Pickup tape gunk removal

[stinkfeet]

I just got a Dimarzio D Activator for a great price because the owner was having trouble getting a full reading. It seems like the owner must've messed with it since it first got listed, because it didn't read at all when I first got it. I've gotten the higher wind coil to read 5.8k now, but I'm having trouble getting anything out of the second coil. When I took the tape off of it, it left a bunch of residue and I can hardly see if there's a snapped wire somewhere. Does anyone have any tips for getting rid of the gunk? I tried rubbing alcohol with Q-tips, but that didn't get me much success. I have some contact cleaner I could try, but I don't know if it'll take the coating off the windings.

 

[jeremy]

man, that is a lot of gunk. i dont have a god suggestion other than be careful

 

[stinkfeet]

On the lower wind bobbin, I was able to get a good bit off with some Q-tips and the contact cleaner, but the edges of the bobbin are still pretty gunky. I don't know what would be a good thing to use to scrub softly in the corners since the Q-tips can't get in there.

I can't see any visible breaks yet, and I still get no DCR or continuity. It does read about 4.7nF on my Fluke, or 3nF on my cheapie LCR, which is about the same as the good coil. So maybe it's good? I might put it back together tomorrow and see if it makes noise or picks up anything on the funky coil.

 

[freefrog]

I know it will sound a bit savage but... I'd try to put it in boiling water.

I've done that more than once in desparate cases and it worked: the tape unglued by itself then wax melted and mounted at the surface of the pot, giving access to the first peripherical layers of wire.

Tongue in cheek NOTE - I'd not recommend to do the same thing without knowing the kind of plastic used for bobbins and with overheating wax instead of water.

https://theguitarlearner.com/2014/08/16/and-i-destroyed-my-guitar-pickups-fail-html/

 

[freefrog]

I still get no DCR or continuity. It does read about 4.7nF on my Fluke, or 3nF on my cheapie LCR, which is about the same as the good coil. So maybe it's good? I might put it back together tomorrow and see if it makes noise or picks up anything on the funky coil.

No DCR (or extremely high DCR) + capacitance reading is generally indicative of a broken wire: the two ends remain aligned with each other and the small gap between them, still encapsulated in wax or linked by a super thin bridge of insulating varnish, changes the section of broken wire in a capacitor...
Incidentally, 4.7nF is really a typical measurements in such cases. ;-)
It might work but should sound just like an intact coil in series with a 4.7nF cap: thin and trebly. Now, there's a use for such coils (scroll down to post 8 if you want to see what a capacitive broken wire does to the raw electrical response of a humbucker):

https://marshallforum.com/threads/t...nd-records-without-anyone-noticing-it.130785/

:-D

 

[stinkfeet]

Thanks so much for all the good information!

That makes a lot of sense. I saw someone who had a similar problem, and they made it sound like it was doing the same thing that happened to Van Halen's JB.

I'm a little afraid of putting it in boiling water, but it seems like it's what I'll have to do. The coil is pretty clean now, but still has no visible breaks. The good coil no longer reads a capacitance, but the bad one does still.

 

[hamerfan]

I tried the ‚boiling water‘ approach one time with success. But mind at 100 C the plastics get soft, but you need more than 70 C to get the gunk out. In my case i was boiling the water and put tea thermometer in it to check the temperatur. After it got lower than 90 C i put the pickup in. Worked.