problem with Fender Champ 600

[bluesrockplayer77]

Hello all, this is my first post on the forums. Ok, so I bought a Fender Champ 600 recently and, after replacing the stock tubes with JJ power and preamp tubes, sounded great for a little practice/jam amp. However, I really wanted that saturated tube amp sound from my Champ, so I then tried something I know you're not supposed to do with tube amps. I disconnected the speaker, then ran a regular guitar cable out of the amp and into a cheap 25W solid-state amp, all this with my guitar plugged into the Champ. So, lo and behold, after 10 minutes of playing through this nasty setup, I heard a soft pop and then the back of the Champ began to smoke. I immediately unplugged the Champ, then the other amp and my guitar and waited a little bit until it stopped. I opened the back and looked around and the tubes were fine, but the output transformer looked like it blew, so I replaced the transformer with a correct replacement. I also replaced the fuse since it was blown. I turned on the amp and when I played through it I could only barely hear the guitar with the volume turned up to about 7 or 8.

Any thoughts as to the problem? I talked to a local repairman and he said it may be beyond repair. Thanks in advance for answers or comments.

[Zipslack]

You may want to peruse this thread...
http://music-electronics-forum.com/t3958/

The only one that I've repaired blew the 6V6 and took out the cathode resistor. I would start there and check resistances for opens/shorts, just because they used under-powered resistors. Also, don't overlook the possibility of bad solder/lifted traces - very common on Chinese-made Fenders.

[jmaf]

I can't begin to tell you how bad an idea that was. But you've probably figured that out by yourself by now... Having said that, there is no such thing as an amp beyond repair.

My 2 cents: If you replaced the transformer with a correct replacement, and it didn't fix the issue, maybe the new transformer wasn't correctly installed. You may be lacking G2 voltage or your cathode resistor for the 6v6 may have skewed. Try another technician, because if anyone tells you a tube amp is beyond repair, obviously they haven't ever been to this forum

[bluesrockplayer77]

I just checked for any opens or shorts, and everything seems to be ok. However, the information in the link may be just what I was looking for. It seems that guy had the same problem I'm having. I'll get some new resistors and see if I can make some headway. Thanks!

[bluesrockplayer77]

Oh yeah, it was a very dumb idea. But I knew what I was doing, and I paid the price for it =(. Anyway, I'm pretty sure the transformer was installed correctly, with specs being exactly the same and with the leads going where they're supposed to. Thanks, I'll check the cathode resistor. Yeah, every amp repair problem on this forum that I've seen so far has been resolved. Pretty amazing!

[Chuck H]

Pretty much the most expensive part you might need to replace would be the output transformer. Why any repair shop would say "beyond repair" when the most expensive part is already replaced is a clear indication that you need to find another repair shop. I'm so irritated that any "tech" would say that... Even when a fresh OT is presented to them. On any competent techs bench that amp would be working inside of fifteen or twenty minutes. Beyond repair... Pfft... There's no simpler amp than a Champ. When parts fail you replace them and then the amp works. Not that much to go wrong or troubleshoot for a tech that knows his head from a cabbage.

[g1]

You said the tubes "looked" good but have you tried another 6V6? Otherwise, as has been mentioned, check the cathode and screen resistors.

[Jag]

If you've tried a different 6V6, my money is on cathode or screen resistor!

[bluesrockplayer77]

Yes, I've tried a different 6V6 and I get the same deal. It looks like the cathode or screen resistors may very well be the problem. Chuck H, after getting all these answers for my question and also browsing the forums it seems like no faulty amp hasn't been fixed, meaning my local tech just can't work well with amps.

[Zipslack]

Repair tech?

The repair tech may have had valid reasons to tell you what he did...

1. Fender considers these amps to be "throw-away" items - they are on the do-not-repair list. When they come in, you replace it and scrap it.

2. It may not have been worth the money for the labor/parts, which means he/she may get stuck with unpaid labor.

3. Maybe the tech doesn't like/understand tubes. I had a real aversion to tube amps to begin with, but now I would rather deal with tube stuff any day (not that I'm anywhere close to being a guru)

[Chuck H]

I really do understand the "do-not-repair-list" concept, but the OP already had a new OT in the thing!?! Additional needed repair couldn't be more than a couple of components and possibly a power tube. And it would take a good tech ten minutes to diagnose it and ten minutes for the repair. So at that point, with a customer standing right at the counter, why would anyone say "beyond repair" unless they didn't feel like doing their job or didn't know how? Either reason pitches the customer under the bus without an honest reason for doing it.

[Alex R]

Well it is easier to say 'it's beyond repair' that 'I don't know how to fix it'. And a tech who doesn't know how to fix a Champ...

[jmaf]

Well it is easier to say 'it's beyond repair' that 'I don't know how to fix it'. And a tech who doesn't know how to fix a Champ...

This could easily become my signature.