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TornadoHair
PostPosted: Tue Jan 15, 2019 4:23 pm 
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Joined: Thu Jan 15, 2009 9:51 pm
Posts: 35
Location: Mass.
Just finished my TMB18 build. It sounds KILLER and functions properly, all voltages are in line with the voltage chart sticky post on this page. My problem is that the Master Volume, Treble, and Bass pots on the TMB channel are all scratchy. I sprayed them, but that did nothing. The first channel's pots are fine, the scratchiness is only those 3 pots on the TMB channel. I suspect a leaky cap, but I have no clue which one, perhaps the 500pF treble cap? Is there a simple way to test for leakage without desoldering anything? Also, both guitars that I tested with had scratchy volume pots as well, but that went away when I replaced V1's JJ with a Tung-Sol 12AX7. Thanks for any help!


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TornadoHair
PostPosted: Tue Jan 15, 2019 4:25 pm 
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TornadoHair
PostPosted: Tue Jan 15, 2019 4:27 pm 
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byoc
PostPosted: Tue Jan 15, 2019 4:32 pm 
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Location: Richland, WA
I don't see anything out of place. Looks like a really nice build. If it's a cap, I'd probably start with the 500pF.

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Please do not PM me. email is prefered. keith@buildyourownclone.com
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Morgan
PostPosted: Tue Jan 15, 2019 8:43 pm 
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Location: Truckee, CA
You can also test for DC voltage at each terminal of the scratchy pots. Also, sometimes a bad ground can cause this.

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TornadoHair
PostPosted: Sat Feb 09, 2019 9:51 pm 
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Joined: Thu Jan 15, 2009 9:51 pm
Posts: 35
Location: Mass.
I jumpered in a temporary 470pf cap, and that took care of the problem! Nice and quiet now! :)
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