loop... Ooops   :cheesy:  I tried plugging into the "return" side and it sounded a lot better with a strong medium volume.

I tried the amp again using it's standard input at the front panel, and it began to make some very strange noises.  Like it was ready to have an atomic meltdown...

I tired the simple suggestion first of plugging in a cable into the "send" and "return" inputs of the effects loop...  Wow, no more crackling and cutting out... I turned on the amp and started to play with the guitar plugged into the front panel input, and it sounded like a brand new amp.    It sounded more powerful than it ever did before, and I've owned the amp for 22 years. 

So, do the inputs on the effects loop need to be repaired or replaced?  Thanks!!!   :tu:

[Enzo]

On most amps with FX loops, plugging into the FX return will disconnect the preamp.  There are small extra contacts in the jack that carry the signal past the jack when it is NOT in use.  They open when something plug is.   Problem is when they get dirty, they no longer can reliably pass the signal along.   When you plug that cord from send to return, it bypasses those contacts.

At worst you need a new return jack, but usually a squirt of contact cleaner into the jack and then push a plug in and out a few times to rub it around, and it is cleaned.  Try that.


And so you know, it is absolutely OK to run with that cord in there.   You can do that as long as you like.

[Roly]

Hi fredsmythson, welcome.

I tired the simple suggestion first of plugging in a cable into the "send" and "return" inputs of the effects loop...  Wow, no more crackling and cutting out... I turned on the amp and started to play with the guitar plugged into the front panel input, and it sounded like a brand new amp.   

Well that pretty well nails it as a dirty bridging contact on the Send/Return sockets, a very common problem particularly for those who don't use these sockets much/at all.  Generally a drink of metho or specific contact cleaner such as Deoxit plus a bit of exercise/scrubbing as Enzo suggests should clear it up, but you may have to give it a "doing" two or three times to get it fully right.  If it doesn't come good after two or three cleans, or is only a partial cure, then replacing the offending socket is normally a pretty simple job and should see it well and truly fixed, but try just cleaning it first and let us know how you get on.   :tu: