Volume pot problem

[tjcurtin1]

The bridge pup on my Wildkat stopped working, so I pulled the pot out to check it. Meter readings seemed to indicate something wrong with the pot, so I ordered a CTS replacement and installed it; I did check it with the meter before installing and it read fine. In the guitar, however, I only get sound with the pot at just about the middle position - say from 4-6. Outside that range it is dead, and even in that range the sound cuts in and out. The only wiring glitch that I can think of is that I wired the input from the pup to the wrong lug, but would that cause a problem like this? Or did I get a bad replacement pot?

Thanks guys!

[marnold]

I'll leave this up to DVM, but I would definitely double-check to make sure everything is wired correctly. Not that I have any experience in mis-wiring things *cough*

[duhvoodooman]

I assume this is the bridge-specific volume pot and not the master volume we're talking about? Have you confirmed that all the other controls, including the 3-way switch, are working correctly? A bad CTS pot, while possible, would seem to be a long-shot, esp. since you tested it and it looked fine.

Do you have a wiring diagram for the guitar? Or maybe a link to one?

[duhvoodooman]

Found this online--look right?

https://cdn.shopify.com/s/files/1/0730/3803/products/9240_2F1487945141_2Fwildkat_1024x1024.png?v=148794 5190

[tjcurtin1]

Thanks, DVM - yes, that's the wiring diagram, and it is the bridge specific control. With the old pot, when I shorted the pup input/output lugs, I would get full volume on the pup with a lot of hum, which got less if I touched the bridge. With this pot in, if I short those lugs I get the hum, but not the full volume (this was an accidental discovery which I mention in case it proves diagnostic in any way). The other controls work fine with the neck pup - with the selector switch I always get the neck pup in both the rhythm and the combined position and I get the bridge, too, in combined and lead position when the pot is working. Master volume and both tone pots also working as normal.

[duhvoodooman]

I would suggest this as a quick test to see if the problem is with the new pot or how it's wired: Disconnect both hot wires from the lugs of the bridge pot and connect them together. In other words, you're bypassing the pot completely and running the pickup output directly to the 3-way switch. Leave the ground wires connected to the back of the pot and be sure they are making solid connection there. You also need to have that third "unused" lug grounded to the pot. See how the guitar sounds once you've got that all checked out.

I would also suggest checking to make sure your three ground connections on the 3-way are all solid/intact.

Side comment: Gotta admit I don't like how long the ground wire runs are on this guitar, which I think are more prone to developing problems. The 3-way on the Wildkat is a l-o-o-o-n-n-n-g-g way from the two volumes and the tone pot. Much prefer the usual Gibson practice of running ground connections directly between the backs of the pots rather than up through the 3-way. Example HERE (http://www.seymourduncan.com/wp-content/uploads/2016/05/2H_3G_2V_1T.pdf), though it's for humbuckers and no master volume.

[tjcurtin1]

Thanks again, Vood - when I connect the hot leads, I get the bridge pup full blast, with all other controls working properly. Since that was the case, I went ahead and reversed the lug positions of the hots and I have the same problem - one small area in the middle of the run of the pot that gives me a connection, albeit at the volume that you would expect for that position (ie, less than full volume). It is cleaner now, that is, there isn't scratchiness and drop out - it's on when in that sweet spot and then off when you go by it...

Yes, there are several posts on line about the length of the wiring in the Wildkat and the fact that the factory wire adds a lot of capacitance to the circuit, dulling the sound of the pickups. I remade the harness last summer with low capacitance wire, and the guitar did sound brighter and clearer as a result. It had worked fine since then until the other day when I plugged her in to find no bridge pup...

Ted

[duhvoodooman]

Sure sounds like you got a defective pot. I'd contact the vendor and have them replace it....

[tjcurtin1]

Here's the latest - I checked the old pot now that it was out and it seems to test fine...?? After twisting the new pot wiper back and forth absentmindedly while I thought about the problem, it's range gradually increased so that it was working normally - except from 9 1/2 to 10, where it still cuts out. THEN, I happened to turn the pot so that the shaft was facing up, and voila, the pot works normally! Turn it to the side or facing down and it has the bad spot between 9 1/2 and 10. What the heck is that about?!?!

[duhvoodooman]

Definitely sounds like an internal defect in that pot. The wiper must not be making contact with the resistive material track in that short section of the sweep. Sounds like the little bit of added force of gravity on the wiper causes contact to be made when the shaft is straight up. Contact the vendor and insist on a replacement. That shouldn't happen even with a cheap pot, much less a CTS.

http://www.electricaltechnology.org/wp-content/uploads/2015/01/Potentiometers-Construction.png

[tjcurtin1]

I put a few drops of tricloroethane in the pot and swished the wiper back and forth, and all is fine now. I did notice, though, that even this little bit of solvent took whatever dampens the throw of the wiper, so it turns more freely than originally, but everything is working fine now... I still wonder about the original problem, since the original pot tests as fine now that it is out of the guitar... Again, thanks for the benefit of your experience, Vood.

[duhvoodooman]

Glad to hear that took care of the problem, but don't be surprised if it returns, though hopefully not. I suspect that the original problem was a bad connection somewhere, and it got fixed by replacing the pot and re-doing the solder joints.

[tjcurtin1]

Yes, I've found already with my limited experience that any little oddball thing can make a mess of things - when I first put the new harness in, I had a glitch because one of the pot lugs (or perhaps it was a stray strand of wire) made contact with the shielding paint and caused a short...