unplug it and use contact cleaner on all switches and jacks if that doesn't help take it to the Amp Doctor.

I love those amps...Like Roland Jazz Chorus w/ a mean channel

 

Thanks for the tip. It turns out I had the level down to 0 for the distortion side of the amp...thus it was "shutting off" but in reality it was switching over to distortion from clean. So it seems that it just randomly switches from clean to distortion. It occurs more when I'm playing a little louder on the clean side. The head scratcher is that when I'm on distortion, I can play as loud as I want...wtf is going on?

 

Oh, by distortion, I mean Lead channel, while clean is rhythm channel. Sorry

 

So I took it apart. Checked out some of the solder spots...turns out this amp has a life of about 10 years (check out harmony reviews on this amp and I'm not the only one having this problem). I narrowed it down, to what I thought, was the channel selector button, since this was, as I believe it to be, a simple on/off switch, I took another switch from the same amp and switched them out (one that I didn't use, I think it was the line selector for effects out or something. I don't use it, so I switched it out.)

That ended up not solving the problem. I found out that there is a power line connecting the two circuit boards in this particular amp...it's red with about 10 wires coupled into a 10 wire plug. Took out the plug, sprayed it with contact cleaner, let it dry, put it back in, but it was still acting up, much less than before but still acting up...I jostled the fourth wire (from the front of the amp) and that was indeed the source of the problem. I cut some insulated wire and bound it to this "loose" wire and now there are no problems. Had a gig yesterday and played loud as hell and no hiccups at all.

This symptom is a result of playing loud enough to cause reverberations within the amp, causing that wire mentioned above to become loose.

I am not eletrically savvy, so if anyone knows what this all means, would be more than glad to hear it...whatever I did, or didn't do, it is working now.

I hope this info helps others.
cheers

 

i have the same amp doing the same thing, and am fairly confident that i can perform the fix. What do you mean by the fourth wire? i get everything else, but the fourth wire? what do you mean? i havent cracked the amp open but if you could elaborate anymore that would be awesome. thanks for all the info so far.

 

There's an eleven-wire harness between the preamp and power amp boards. At the power amp end the 4th wire from the front (and the 5th actually) carry the channel switching voltage to the footswitch jack on the power amp board. The connectors are Molex insulation-displacement plugs and enough vibration could do exactly what he describes. You can also use a *small* screwdriver to shove the wire back into the little fork in the connector.

 

Dude!WATCH OUT! I HAD THE EXACT SAME EXPERIENCE WITH THOSE EARLY 90's CRATE SOLID STATE AMPS! Must Have Went Thru 3 Of Em' In Various Combo Configurations, Back in the Day. But, Exact Same "SWITCHING Bull, and It GETS WORSE Bro!! NEXT THING YOU'll Be Jammin' And then You'll Smell A "Very FUNNY SMELL"!! Sorta Like; SOMEONE's "Smokin' CRACK"! or Straight Plastic!? and NO SOUND!! In Any Case, These EARLY to Mid 90's SCG CRATE's SOUND GREAT!, BUT at A Bedroom, or Small Garage/Rehearsal Space Level ONLY, and As Far As Widespread Malfuncioning Problems, ITS BULL, Cause IS'NT SOLID STATE SUPPOSED To Be MORE RELIABLE!!?? Well, In The Case Of These 90's Solid State Crates,THEY "DO FAIL" UNDER STRENUOUS USE. Even Though Apocrypha's 1990 "AREA 54" & 1988 "Eyes of Time" Albums Feature This Same UNIQUE TONE, CRATE GX-130 HEAD EXTENSIVELY! All I Know,Is If Your Rehearsing with A Drummer, as I Was, These Amps Should Be Avoided!

 

i have the same amp. had the same problem. was able to bang the top or tap the face of the amp near the channel switch on the face of the amp to get it to play right.

worked for a while, but then had to tap it more and more until i really had to beat the top of it stay on the dirty channel.

long story short, i had to take it to the doctor and he fixed it for less than 60 bucks where im at in flint MI. A place called bogners sound and music.

he said it was a couple transistors that went bad and some stuff needed to be cleaned. laugh my ass off man! im glad im not im the only one that had that problem.

i know this wasnt any help, but just letting you know there are others!

 

im looking to sell my crate GX-130C by the way. but i dont know what the value is right now.

i bought the full stack used between 2000 and 2003 at $900 buckolas.

i have so many amps, gatta clear stuff out. looking to sell just the head.

anyone have a value??