Non-functional tone pot.

[rrybicki]

Hi All,

I have a very nice Kramer DMZ 4000 that I am inordinately fond of. Unfortunately, for some reason the tone control seems to be not functioning at all. I have checked the control cavity and not found anything amiss. The tone pot seems to be working, using my meter I found a smooth range from 0 to 515 K ohms.

Any ideas where to look next? The caps, perhaps? And how could those be troubleshot (troubleshooted?)?

If anyone has any suggestions, I would be very grateful.

Thanks a lot,

Russ

(photo of control cavity...)

[Jazz Ad]

The link between the ground cable from the tone pot and the bridge ground seems lousy. Is it even soldered? It looks like it's just wrapped.
The cap may also be shot, although in this case the typical effect is the tone pot acting like a volume.

[rrybicki]

Jazz Ad,

Thanks very much for your help. Although the wires look simply wrapped, they are soldered and the connection is sound. I tried testing what I could with my meter and could not find an open connection anywhere.

Of course, my electronic skill set is not so strong.

Should I just try replacing the cap as the most logical next step?

Cheers,

Russ

[Stone Soup]

There are three lugs on your tone pot. One is soldered to the body of the potentiometer, the center one is attached to a capacitor and the third one is not used. Is that one touching the body of the potentiometer? If it is, bend it back so it doesn't touch anything. I'm no real an expert, but that is what I would try, first.

[rrybicki]

Stone Soup,

I double checked, and the open tab is not shorted to the body of the pot. I bent it a bit farther away to be sure. Thanks for the suggestion, though!

I tried swapping the capacitor with an identical one I found in my parts box. It had no effect.

Removing the capacitor entirely (leaving the leads open) had no effect.

Removing the capacitor entirely and jumpering the leads togther caused the tone pot to act as a volume pot, as correctly predicted by Jazz Ad.

Stumped.

Thanks for all your help guys, it is appreciated!

Cheers,

Russ

[Stone Soup]

What you have is basically a P-Bass setup, wiring wise. I would opt to wire it like a P-Bass.

I don't understand the second capacitor across the two lugs on the volume pot. I could see a resistor being there to change the value of the pot, but not a capacitor. Did you put that there? I found out the second cap on the volume pot is a "treble bleed". It allows highs to bypass the volume control.


Here is a Kramer diagram for a guitar, but it's the same circuit. It looks like you
have the large capacitor attached to the wrong lug on the volume pot.

[rrybicki]

Thanks guys, for all the help.

I rewired according to the 4-conductor P-bass wiring schematic from Rothstein and all is now good. It's designed for a four lead DiMarzio pickup and series / parallel switching.

linky

Thanks again and Cheers!

Russ