Pot values on '64 with Todd frequency tested pickup

[Smiert Spionam]

I'm working on a cool little M-65 with a Todd pickup, and I assumed that the reason it sounded so dark was that it had a mud capacitor. There wasn't one on the pickup itself, so I pulled the harness (ugh). The pots are original Centralabs with matching codes (1346323); they also say "S-200", which I haven't deciphered yet.

The weird thing: the volume pot reads 5k, and the tone 800k. I'm not kidding, and I checked my meter against multiple other known good pots. I will try cleaning them, on the off chance that it changes anything -- but is it possible they have drifted this much?!?

 

[matsickma]

I suggest you add a few droplet of contact cleaner down the tone pot shaft and squirt some in the pot cavity. Proceed to turn the knob on pot back and forth. Normally pots are self cleaning but the have to constantly be used. Hopefully with a little time the cleaner and shaft rotation will clean it up. For a 5k pot to read 800k resistance their has to be damage or corrosion to the pot.

 

[Smiert Spionam]

I've done that a few times, with no change in values -- and they move freely. Will do it a few more times. I'm wondering if they may have actually installed that 5k volume pot intentionally, as an alternative to a mud cap? That wouldn't explain the identical tone pot reading 800k, though.

 

[SFIV1967]

The weird thing: the volume pot reads 5k, and the tone 800k.

I would have thought both would be 200kohms pots...Which maybe the S-200 could mean. But 5k ohms and 800k ohms? Something is wrong with those pots I'd say.
The 47nF capacitor is probably good. Looks undamaged.

Ralf

 

[Smiert Spionam]

I would have thought both would be 200kohms pots...Which maybe the S-200 could mean. But 5k ohms and 800k ohms? Something is wrong with those pots I'd say.
The 47nF capacitor is probably good. Looks undamaged.

Ralf

That was my thinking, too -- 200k would be reasonable. 5K and 800k... not so much!



And thanks, all -- I appreciate the sounding board!

 

[matsickma]

I just realized that I misunderstood the pot resistance values. Yes...5k Ohms is way out of line. The Vol pot may be the culprit. Do you have the ability to buy pass the controls to verify the tone of the pickup? Then add a 500k ohm VOL pot.

 

[GAD]

Are you measuring the post while they’re in the circuit? If so, that can produce unexpected results.

 

[Default]

Not contact cleaner!!!!!!
That will trash the carbon paths in the pot. Use control cleaner! Some people swear by wd40, I haven't tried that. Iirc, the tone pot on my Starfire's neck pup is 200k.

 

[matsickma]

Oops...I better check what I have been using. Multiple cans around. Last one I used was from Radio shack! I have used WD40 in the past.

 

[BradHK]

Deoxit F5 is what I would recommend.

 

[Smiert Spionam]

I'm using F5 -- wouldn't use straight contact cleaner on old pots. I was an idiot about the volume pot value, though -- I still had the pickup connected when I was testing it, so I was measuring... the pickup.



After more light cycles of flushing and cleaning, I think I'm back in business -- sounds much better. Now, to fully reassemble it -- this time with a longer ground wire so I don't have to remove the tailpiece next time (if there is one).

Thanks, all.

 

[GGJaguar]

I think I'm back in business -- sounds much better.

Excellent! Vintage tone lives on!