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Author Topic: The amp has hit the fan
Thecoslar

Posts: 45
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Post The amp has hit the fan
on: August 21, 2012, 18:37
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So I was playing through my Fender Champ 600 (all stock), and suddenly I hear this awful humming sound, my guitar signal stops going through, and I smell- and see- smoke. Naturally I turned it off, let it cool, and then came back to take a look. I can't tell what the hell happened. The tubes appear to be fine, nothing is obviously charred or damaged, and the speaker is undamaged. I turned it on to see if it'd work, and as soon as I hit the switch I got the humming sound. No time for the tubes to warm up, so it's not them. I have no idea. The humming sound is not controlled by the volume knob at all. Since the hum happens without the tubes warming up, and the guitar signal doesn't reach the amp, it's got to be pretty early in the circuit, right? It happened while I was playing chords on a new pedal (the Fulltone Catalyst, which kicks lots of ass. It sits halfway between an old Russian Muff and a clean boost). The output was no higher than anything I've done before on the amp, though I've only had it for a week and a half. It's under warrantee, so it'll get fixed,I just want to know what happened, why it happened, and if it was my fault.

mwseniff

Posts: 149
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Post Re: The amp has hit the fan
on: August 22, 2012, 05:14
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It is probably not anything you did, you can't damage it with a FX pedal unless you beat on the amp with the pedal... The fact that it didn't blow the fuse and shut off is curious to me. It may be something in the filtering of the power supply but that is a wild guess based on nothing but your description. It could be as simple as a bad solder connection on the pc board but take it to a Fender service representative ASAP. Do not run it anymore as it may cause more damage. The fact that no guitar signal gets thru doesn't really mean it is early on just that the problem is before the spkr. Do not open it up if you have no electronic chops there is enough voltage inside to knock you on your rear end (assuming it doesn't kill you). The fact it happens immediately without warm up doesn't mean the tubes are all good the output tube could have shorted internally and that would certainly match your symptoms. In any case if it is only a week and a half of use even the tubes should be covered by Fender warranty. Once this is repaired it should give you good service since they will replace the one bad part that caused the problem, after that the odds against you having another failure become exceedingly small.

smgear

Posts: 170
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Post Re: The amp has hit the fan
on: August 22, 2012, 06:03
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+1 mwseniff. I'm certainly not an expert, but the smoke could signify a shot filter capacitor which could have trashed other circuits down the line. It's rare in newer equipment, but not unheard of. Don't fire it up again and get it serviced.

Jeff_H

Posts: 47
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Post Re: The amp has hit the fan
on: August 22, 2012, 06:37
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Agreed that you couldn't have killed it with an FX pedal. Some amps (don't know about the champ) can't take operating anywhere close to full-out without endangering their output tubes. Also, there is a know effect called "infant mortality" for electronics parts. Some small percentage of parts fail within the first little bit of their operating life - it can't be helped. This is probably what happened to one of the many components in your amp.

A qualified service person can tell you what happened and hopefully why.

Thecoslar

Posts: 45
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Post Re: The amp has hit the fan
on: August 22, 2012, 09:04
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I'm taking it in for repairs next week. I don't have any real electronics experience, so I'm not planning on poking around. I appreciate the help guys, it was sort of terrifying to see smoke coming out of my new toy.

Digital-
Larry

Posts: 192
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Post Re: The amp has hit the fan
on: August 22, 2012, 16:38
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In the electronics world, all components are filled with "magic smoke" and it is very bad to let it out.

Once I designed a circuit with some CMOS chips in it and turned it on to test it. It wasn't working and while I didn't see any smoke, something did smell hot. Thought I'd check around by putting my finger on various chips. Did you know that there's a little time delay between when you put your finger on something really *(&(*@#$ hot and your brain actually noticing this? I wound up with a nice rectangular blister on my finger GAHHH!!!!!

Good luck getting your amp fixed!

Thecoslar

Posts: 45
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Post Re: The amp has hit the fan
on: August 22, 2012, 18:43
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Heh. I'm a blacksmith. I know all about the magical "*(&(*@#$ hot delay". I brought it in this evening (I got antsy) and they said that the tubes were improperly biased at the factory, and this caused (insert part name that I already forgot) to overload or something like that. So, they're replacing the tubes and the damaged part, everything should be good in time for my gig on Saturday. Hopefully.

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