Oil City Pickups ... Microphonic DiMarzio

OilCityPickupsOilCityPickups Frets: 9982
edited July 2017 in Made in the UK tFB Trader
A quickie here: 
As you guys know, I have a soft spot for 'classic era' DiMarzios ... and the other day a customer brought in a guitar with a pair of 'PAFs'. They kicked out a nice sound ... what you could use of it ... because they were probably the among most microphonic pickups I've ever tried! Something very wrong there. These pickups are early eighties by my reckoning, triangular feet are usually the 'tell' here. 
The end view shows pretty standard stuff for any 'PAF' style pickup ... it's when you take out some pole screws that you can see why the microphonic bit is running riot.

The pole screws were incredibly loose ... as in not even needing a screwdriver to remove them ... just put your finger on top of the screw head and rotate!!! That'll be the reason for the squeal and nasty noises then. 
The reason for the loose pole pieces is one of those quirks of DiMarzio construction ... although the PAF appears to have normal Gibson style bobbins ... that is, one slug bobbin and one screw bobbin ... in fact both of these are slug bobbins! The reason for this was probably cost cutting: all DiMarzios other pickups at the time had hexagonal screw slugs on both bobbins (like the Super Distortion) and so used two slug bobbins for each pickup. So if you could get away with it, why not use the same setup for a PAF ... just drill and tap the standard brass baseplate, and have the narrow thread of the screw pole running in an oversized 'tunnel of nothing' ... rather than being threaded into the bobbin as normal with Gibson etc.

If you look down the screw pole holes here ... what you are looking at in the bottom of the hole in the top of the keeper bar (and not even the steel keeper bar was threaded ... just the thin. soft brass baseplate!) Now this setup probably worked fine when the pickup was new ... the plastic gripped the sides of the slot headed  pole screws tightly, and everything was good ...
Fast forward three decades and multiple pole screw adjustments and wear and tear ... and hey presto ... super loose pole screws.
The customer had asked me to pot these for higher volume use ... which I did ... but a simple solution that you can try at home if your old DiMarzio PAFs goes microphonic ... is some clear nail polish around the junction of each of the pole screw where they emerge from the back of the baseplate. This doesn't always work as other components may be loose as well ... but it's worth a try.
Professional pickup winder, horse-testpilot and recovering Chocolate Hobnob addict.
Formerly TheGuitarWeasel ... Oil City Pickups  ... Oil City Blog 7 String.org profile and message  

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