Sheilding/wiring help for newbie

[john50]

Posted this already with a dumb title that isn't getting enough attention. I have to sort this out by the weekend if anyone can help

Hi - I've just spent my time 'Quieting the Beast' - following the instructions on Guitar Nuts, using a telecaster with a pre-wired four position switch and a strat with a TBX tone pot and an aluminium scratchplate. Both are equipped with Fralin pickups.

My problem is that the wiring on the tele is causing the whole bridge (and consequently the body) to be microphonic and the guitar whistles and squeals when using that pickup - especially with distortion. The same is happening to the strat on all pickups! The strat pups worked fine without the shielding or ali plate.

What could be wrong? I don't want to start stripping it all out if there is a simpler solution.

Please help!

Thanks in advance, John

[ashcatlt]

first thing i'd check is the polarity of the output jack. that is, do you have the ground and hot backwards?

[john50]

Thanks for replying ash - I've checked them and it all seems right.

Any other ideas?

[michaelcbell]

It is possible that after "quieting the beast" you've simply turned your amp up louder (to a similar noise level, but since there's less noise now...) and that is causing your feedback issues?

[sumgai]

john,

First, sorry for the seeming "ignoring" of your earlier question.

Your description points out a couple of things. One, inserting/installing a shielding system can't make one or more pickups suddenly go microphonic (the tech term for the symptoms you described). My gut instinct is to say that the pickups are not mounted correctly, in both instances.

On the Tele, the bridge plate is mounted hard and fast to the body, so the screws are all tight, right? And the pickup itself is positioned properly under the strings, not too close, not too deeply recessed into the body cavity, right? Then it comes down to the pickup itself being either stuck catty-whampus in the bridge plate (it's making unwanted contact with the plate), or else it is just plain microphonic in nature, and when you re-assembled everything correctly, you "undid the factory adjustments" that prevented the microphonics from sounding out.

(Second thoughts.....) Is this a factory pup, or aftermarket? Did you leave off any base plate(s) that may have been present at the outset?

Almost the same for the Strat. In this case, if all the pickups are microphonic, then it's either the way installed them into the pickguard, or the p'guard itself is mounted loosely, and is vibrating in sympathy with the body, thus creating a feedback loop.

Also just some thoughts, like michael's above. ;D

HTH


sumgai

[john50]

Sorry to say guys that none of the above applies. The amp is the same as always. All screws are tight.

This is my first tele so I don't know if the bridge plate is meant to be part of the bridge pickup in terms of being slightly microphonic but if you tap the bridge its definitely like tapping a quieter pole piece. This is a ringing guitar in that its a one piece swamp ash with just danish oil on the body and the bridge is a Callaham cold-rolled steel job with stainless steel saddles. Both rigs are using factory Lindy Fralin pickups. I have added a base plate on the strat bridge pup but all the pup positions are causing this microphonic feedback and seeing that they weren't with a plastic scratchplate and the only difference is the ali scratchplate and the shielding. The other strat I've shielded with plastic scratchplate is fine. I thought an ali scratchplate would provide better shielding.

My new question is should the metal of the scratchplate (strat) be touching the copper shielding overlap? I know that the pictures for the tele show this - but does anyone think that this might not be right for the strat - or is it simply that ali scratchplate?

[sumgai]

John,

Short answers:

It's OK for the aluminum pickguard to touch the cavity's copper shielding, in fact it's desirable - from the standpoint of shielding itself, we don't want any gaps in the coverage. However, there are some issues over the long term, but they don't apply here, so let's drop that until we get the microphonics problem cured.

(Forgive me, but your post seems to mix things up, going back and forth between the two guitars. If I've said something below that is totally wrong, sorry for the confusion. )

I wouldn't think that the metal pickguard could be the problem, but then again, there's only way to truly find out for sure - swap everything back to the plastic jobbie, and test again. Much effort, but with guaranteed results.

For your Tele, using a Fralin pickup (generally regarded as good) with a Callaham bridgeplate (also has a good reputation) should not be the direct cause of your problem. The question becomes, why did you install a base plate? Did it come with the Fralin? Is it optional, or required?

And finally, have you inquired of Fralin if there are known problems of this type, either in conjuction with a Callaham bridgeplate, or just in general?

Sorry I can't be more specific, this is one of those times where "remote diagnosis" isn't easy!

HTH


sumgai

[john50]

Thanks sumgai for your support on this - I'm sorry I've been a bit confusing. To clarify; I haven't added a base plate to tele bridge pup - only to strat bridge pup.

Will try all recommendations and get back if problems persist.

Thanks again,
John

[sumgai]

John,

Hell, get back to us even if the problems don't persist..... we wanna know that you fixed them, and how you did it! ;D

Good luck!


sumgai