71 Fender Champ problem

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71 Fender Champ problem

Postby Praisepunks on Wed Apr 20, 2016 9:34 pm

Hello all,

I began to have the following problems with my 71 silver face champ after playing my amp at high volumes for about 10 minutes.

Amp produces no guitar sounds, though a noise floor and some electronic crackling are audible, the crackling mostly just right when it powers us. The 5Y3GT is also glowing VERY bright at all times. Fuse is not blown, and I've opened the amp up and not seen any bad looking resistors or components inside. Admittedly, I may be bad at identifying something like that.
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Re: 71 Fender Champ problem

Postby keithb7 on Tue Apr 26, 2016 1:58 pm

I would recommend you start with some simple stuff like swapping in some known good tubes.
Confirm guitar signal is working properly in another amp. Speaker wire connections all look good?
If you are not comfortable around high voltages inside the amp, then I recommend taking it in
to an amp tech.
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Re: 71 Fender Champ problem

Postby stratele52 on Tue Apr 26, 2016 2:27 pm

Check if you have the right fuse, my old amp user put a too powerfull fuse.
Keep 5Y3 in the amp and remove all other tubes ; how 5Y3 look ? Less bright or no ? Crackling ?
Less bright ; put 12XX7 tubes only , test 5Y3
6V6 output tube may have a too hot bias or you may need a good one .
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Re: 71 Fender Champ problem

Postby Dean Jr. on Tue Apr 26, 2016 8:11 pm

Tech time, imho. Problems do not always manifest themselves visually. but the sonic failure is enough to know that someone has to check the circuit. IF the amp has never been recapped, expect that to be questioned.
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Re: 71 Fender Champ problem

Postby stratele52 on Tue Apr 26, 2016 9:35 pm

I don't want to argue with you but new filter caps won't fix this issue.
Bad filter caps do hum all the time even with volume to off.
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Re: 71 Fender Champ problem

Postby Dean Jr. on Tue Apr 26, 2016 10:33 pm

NO argument here......facts.....
I have had filter caps fail like this without exhibiting a hum. Long before filter caps start humming, they are weak. The sonics suffer, and odd things go on. And.....I didn't say that the filter caps were the problem. I said...'expect that to be questioned."
I agree that the fuse needs to be checked and that tubes are suspect. But....imho, it is tech time for this amp....even if a 12AXy and/or a 6V6 cure the immediate problem. YMMV....
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Re: 71 Fender Champ problem

Postby dkevin on Fri Sep 16, 2016 2:43 pm

I have a Silverface Champ that behaved much the same as your amp. It would warm up and play nicely but as it got warm, it would crackle and lose sound. I finally took it apart and looked closely at all the connections. I suspected a faulty solder joint that was thermal...as it heated up the joint would become intermittent. What I discovered was the plate of my 6V6 (pin 3) was never soldered but simply wrapped around the tube pin as if it was awaiting solder. It is posssible the amp left the factory like that and was considered ok because it would perform fine for at least the first 10 minutes or so. The tube pin showed no evidence of ever being soldered, nor did the wire. After I soldered it, the amp performed...well...like a Champ!
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