View Full Version : Tubes for my Super Champ???
08-11-2009, 02:35 PM
Lately, my Super Champ has been making all sorts of ugly hum when the reverb is engaged (footswitch ON). Unless there's a shielding/grounding issue with the reverb wires to and from the tank (which I will check tonight), I'm guessing I may have a bad tube.
Based on my rudimentary electrical knowledge, and looking at the schematic at the Fender Amp Field Guide (http://www.ampwares.com/schematics/SuperChampSch.pdf), I figure a tube issue would be one of two tubes. It looks to me like both halves of the 12AT7 in V2 are used to drive the reverb. Is this correct? It also looks like one third of the oddball 6C10 in V3 (V3C, specifically) is used for reverb recovery. Is this correct too?
As long as I'm looking at tubes for this amp, I thought I'd look for some recommendations from members of the forum.
V1 12AX7 (originally 7025)
The 6C10 is hard to find, so I'll take what I can get. Curious if anyone has recommendations (maker, vendor) for the other tubes.
08-11-2009, 05:45 PM
Sylvania 5751 in v1 (less fizzy dist),
any nos 12at7 in v2 ( i use brimar just cause I have some),
for v3 get on ebay NOW and buy every 6c10 you can find, cause there isnt getting to
be more of them.
For the 6v6s either rca clearglass or raytheon. Ive had my SC for 10
years and have tried everything in it. For the reverb thing try cleaning the outside
of the rca jacks that send and return to the reverb tank. Mine have over time gotten
some crap on them that made the verb stop working.
Have a look at this
Its a circuit explaination. Damn good site too.
Give me a pm if youve anything else superchampish on your mind
08-12-2009, 10:36 AM
08-15-2009, 05:26 PM
Did a little more checking. It seems that, with the footswitch plugged into the amp, the loud hum only happens when the Reverb button is pressed on the footswitch. With the Reverb knob rolled all the way down, the hum goes away just as if the footswitch wasn't depressed. With the footswitch unplugged, the hum is there with the Reverb rolled up, but gone when the Reverb is rolled off.
Also, I hear no perceptible actual Reverb, even with the knob at 10. Just more hum.
If I unplug the Reverb tank (two jacks in the back), then the hum is gone, but there's obviously no reverb. Basically, to hear the noise, I have to have the Reverb tank plugged in, the Reverb ON and the Reverb knob turned up above 1.
FWIW, I tried changing to a different 6C10 tube (have three total in the house), but the problem seems unrelated to changing tubes. I haven't tried changing the 12AT7 tube, because I don't have a spare. I have one on order.
Anybody have any ideas on this issue?
Sounds like you might either have bad cables or a bad reverb tank. Here's some things you could check.
First, try swapping the cables where they plug into the amp. It is possible to get the input and output mixed, and it won't work well this way.
Second, remove the reverb tank (the bag should be easy to remove with two screws) and verify the cables are plugged properly into the tank connections, and the connections are tight and clean.
Then grab a pair of RCA-RCA cables from your stereo and replace the cables from the tank to amp with them. If your hum goes away, the cables in the amp are bad.
If all this fails, your tank may be defective. They aren't terribly expensive to replace though, under $20 IIRC. Try www.tubesandmore.com for a replacement. Good luck!!
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