Fender Supersonic 22 Hum

Linkslover

Tele-Meister
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Mar 16, 2017
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Naples, FL
I've got a Supersonic 22 with the original 4-button foot switch. When I have the reverb clicked on, there is a background hum that is noticeable when I'm not playing. If I turn the reverb off, the hum goes away.

I'm wondering if anyone else has this same problem and if anyone can tell me how to fix this.

Thanks,

LL
 

dan40

Friend of Leo's
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Aug 19, 2015
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Richmond Va
I have no idea which tube to check. What cables are you talking about


If I was looking at the correct schematic, it looks like v3 drives the reverb and v4 is the recovery stage. If you have the correct tubes on hand, I would try swapping those one at a time to see if there is any change. For the reverb cables, there should be a pair of rca cables that plug into the back of the amp's chassis and lead down to the reverb tank. You try unplugging and reinserting them several times to help clean the contacts. Make sure you do both ends of the cable. If the cables are long enough, try rotating the tank in the bottom of the cabinet to see if the hum gets any better. If none of these simple troubleshooting tips help then you will probably need to take it to a tech for further diagnosis.
 

Dacious

Doctor of Teleocity
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Mar 16, 2003
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Godzone
The reverb cable and connectors Fender uses is very cheap. It's worth getting better vintage style ones from eBay or guitar dealer. Fender had pinned the cables in a crimp pulling them tight on the one I bought, it made it noisy and intermittent: rerouting them cured that. I fitted these cables (just snip the extra small black lead short on both sides, you don't need it). Get the longer ones and run them around the inside away from the transformer, tubes and speaker

If you get 'the rattle' where the amp rings on certain notes it took a while to work out it was the tube cage rattling against the powertube beartrap clamps. You can pad the cage out with a strip of rubber or plastic, or just remove it. Just be careful if you insert the footswitch to it's Velcro holder. Enjoy the amp - my bandmate bought it from me, he loves it.

 
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Linkslover

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Posts
303
Location
Naples, FL
Thanks to Dacious and Dan40 for those wonderful suggestions.

Unfortunately, when it comes to amps, my technical expertise stops about where I can find the power and standby switches and turn them on and off in the correct order.

It sounds like both your ideas are fairly simple if you have a clue what you're doing.

1. I have no idea what tubes to use, what brands of tubes are good or how much I would expect to pay for them.

2. I also don't know which cables I would need. Snipping things sounds pretty dangerous for someone whose only truly reliable tool is a checkbook.

Any ideas how I could identify a good amp tech to try these things and what a reasonable fee would be?

Thanks,

LL
 




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