Norlin Era LPC Bridge Ground??

In prepping for a complete electronics rebuild on a 1980 LPC, I am curious to know if anyone can advise where the stock bridge ground wire ties in to the ground loop. In the control cavity? If so, its not obvious. I have read that people have found this coming into the control cavity nearest to the neck volume pot (via a very small gauge wire) but I see nothing. No drilled holes and no small gauge wire.

Could it be tied to the bridge pickup ground within the bridge cavity and then fed into the control cavity via the switch wire bundle?

Thanks

PTBeezer said:

In prepping for a complete electronics rebuild on a 1980 LPC, I am curious to know if anyone can advise where the stock bridge ground wire ties in to the ground loop. In the control cavity? If so, its not obvious. I have read that people have found this coming into the control cavity nearest to the neck volume pot (via a very small gauge wire) but I see nothing. No drilled holes and no small gauge wire.

Could it be tied to the bridge pickup ground within the bridge cavity and then fed into the control cavity via the switch wire bundle?

Thanks

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The bridge makes the ground connection through the strings.
Maybe you meant the tailpiece?

Being a 1980, it's very possible that it never had a ground wire installed at the factory.

Strings Jr. said:

Being a 1980, it's very possible that it never had a ground wire installed at the factory.

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How right you are. After poking and prodding around and finding a suspiciously wire shaped bulge in the over-spray of the control cavity, I found this...

Lifted it slightly at the end so it becomes more visible. It was literally mashed into the route and hard to see.

After viewing several examples from 1980 from the internet, its amazing that NONE of them appear to be grounded.

Tom Wittrock said:

The bridge makes the ground connection through the strings.
Maybe you meant the tailpiece?

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Yes, Tail Piece. Mystery solved in the reply above....

Really sad that such a good looking great playing guitar had such a weak link in the manufacturing chain...

If it has no ground wire it would have originally had a metal shielding can that screwed to the metal base plate and enclosed the control cavity.



The jack sockets were also enclosed in a metal case so all the electrics were enclosed. This actually provided good shielding without the need for grounding the tailpiece but unfortunately many of these have been removed and lost over the years meaning that unless a tailpiece ground wire is added or the can replaced then the guitar will be susceptible to RF and electromagnetic interference.

PaulD said:

If it has no ground wire it would have originally had a metal shielding can that screwed to the metal base plate and enclosed the control cavity.

The jack sockets were also enclosed in a metal case so all the electrics were enclosed. This actually provided good shielding without the need for grounding the tailpiece but unfortunately many of these have been removed and lost over the years meaning that unless a tailpiece ground wire is added or the can replaced then the guitar will be susceptible to RF and electromagnetic interference.

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Yep, this one was a case queen and literally barely played. All original parts. The metal case "ash tray" is intact and all parts are original.

In working with Rand Jackson Luthiers on a complete re-wire, thats when the ground issue came up. My guess, after discovering the tail piece ground buried under the over spray, is that perhaps the intent of Norlin era was to ground the strings through the metal case. But after looking up numerous 1980 cavity photos, almost all appear not to have a grounded tailpiece (zero evidence of any ground wire coming into the control vanity). This would certainly cause a ground hum / buzz. Maybe the myth of the special metallic silverburst paint helped in closing the ground loop.

Long and short, mine did have a tail piece ground wire but it was smashed into the side of the cavity. It must have somehow been making contact with the metal case / metal control board thus eliminating any potential buzz. Not being a fan of touching a hot mic with improperly grounded equipment, I think my re-wire is going to be a completely different looking animal to that of the original 1980 construction techniques.

PTBeezer said:

My guess, after discovering the tail piece ground buried under the over spray, is that perhaps the intent of Norlin era was to ground the strings through the metal case. But after looking up numerous 1980 cavity photos, almost all appear not to have a grounded tailpiece (zero evidence of any ground wire coming into the control vanity). This would certainly cause a ground hum / buzz.

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No, the whole idea behind having the cavity enclosed in the metal can was that the strings would not need to be grounded, if properly implemented this should (in theory at least) result in a guitar that is just as quiet as one where the strings are grounded with the added advantage that there will be no increase in noise if you remove your hands from the strings. I believe that they continued to drill the hole for the wire (and possibly installed the wire) as this was just the way they had always made them but just didn't connect the wire in the control cavity.

PTBeezer said:

Not being a fan of touching a hot mic with improperly grounded equipment, I think my re-wire is going to be a completely different looking animal to that of the original 1980 construction techniques.

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Your guitar is actually much safer with the strings not being grounded, if there is fault resulting in a microphone or your amplifier chassis becoming live then without the strings being grounded there is no path to ground through you so you would not get a shock.