Wiring Help.. Earth buzz..

grappagreen · September 2023

Hi all,

Finally got around to rewiring my old '86 Hamer Chaparral this weekend after a recent refin.

Was a challenge given that I couldn't find an actual wiring diagram for this version but I thought I had enough to work with. Everything works but I get a pretty terrible earth buzz in any setting - even all pickups in the 'off' position. This reduces when I touch the strings/trem etc. Problem is that I've metered for continuity and everywhere I think I should see it, I do.

I've included some photos but just in case anything is unclear the setup is volume, tone (mid-range control actually), 3 off 3 way mini-toggles with neck and bridge offering phase reverse and neck offering coil split. I purchased replacement toggles. The only thing I wasn't 100% sure about were the earth wires from the pickups which I popped to ground.

Any help or advice really appreciated.

Si

jasonbone75 · September 2023

Have you checked for continuity between your earth and the bridge? You need a wire from the earth to the base of bridge or posts depending on the configuration.

grappagreen · September 2023

jasonbone75 said:

Have you checked for continuity between your earth and the bridge? You need a wire from the earth to the base of bridge or posts depending on the configuration.

Thanks for coming back.

Yes - bridge (Floyd) is earthed back from trem claw and shows continuity.

Sporky · September 2023

If the buzz reduces when you touch the strings then the wire to the bridge must be in place, and the noise is from a lack of shielding.

When you touch the strings you are earthed through the guitar (and thus amp), and your body then acts as a shield.

grappagreen · September 2023

Sporky said:

If the buzz reduces when you touch the strings then the wire to the bridge must be in place, and the noise is from a lack of shielding.

When you touch the strings you are earthed through the guitar (and thus amp), and your body then acts as a shield.

Thanks Sporky. Appreciate it.

What I can't understand is that everything is as it was before (other than the fact I've rewired and replaced the old toggles) and it never buzzed before..

Si

Sporky · September 2023

That is odd.

I don't think this fits the behaviour, but have you checked you've got the jack wired up the right way around?

grappagreen · September 2023

Sporky said:

That is odd.

I don't think this fits the behaviour, but have you checked you've got the jack wired up the right way around?

Thanks..

I have; tip is live and shield to ground..

jasonbone75 · September 2023

I would grab a length of wire and try grounding the backs of pots to the foil shield to see if that improves things. If it is an improvement solder that connection in place.

ICBM · September 2023

Check all the ground connections, especially to the cable shields - don’t rely on contact between the pot casings and the shielding plate. If that’s an unshielded cable to the jack, replace it with shielded.

grappagreen · September 2023

Thanks all.

@ICBM - is it actually better to insulate the pots from the shield plate and then wire to earth? Does such a thing as a ground loop cause issues? I'll replace the jack cable as it is un-shielded..

Si

ICBM · September 2023

grappagreen said:

@ICBM - is it actually better to insulate the pots from the shield plate and then wire to earth? Does such a thing as a ground loop cause issues?

No - there is no such thing as a ground loop within a guitar. Ground everything, don't worry about duplicating a connection.

grappagreen · September 2023

ICBM said:

grappagreen said:

@ICBM - is it actually better to insulate the pots from the shield plate and then wire to earth? Does such a thing as a ground loop cause issues?

No - there is no such thing as a ground loop within a guitar. Ground everything, don't worry about duplicating a connection.

Brill - appreciate it..

Sporky · September 2023

And I'll repeat my personal hobby horse - don't solder anything to the back of a pot. It's harder than having a central screw with a loop of solid core wire for the grounds, and there's a real risk of damaging the pot innards.

grappagreen · September 2023

Sporky said:

And I'll repeat my personal hobby horse - don't solder anything to the back of a pot. It's harder than having a central screw with a loop of solid core wire for the grounds, and there's a real risk of damaging the pot innards.

Thanks - I'll give it a go!

Si

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Wiring Help.. Earth buzz..

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