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Vintage threads from the first ten years

Tweed Champ Volume Control

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6/20/1999 11:35 PM
Mook	Tweed Champ Volume Control I just installed an Alpha 1M Vol Pot in a Tweed Champ. Old one was scratchy. The new one works fine except when the volume is "off". When the volume is turned all the way down (or "off") it makes a hum. Ideas? Mook

6/21/1999 5:54 AM
anonymous	Mook, Double check the ground coming off of the new pot. I assume the ground for the pot is the standard mount to the chassis and not star ground? If there is a bad ground conection at that point the grid of the second triode is being lifted and could be causing the hum. Good luck, Benjamin

6/21/1999 12:14 PM

Hi, Mook. I agree with Ben that it may be a ground. Perhaps, does the old and new pot have the ground lug of the vol pot soldered to the pot case? If so, your ground from the pot case to the chassis may be at fault. As an example, I haven't been able to get a good solder ground to a Mouser pot case. Try a wire from the ground lug of the pot to a ground point on the tag board, maybe on the cathode resistor from the first tube stage?

6/21/1999 8:00 PM

You'll have to mechanically scrape the chromate plating off the pot cover to expose the bare steel underneath before soldering. This can be done with a file, sandpaper, or a sharp screwdriver tip. As you're heating the bared spot with your iron, try to melt a tiny bit of solder and smear it around to "tin" the steel, adding more solder a little at a time to obtain a molten puddle about 1/4" to 3/8" diameter that is bonded to the steel. After the puddle cools, go back and remelt it while pressing the pre-tinned lead you wish to connect down into the puddle (you might need pliers, it's too hot to hold w/fingers), hold it there after removing heat source until the puddle frosts over.

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