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earth crackle


steve-bbb
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just discovered i have a grounding issue but is not where i would have expected

have just recently pulled the J apart - lined the back of the pup cavities and the control cavity with adhesive aluminium tape and lifted the bridge and made sure the ground contact was good under there too - connected all the lined cavities together by crimping tags on the ends of connector cable and screwing down - as i fitted a j-retro i used the installation advice on there and connected the ground from the j-retro to another tag screwed into the cavity lining in close proximity to the tag connecting the other cavity grounds

result was great no undue noise at all even with the gain cranked right up

except from the pickup pole piece magnets themselves but only when hands not in contact with strings/bridge/control plate etc

have i done something fundamentally wrong? is there a remedy (other than trying not to touch the pole pieces when playing open strings (would rather not go down the route of new pup covers would like to keep them as is)

ta muchly in advance

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Do you mean if you touch the pole pieces when not also touching strings you get hum/buzz ? On some J PUs there is a third wire which grounds the metalwork and a copper screen - if you don't have three wires this could be why the prob. If you have three wires, perhaps there's a fault in the connection or wiring - 2 of them should go to ground. You can add a third wire to ground the pole pieces, need something to spring contact with them inside the PU it's fairly tricky. Or get 3 wire variants !

HTH!

LD

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[quote name='luckydog' timestamp='1471122602' post='3110724']
Do you mean if you touch the pole pieces when not also touching strings you get hum/buzz ? On some J PUs there is a third wire which grounds the metalwork and a copper screen - if you don't have three wires this could be why the prob. If you have three wires, perhaps there's a fault in the connection or wiring - 2 of them should go to ground. You can add a third wire to ground the pole pieces, need something to spring contact with them inside the PU it's fairly tricky. Or get 3 wire variants !
[/quote]
no third wire - they are wizard hammers - will not be replacing them because they took me a while to track down a pair on here and they sound flippin fantastic :D - they might be tinkerable will have to investigate i think the black plastic cover is removable and they are not all resin or wax dipped so could be an option
[quote name='NancyJohnson' timestamp='1471164845' post='3110862']
Shoot a message to Rich/Grangur. I had a similar issue on a (Precision style) passive circuit. Grounding problems...buzzing stopped with a finger on the tone, increased if you touch the pickup pole.

He's advised the issue has been resolved quite simply (something not connected).
[/quote]buzzing stops when you touch any other item that is grounded - cant say have noticed if the buzzing varies with the tone swell will give it a try this afternoon - thanks will message rich/grangur :)

Edited by steve-bbb
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[quote name='steve-bbb' timestamp='1471165568' post='3110874']no third wire - they are wizard hammers - will not be replacing them because they took me a while to track down a pair on here and they sound flippin fantastic :D - they might be tinkerable will have to investigate i think the black plastic cover is removable and they are not all resin or wax dipped so could be an option
[/quote]

OK, so the pole pieces prob aren't grounded in those PUs, which is the issue. Think I'd say 'just live with it' since they sound great! It's tricky grounding the pole pieces reliably, and means taking the PU apart usually which is high scoring. In practice, you won't touch the pole pieces whilst playing ?!

Enjoy !

LD

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I had that problem in a bass once. My quick fix was a couple of coats of quick-dry transparent nail varnish over the polepieces. Then if you touch them they don't make a noise.
The long term fix was simply putting a strip of copper shielding under the pickup, ensuring it touched all the polepieces (easier on a Stingray type pickup than in a Jazz, but doable)... then ground that strip.

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sooooo,

i got my little tool box out and removed both pickups and armed only with a roll of black insulating tape, a roll of adhesive aluminium shielding tape and soome offcut pieces of high density foam (from an old army issue sleeping mat as it happens) i have grounded out the underside of the pole pieces to contact with the screening which lines the base of the pickup cavity - all contact only through the pressure created by the high density foam - which begs me to ask why do manufacturers only put a silly small piece of low density foam under the centre of a pickup so that it rolls around like a stuck pig when you try and use it as a thumb rest

crackling all gone - whole thing running fairly quietly (considering the mahoosive gain and output from the John East)

problem solved - thanks for all your input

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