Tone controls

Put an ohm meter across them and turn them. That would be the first step

 

Odd. You may ask Wally. did you have tone stack mods. Pop the hood open, perhaps a dropped piece of solder or dangling lead from shipping travel, or other.
wish you luck.

 

If the 6.8k mid resistor's ground connection is broken the tone stack is lifted. This is how a raw switch works. Measure the resistance from the bass pot's output (connected to the mid resistor) to ground. It should measure 6.8k. It's probably an open connection.

 

Iirc, I replaced that 6.8k midrange resistor with a larger value to pump up the mids. Hopefully that connection did not go bad. Ce24, if the amp has gotten really hot and lively, what Rob describes may be exactly the problem.

 

220?

 

220 ohms to ground? Seems like close to nothing to me...

 

if that is in fact a 220-ohm resistor, that would explain the lack of action on the tone controls. Perhaps it was inadvertently placed instead of a 22k (which is what a red-red-yellow should be) why don't you check the value again with your meter?

 

You're on the wrong range. Trying to measure a 22k resistor, let alone a tone pot (typically 250k to 1m are used) will read off scale high assuming the meter will recognize it at all. Start on the highest range of your meter and work down until you get useful readings.

 

Ce24, the work order shows that I put a 22k ohm reisitor in place of the 6.8k ohm midrange resistor. If that resistor is not red, red, orange then I made a mistake. However, the amp didn’t sound as if I did make a mistake in the selection of the resistor when I shipped it off....and the tone stack has worked these many months....what 8 or 9 months? What is the date on the work order. Check my solder joints of that resistor. Measure it with one end lifted.
If in fact I did make a mistake in the selection of the resistor...the repair is on me. Ship it back..I’ll fix it, and throw in a primo NOS tube as compensation for your shipping costs, and ship it back to you at my expense.

 

Wow..wish you could get such service & honesty in the rest of the world!!!

 

Well, it seems I did make an error....proving once again I am a mere human, right? I picked up a 220K resistor....duh! Serious midrange was probably causing the movement of the bass and treble controls to be obscured.
Note to self: double check everything.