Grounding issue ?

[Machines]

Since installing the new pickups on my Jazz, there's a definite buzz/hiss and i'm not touching the strings (volume has to be quite high though). This happens on all pickup configs.. any ideas chaps ? I'm aware single coils are liable to it but I don't remember hearing it with the stock pickups..

Cheers !

[Hamster]

A few possibilites.

A bad solder joint when you swapped the pickups - probably the earth as it effects any pickup configuration?
Line the pickup/control cavity with tin/copper foil.
Change the hook up wires to shielded ones.

Good luck!

Hamster

[EBS_freak]

[quote name='Hamster' post='249402' date='Jul 28 2008, 09:57 AM']A few possibilites.

A bad solder joint when you swapped the pickups - probably the earth as it effects any pickup configuration?
Line the pickup/control cavity with tin/copper foil.
Change the hook up wires to shielded ones.

Good luck!

Hamster[/quote]


Ah yes - another Nordstrand trait. Did you get the complete single coil or the split coils?

I doubt you will get rid of it completely but this is what you do to calm things down a bit.

Line the control cavity with self adhesive copper or paint the whole of the inside of the control cavity with shielding paint. On any joins on copper, place a blob of solder across the join. (Use copper because you can't solder to aluminium) Paint - its more expensive - but ultimately it is easier. No soldering and no need to make awkward cutouts to line the cavity. Make sure you put a good few coats of it on though - one or two coats is pretty useless. I would paint three coats as a minimum. Make sure there is a paint/copper link from the control cavity up to the screws on the control plate (I presume you are talking about screening your jazz - although your MM would be similar). Completely screen the rear of the scratch plate - paint it with the shielding paint or screen it with copper foil. Link that to the control cavity or the control plate also. Make sure there is screening paint/shielding around the screws on the body where the scratch plate is screwed into.

Replace all the cables on the preamp with shielded cable. Take the bridge off, remove the crappy earth cable and replace it with a decent thick copper ground.

That should clean things up nicely. Be careful that you don't short any of your connections in the cavity though! If you wanted to go really hardcore, you could shield the pickups themselves... but then again, that may be going too far.. and it will no doubt have some effect on the performance of the pickup in terms of natural sound.

Dude, as I said earlier... the hype outplays the performance.

Edited July 28, 2008 by EBS_freak

[Machines]

I'll give it a try with the paint.. where would be the best place to get it ? Will check out the earth solder joint too..

Of course it's fine if I roll off the tone control, or don't let go of the strings .

Cheers chaps.

[EBS_freak]

[quote name='Machines' post='249487' date='Jul 28 2008, 12:12 PM']I'll give it a try with the paint.. where would be the best place to get it ? Will check out the earth solder joint too..

Of course it's fine if I roll off the tone control, or don't let go of the strings .

Cheers chaps.[/quote]

ebay is your friend...

[url="http://cgi.ebay.co.uk/Conductive-Shielding-Paint-Guitar-Shielding_W0QQitemZ310068479161QQcmdZViewItem?hash=item310068479161"]http://cgi.ebay.co.uk/Conductive-Shielding...tem310068479161[/url]

You could get some direct from Stewmac in the US. The Stewmac stuff is Acheson Electrodag 112 - you may be able to source some closer to home.

I think you can get copper adhesive tape cheap enough from garden centres (it's used as a slug repellant around plant pots...). You'll find that you'll pay a premium for stuff from guitar places. Make sure you solder the joins if you go that route.

It may be worth using a multimeter to check how good the conductivity of the job is.

[EBS_freak]

PS - if you do it, take some pictures as a guide for people who may be experiencing similar problems.

[Weird War]

Funnily enough, I've been thinking of doing just this to my MIJ 75RI Jazz - going to take a look at its innards tonight first. The brush-on shielding paint looks straightforward.

[EBS_freak]

[quote name='Weird War' post='249770' date='Jul 28 2008, 04:48 PM']Funnily enough, I've been thinking of doing just this to my MIJ 75RI Jazz - going to take a look at its innards tonight first. The brush-on shielding paint looks straightforward.[/quote]

Yup - it's pretty straightforward - especially with the paint. It's amazing how much the things start to quieten down with a bit of decent cable, a decent earth and some screened cavities.

I'm surprised that a MIJ has no screening... did you manage to take a look inside?

