Jimmy Page Mod?

[Lexotron]

Hi, I'm Lex. I'm not an electronics expert by any means, so I've got a few questions.

I've had a vintage Gibson SG since I was in high school (about 10 years). Supposedly from 1961, but I can't confirm this because the serial number is mostly unreadable.

I bought it used, and I never really paid attention to the two little switches in the middle of the knobs. Recently I discovered that this might be a Jimmy Page mod (or an attempt at one), although it seems as though there are only two wires coming from each humbucker.

Attached is a wiring diagram (view from back). Sorry that there's no photos, but I only have a crappy camera phone.

Yellow is the original "Rhythm/Treble" switch, blue is the volume/tone knobs, and green is the little switches. Not shown: each of the pickup wires is shielded with a metal braid. Both are connected to ground. There is also a red wire coming from the same hole as the pickups. It is also grounded. All of the grounds are soldered together.

Note the frayed wires coming off of one of the switches. Should these be connected together?

I would be extremely grateful if someone could tell me if this wiring is correct, and if so, what do each of the switches do?

Thanks,
Lex

[David Schwab]

The switch on the right looks like a phase reversal switch. The one on the left was wired up as a series/parallel switch, but I can't tell what it was wired to.

What are those square boxes with ground symbols in your drawing? Pots?

The frayed wires used to connect to something, but not each other. This seems to be work someone started doing.

You might notice that when you reverse the phase on the one pickup that it gets noisy, because you can't wire up a pickup like that when it only has a two conductor cable.

So this has nothing to do with Jimmy Page... it's just an attempt at two common wiring mods.

[Lexotron]

Hi David. Thanks for the help :-)

Yes, the blue boxes are pots (I think). They're the back sides of the volume/tone knobs.

Sorry to sound like a complete noob, but what do phase reversal and series/parallel switches do? I noticed that when I've got the phase reversal switch on, it produces a sort of "underwatery" sound, and if I switch the guitar to "Treble" it turns off completely. Is this the intended effect?

- Lex

[David Schwab]

The phase switch reverses the polarity of one of the pickups, so they cancel out common frequencies, which is usually the low end. So you get a thin hollow tone.

The reason the signal cuts out when you switch to the treble pickups is it's not wired properly. You can't put a phase switch on pickups that have just one conductor and shield for their wire.

I didn't go through the circuit to see exactly what's going on, but I'm sure it has something to do with the single ended pickup output. You need three or four conductor wires on the pickups to do phase reversal.

[RedHouse]

Hi David. Thanks for the help :-)

Yes, the blue boxes are pots (I think). They're the back sides of the volume/tone knobs.

Sorry to sound like a complete noob, but what do phase reversal and series/parallel switches do? I noticed that when I've got the phase reversal switch on, it produces a sort of "underwatery" sound, and if I switch the guitar to "Treble" it turns off completely. Is this the intended effect?

- Lex

Hey Lex, can ya post a pic (or a link to a pic) of the guitar?