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I had a problem with 1 or 2 pots, I've sprayed a contact cleaner, then disconnected them from the board on which they are soldered. Measuring them disconnected they are good. After resoldered I measure a much higher resistance, over the scale of the tester, both between central and one side pin or between side pins. Maybe deformations due to soldering do not allow right contacts? Anybody ever had similar problems?
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Try this, reverse your meter leads and measure again. Try measureing one way then the other with your probes. DO you get a very high reading one way, then a "negative resistance" reading the other? If so, that means there is probably a little voltage in the circuit. Like some charge left in a cap. I hope you are not making resistance readings with the amp turned on.
If the pot measures good out of circuit, then it is likely to be OK in the circuit. Your meter is being confused by the other things in that circuit.
If there is no residual voltage in the circuit, your meter should read the same both directions...
just like your name.Education is what you're left with after you have forgotten what you have learned. -
Originally posted by Enzo View Post
Thanks Enzo. The amp was turned off. Maybe some cap voltage as you say ...
With amp turned on the effect is that 'bass tone' pot acts as a sort of volume pot. With amp turned off I've made the strange measure explained. You say that a charged cap in parallel could cause the effect of increase the tester reading ...
The circuit is this
http://www.drtube.com/schematics/marshall/4210.gif
The 2 pots I'm speaking about are the volume and the bass pots on the clean channel (all left in the schematic).Comment
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The schematic linked in the previous post was modified in this way:
http://music-electronics-forum.com/a...9&d=1197309267
As you see in parallel to the clean channel's tone stack there is a a 22n cap which then goes to the crunch channel, which is put to ground in the clean mode. Could this addition cause the trouble whith the bass pot of the clean channel? (it acts as a sort of volume pot). Sometimes it works good ...
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