Weird pickup problem

[Philly Q]

Today I was testing out some different combinations of Tele pickups (no BKPs, I'm afraid  :oops: ), using my old Frankenstein Squier Strat with a scratchplate cut for Tele pickups.

One of the pickups I tried is a DiMarzio Virtual Hot T - a stacked humcancelling pickup which is supposed to be quite high output.  In the guitar, it sounded incredibly weak, and also seemed prone to hum.  I thought only one coil might be working, but the black & white wires seem firmly soldered together.

Then I noticed that the hum is worse when I pick a note - it's quiet when the strings aren't ringing, but when I pick I get a puny little note and a load of hum.  It's almost like there's a noise gate on it.

Any ideas what could be wrong?

[Henk]

http://www.dimarzio.com//media/diagrams/DP413_install.pdf

Sounds like you put the hot to the ground in some way. Green and bare go to ground and red is hot and black and white together for both coil mode i gather after a quick read. It could be the pickup is dead though, happens.....  :(

[Philly Q]

Green and bare go to ground and red is hot and black and white together for both coil mode i gather after a quick read. It could be the pickup is dead though, happens.....  :(

That's how I wired it - double and triple checked the connections too.  I know those colour codes by heart, I've had lots of DiMarzios over the years.

I guess there's something broken internally.  It's a "new" pickup, but I've had it a long time so I guess it's out of warranty.  Oh well, I might carefully take it apart and have a look later.  I suppose I could check it out with the multimeter too.

[WezV]

yeah - get the multimeter out  and check what its reading  on each coil first

[Philly Q]

Well, that was interesting - the pickup's DC resistance is just under 2K!  :lol:  It's supposed to be 9.34K.

If I measure from the coil split to the green wire, it's 2K again.  From the coil split to the red wire gives a big fat zero.  So I guess I was hearing the bottom coil, which is really only there for hum-cancelling.

So does that mean there's a break in the top coil somewhere?  I suppose it might just be that the red (or black) wire isn't connected properly.

[WezV]

tis a dud.  

If you get lucky it might just be a break near the lead wires.  Obviously if its a break deeper in the coil then its a real problem.  could always just get tim to rewind it

[Philly Q]

could always just get tim to rewind it

I know he's not a fan of stacked pickups.  He might put a curse on me.  :(  :lol:

[Henk]

It could be the one of the wires is in connection with the ground, which would give you a very small resistance since the current isnt passing trough the coil.

Was the pickup detached? Did you measure red to black and green to white?

Anyway i know too little about these things to know what it could be, im just guessing along with you :oops:

[Philly Q]

Was the pickup detached? Did you measure red to black and green to white?

Yes, and yes.  There's no reading at all between red and black.

I just took the tape off the pickup, but there's no way of getting to the points where the coloured wires connect to the coils without dismantling the whole thing.  And since it's obviously been wax potted after assembly, I don't feel up to going any further at the moment.  :(

Oh well, it's not the end of the world, I've got other Tele pickups.  I might see if Tim will have a look at it at a later date.  I might even ask if he can put a proper fibreboard top on it so it doesn't look so bloody ugly.