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John East preamp crackling loudly - any ideas why?


Mike
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Hi all

Picked up a Lakland jazz today with a JE Preamp in it - unfortunately, it's crackling loudly when I play. Not constantly, but every 3/4 seconds. It hums loudly when you touch the string and the crackling gets worse.

Any ideas? I'm not good with wiring etc but if you speak to me like a child I'll be happy to have a go.


Thanks in advance

Mike

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[quote name='Mike' post='309917' date='Oct 19 2008, 05:04 PM']Thanks for the replies - battery is brand new.

I've taken some pics of the guts:



I've also written to John East but all your input gratefully received also![/quote]

Sounds more like a component problem, I would wait till John contacts you.

As a bass builder I am intrigued by the above picture.
Having never owned a Lakland could you tell me if the shielding is factory fitted, and are those chips in the finish around the screw holes ?

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[quote name='Mike' post='309955' date='Oct 19 2008, 06:12 PM']Yes, they are chips - the one furthest away is particularly bad. I am not 100% sure if that is the original factory shielding - I've got no reason to think otherwise.


Regards

Mike[/quote]

Hi Mike
they are caused because the pilot holes haven't been countersunk on the finish to stop it cracking as the screws go in. I would get a drill bit and manually (by hand) just carefully dress the holes otherwise they may get worse.

cheers Paul

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I can't see a ground wire coming from the bridge to the controls, does it make the noises when you don't play it? Does it make the noises in active and passive mode? Can you give me more details. I have a J retro that I fitted and a U Retro, so hopefully I can help. It is probably a grounding issue or it could be that the tops and bottoms of the control knobs are breaking contact, PM me and I'll give you details.
Steve.

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Hey Steve. I think you've got it. The crackling doesn't tend to happen when nothing is played, though there's a buzz. When I play, it crackles a lot. When I play keeping one finger on the bridge, there is no crackle.

How do I ground this?


Thanks for your help and input!

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If you have a tunnel from the bridge to the control cavity, simply get a piece of wire, splay the end and put it under the bridge, solder the other end to the back of a pot or better still, check out the Lakkie schematics to see where a bridge ground should go.
Also, get in touch with John to supply the copper springs that go in between the knob stacks to improve contact between the top and bottom parts of the stacks.

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