Seymour Duncan SMB-4D hums when in series

[guest22338668]

Hi folks, I've got this problem for a while and it's killing me...

So I'm using a smb-4d on my OLP MM with a preamp and a parallel/series switch. In parallel, the bass sounds just fine but when I put the pickup in series the bass just hums as hell.
I've seen this thread http://www.talkbass.com/threads/series-parallel-hum.697683/
and I think I've got the same problem with my pickup, altough mine has a shielding wire on it.
Also I believe that my wiring it's properly done, and without grounding issues.
So what should I do? Remove the pickup and check the wiring? Have I got to open the pickup up? Thanks for answering.

 

[mmbongo]

Check the wiring, it sounds like you have it wired for single coil instead of series. Tap on each of the coils with a screwdriver to see if they are both working when you are in series mode.

 

[guest22338668]

Check the wiring, it sounds like you have it wired for single coil instead of series. Tap on each of the coils with a screwdriver to see if they are both working when you are in series mode.

Yes, it is in series and hums a lot. I'm going to have to remove the pickup, right?

 

[mmbongo]

Yes, it is in series and hums a lot. I'm going to have to remove the pickup, right?

No, just tap on the pole pieces and make sure both sides are working. If it's truly in series, both sides will work and you will have no hum. It will also be almost twice as much output as parallel mode.

 

[guest22338668]

No, just tap on the pole pieces and make sure both sides are working. If it's truly in series, both sides will work and you will have no hum. It will also be almost twice as much output as parallel mode.

I'm sorry, but I think you didn't understand my problem. When I put the switch in series, both sides of the pickup work and it's louder and with less treble and more low mids. The pickup works indeed in series but has lots of hum, that's the problem.

 

[mmbongo]

I'm sorry, but I think you didn't understand my problem. When I put the switch in series, both sides of the pickup work and it's louder and with less treble and more low mids. The pickup works indeed in series but has lots of hum, that's the problem.

Yeah if you've already verfied that both sides are working then I'm not sure. Odd that you'd have hum in series and not parallel. Maybe try to hardwire it in series by not using the switch at all and see if the hum goes away.

 

[guest22338668]

So I've been messing around with my multimeter and I found that the green wire (front coil ground wire) and the front pole pieces are "conected", it beeps when I touch both with my multimeter, although it doesn't happen with the other coil. Also when connected to the amp, touching the front pole pieces injects hum into the sound, touching the back ones cancels hum. Is this the source of my problem or is it normal?