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I have a pretty new and very clean Bad Cat head in for scratchy pots. I sprayed them, but it had no effect. The volume pot has a specific crunchy are, the treble a bit less so, and just a bit on the bass pot. I measure 0.233v on both volume and treble. I wouldn't think that would be enough to make these pots scratchy? So before I go and buy and install three new pots, I wanted to weigh iin here first.
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It's weird, because it WAS working fine..... -
Circuit?Originally posted by Randall View Post
Any DC on pots produces scratchy noises when the wiper is moved. Especially if the pot is close to the input and a lot of gain follows.
But the question is, where is the DC coming from. Usual suspects are leaky (coupling) caps. Pots don't generate DC.- Own Opinions Only - -
Boutique amp, no schematic found, but I am told it is going for a blackface design. Turns out the .047 tone stack cap was leaky, it passed 141v when disconnected at the pot side. I replaced it and all is well. I would have expected to see a lot more voltage on the pot, though.It's weird, because it WAS working fine.....Comment
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200mV DC is a lot
It passed 141V into the probably 10M digital meter impedance.the .047 tone stack cap was leaky, it passed 141v when disconnected at the pot side. I replaced it and all is well. I would have expected to see a lot more voltage on the pot, though.
Combined DCR of various pots (250k 250k 10k in a Blackface tone control) plus 100k resistor may amount to a a value low enough that DC voltage becomes 1V or less depending on setting, yet whatever remains is enough to make a lot of scratch sound.Juan Manuel FaheyComment
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im working on a triple recto that has 8.2 vdc at the gain pots ! Yep... they are scratchy !
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