SOLVED High frequency tone after routine repair

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michaeleschuler

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I was assisting someone with replacement of a DPDT switch in a Wounded Paw Battering Ram overdrive/fuzz pedal (an old v 1.0 model). The replacement of the switch that actuates the fuzz circuit was trivial and the new switch works fine. I also applied Deoxit D5 to the jacks by spraying it on plugs and inserting them repeatedly, and I applied it to the pots I could access via their bottom vents, but there was some overspray.

After allowing it to dry for about 15 minutes I tested it, and it sounded fine initially (a minute or so), but then it developed a high-pitched whine when just the fuzz switch is actuated. This doesn't appear to be switch related; it appears even if I jumper around the switch. I tried reseating/swapping out the dual op amp IC, but no effect. I also tried blowing out the enclosure with canned air to see if something might be bridging a trace or component. The replacement didn't appear to disturb anything and I don't see any component issues but I can't access the trace side of the circuit board. The attached photo is post-replacement.

Any ideas for a solution or troubleshooting? Suggestions for a repair person in the Pacific Northwest to contact?
 

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Did you change the wiring with the footswitch?

If the wires were routed further apart before (like the other footswitch), you might be experiencing some oscillation due to the input wire being so close to the output wire.
 
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I will check to see if any wiring got shifted around, possibly when I was trying to access the pots to apply the D5. The existing wiring didn't allow me much room to adjust the placement of the signal wires, but I'll check my before and after images to verify.
 
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OK - I think I've traced the issue to the power supply: When I run the pedal using a battery (via the external jack) or the power supply from my pedalboard, I get no noise. When I run it using the Dunlop 9v wall wart that I use for testing, I get the noise, but only on the fuzz channel. I did not get any noise prior to the switch replacement when using this wall wart or on any other pedals I've worked with. I noticed this when I moved the wall wart cable and picked up a bunch of radio interference, so maybe it is failing intermittently? But the noise was present even when the fuzz knobs were completely down, so?

I did check the pedal wiring, moving the wires around with a wooden probe, and did not find any changes to the signal. The only wires that had moved were the battery clip wires, and I relocated them, but it had no effect.

Robert--Thanks for the assistance. If you hadn't suggested checking the wiring I might not have found this anomaly.
 
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falco_femoralis said:
The noise might be oscillation from your simple power supply which is amplified by the fuzz.

Do you have another power supply? Like a nice Voodoo Labs one that has on board filters and is made to provide clean power for pedals?
Click to expand...
I'm going to test the Dunlop supply with some other high gain pedals to see if I can replicate issues on them and will check that wall outlet to verify that it isn't an issue with the house wiring on that circuit. The pedal worked fine when run using my 1Spot pedalboard supply.
 
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