[Weird War]

[quote name='EBS_freak' post='250321' date='Jul 29 2008, 11:45 AM']Yup - it's pretty straightforward - especially with the paint. It's amazing how much the things start to quieten down with a bit of decent cable, a decent earth and some screened cavities.

I'm surprised that a MIJ has no screening... did you manage to take a look inside?[/quote]

Aye, had a look last night. The only screening was a piece of copper at the bottom of the control cavity; nothing in the pickup cavities (as I expected).

[EBS_freak]

[quote name='Weird War' post='250402' date='Jul 29 2008, 01:13 PM']Aye, had a look last night. The only screening was a piece of copper at the bottom of the control cavity; nothing in the pickup cavities (as I expected).[/quote]

Yeah - best to screen the side of the cavities also. If you do anything, let us know how you get on.

[Weird War]

Well, as I haven't got a gig for a month, I decided to try shielding my 75RI Jazz.

Tonight, using copper tape with adhesive backing, I've shielded the pickup and control cavities. I did this without disconnecting any wiring, and just worked around as best I could. I think I've done a fairly neat job so far, though I had to use a few small bits in awkward gaps. The adhesive tape is supposed to be conductive, but it seems best to tack solder the joins between the pieces of copper tape - a job for tomorrow night.

Questions:

1. What should I do about the 'tunnels' between the pickup cavities and control cavity? Am I right in thinking that the shielding has to be 'continuous' (i.e. joined up and showing no resistance) in order to work?

2. The scratchplate is plastic - should I do anything to it?

3. Would you recommend changing the existing (standard) wiring and grounding (as suggested by Lyle Caldwell on TB)? I'm ok at soldering but don't mind a lazy option now and then.

Thanks for your help, I'll keep you posted. (Apologies for lack of photos - new camera arrives tomorrow!).

Cheers

Doug

[BOD2]

Bearing in mind that the pickups themselves are not humbucking and can therefore be a source of noise, there comes a point where you can go too far with the shielding !

Also, there seems to be quite a lot of "try it and see" to the mystic art of shielding.

It's usually the control cavity that is shielded most. It won't do any harm to line the wiring tunnels to the pickups but it might not make any difference either.

Yes - the shielding has to be continuous and has to be grounded at some point also. The object of shielding is to create an earthed "metal box" around the electronics - any incoming electrical interference will hit the "metal box" first and be dissipated to earth before reaching the electronics.

Often the underside of the scratchplate (at least around the control cavity area) is lined with foil - creating a lid fo rteh "metal box". The foil in the cavity itslef if overlapped onto the body so that when the scratchplate is screwed down both foils touch and close the "metal box".

There is an earthing arrangement called "Star grounding" (info here [url="http://www.guitarnuts.com/wiring/shielding/bass.php"]http://www.guitarnuts.com/wiring/shielding/bass.php[/url] )
in which all earths are connected to a single common point rather than the mish mash of earths and earth loops on most Fenders. I would try shielding first and see how quiet that makes things.

[Weird War]

Hi BOD2

Thanks for your thoughts. I've now shielded the pickup and control cavities with copper foil:




but have yet to alter any wiring (such as grounding everything at one place). As you can see, in each cavity there is the Fender copper grounding plate which is now sitting on my foil shielding.

I normally use my EBS Microbass with headphones to test things, but for some reason, it's not working with perfectly good 9V batteries. When powered with a Diago, the Microbass is noisier than when battery-powered, so I can't really tell if shielding has helped just now. I will test with my practice combo at reasonable volume tonight too.

Cheers

Doug

[dub]

It sounds like you are having some trouble with ground loops if the microbass is noisy. You could use an extension cable with the ground lifted to plug in your power supply, but make sure the amp is still earthed. Write "earth disconnected" on the extension so it doesn't get used for anything else that could be dangerous.

Do the new pickups sound better?


[quote name='Weird War' post='267047' date='Aug 21 2008, 01:42 PM']Hi BOD2

Thanks for your thoughts. I've now shielded the pickup and control cavities with copper foil:




but have yet to alter any wiring (such as grounding everything at one place). As you can see, in each cavity there is the Fender copper grounding plate which is now sitting on my foil shielding.

I normally use my EBS Microbass with headphones to test things, but for some reason, it's not working with perfectly good 9V batteries. When powered with a Diago, the Microbass is noisier than when battery-powered, so I can't really tell if shielding has helped just now. I will test with my practice combo at reasonable volume tonight too.

Cheers

Doug[/quote]