What kind of pot is this??? Please help!

[joeowl]

The guitar is an Epiphone Nighthawk, made in Korea 1997.

Can anybody please explain me what is this "fungus grown" on a tone pot? Its function?
The tone blend works. At this moment, I can't hear any difference in behaviour from a standard tone pot. To me it looks like some kind of "Q filter". On one side it has a cond soldered to ground, on the other it goes to the main switch, soldered in place of the neck pu position. In standard (no split) mode the neck pu doesnt work.

Thanks

Attachments:

[newey]

owl-

Hello and Welcome to G-Nutz2!

It's hard to tell much from pictures of the back of the pot. Does it have 4 connections to it, or only 2? And, what does Epiphone state that this is supposed to do? A regular tone pot or something else? (I'm unfamiliar with the specifics of a Nighthawk, and whether the Epi version is the same as the Gibson or not).

I doubt it's any type of Q-filter, it looks to be just a sealed type of pot- military spec pots are often sealed like this to prevent dust incursion. But it may be a "dual gang" pot- that's why I asked about the number of connections.

[joeowl]

Thanks for having me and replying!

I just made a better picture. Shown is the lover part of it. Underneath, if you look carefully, is a standard tone pot.
The part in question is removable, not connected to the pot shaft (has no rotating parts), hence no dual gang. It has a brass clip soldered to the pot cap that holds it in place. It has 2 wires, as I mentioned, one goes to cond and ground, the other was soldered to the switch. No direct connections from the tone pot lugs to this part.
I just wired it directly to see what it does... it makes the sound darker, like a standard tone blend, but it also may be due the cond I suppose.

I searched the web and I can't find the original wiring schematic from that "epoca" The only "fancy" part is a mini toggle which splits the humbuckers.
Nowadays they put a superswitch and a push-pull pot, but no mysterious, mumbo jumbo like this

I'm confused mostly because it looks like a factory made wiring. You know, clean solder, right amount of tin...
PS. Being a repair man with some experience I saw and did almost any wiring imaginable. Sadly I have not formal education in electronics... and in this case I regret it!
 

[newey]

OK, the mystery deepens. I'm not clear on wxactly how it's wired. When you say it "goes to the switch", is it switched in/out of the circuit?

Some sort of an inductor would be my only guess. But that's all it is- a guess.

[b4nj0]

It looks like a potted inductor, possibly two cores stacked? Didn't Nighthawks have some kind of Varitone fitted? (Maybe not every Nighthawk). The way the connections are described as being instead of the pickup at the switch tag, it's not really surprising if the neck pup is mute. Is there one or more seemingly redundant capacitors anywhere? With some intuitive re-wiring, the neck pup should sing once more and the inductor could probably be put to better use. Like newey- I'm only guessing...

e&oe...

[joeowl]

Aug 7, 2017 6:34:06 GMT -5 newey said:

OK, the mystery deepens. I'm not clear on wxactly how it's wired. When you say it "goes to the switch", is it switched in/out of the circuit?
Some sort of an inductor would be my only guess. But that's all it is- a guess.

Here's a pic of the wiring as is. I found out that the com1 and com2 of the 5way selector are somehow "jumped" (not visible). I mean that both sides of the lugs go to both com1 and com2 at the same time. This may be a factory switch, but as we know, this is not usual on CRL style. It's an "eastern" enclosed type switch - since it's korean it makes sense. I'm not very familiar with those. This may be one part of the problem, but if they are separated, they loose the middle pu. in the "humbucker split" position of the mini toggle. Hmmm??? The second strange thing is the mini hum wired on the middle lug and the out (?) of the inductor to the "neck pu" lug...

Aug 7, 2017 8:21:02 GMT -5 b4nj0 said:

It looks like a potted inductor, possibly two cores stacked? Didn't Nighthawks have some kind of Varitone fitted? (Maybe not every Nighthawk). The way the connections are described as being instead of the pickup at the switch tag, it's not really surprising if the neck pup is mute. Is there one or more seemingly redundant capacitors anywhere? With some intuitive re-wiring, the neck pup should sing once more and the inductor could probably be put to better use. Like newey- I'm only guessing...

e&oe...

Seems it has two stacked cores. Not familiar with Nighthawks. However this should be quite different from variotone. It resembles me the Bill Lawrence Q filter www.wildepickups.com/Q-filter.html
There was a video on youtube made by Bill himself, but I can't find it now.
I can't see the logic to use both tone pot and inductor at the same time. Maybe once the pu are splitted has more logic... who knows... Not a fan of "fancy" stuff. For me a standard tone pot with a good cap and adequate value is the best.

The guitar is rewired without the "inductor" and it now works fine.
The question of how the factory intended to be still remains...

Thnks guys!

[blademaster2]

That items looks *very* much like the ferrite shells that are used to wind custom inductors, so I would conclude that this is a ferrite-core inductor.

In my own guitars I have 1000mH inductors in the tone circuit, and I was inspired to do this by the 800mH air-core inductor that I discovered in the tone circuit of my Framus Nashville deluxe. In your guitar it appears to be a switchable feature and not part of the tone control.

PSPICE modeling showed that the second-order shunt formed by an inductor and capacitor can preserve more of the high frequencies of the attack while attenuating (scooping) the high-mids. Essentially the tone inductor forms a divider with the inductance of the pickup coil and limits the high frequency attenuation above a certain frequency range.

This makes the guitar sound subdued and thinner without entirely losing the clarity of the attack that I experience with other capacitor-based tone controls, and I like this on my guitars where I use it on the bridge pup. I have always called it 'fatness control'.