Dimarzio Model J's: E and A not working? Help!

incognito89x · #1 05-25-2007, 06:28 PM

Ok, so I just installed a set of Dimarzio Model J's in my Spector.

The Bridge pickup is working fine, but the neck pickup, only the D and G strings are getting any juice. The E and A are just barely audible at full volume.

What could be causing the problem here? Thanks in advance for any help.

luknfur · #2 05-26-2007, 02:31 AM

FWIW:

split HB so incorrect wiring in all probability cause one coil's not doing anything of consequence. DM has diagrams on their site. If you've installed a switch, that's probably the source.

Been a post on this within the last couple weeks.

incognito89x · #3 05-26-2007, 01:23 PM

I didn't install a switch. Just the basic job. Red to the middle leg, green to the pot, white and black together.

Should i just resolder to make sure I didn't mess up there?

Chris Breese · #4 05-26-2007, 02:29 PM

Yes. Try re-soldering...

luknfur · #5 05-26-2007, 05:46 PM

Quote:

Originally Posted by incognito89x

I didn't install a switch. Just the basic job. Red to the middle leg, green to the pot, white and black together.

Should i just resolder to make sure I didn't mess up there?

FWIW:

no clue how you wired it. Sounds out of phase but no small feat to wire 1/4 of the coils out of phase, 1/2 is eaiser done than said. Using a blend? If so likely miswired.

You could also stick a meter on that run amuck coil and verify it even works. That would be the first thing to do.

incognito89x · #6 05-26-2007, 06:18 PM

I'm running an Aguilar OBP-1 preamp; VOL - VOL - TREB - BASS

Quote:

WIRING THE PICKUPS
Solder the red wire of each pickup to leg #2 of its respective volume
pot. Solder the green wire of each pickup to the back of its respective
volume pot. Solder the black and white wire of each pickup together.
Put a piece of tape on this connection so that it does not touch any other part of the circuit. The wiring is now complete.

That's the wiring instructions I followed.

luknfur · #7 05-27-2007, 01:30 AM

FWIW:

swap the red and green on one volume control and see what you get.

bgavin · #8 05-27-2007, 09:36 AM

Quote:

Originally Posted by incognito89x

I didn't install a switch. Just the basic job. Red to the middle leg, green to the pot, white and black together.

This is series wiring. Just like Christmas tree lights, if either one is out, the string goes dead.

Since the other half of the pickup is working, this tells me there is no open wire in the E-A group.

incognito89x · #9 05-27-2007, 11:29 AM

Quote:

Originally Posted by bgavin

This is series wiring. Just like Christmas tree lights, if either one is out, the string goes dead.

Since the other half of the pickup is working, this tells me there is no open wire in the E-A group.

Meaning... the pickup itself is broken? Or just my attempt at wiring the pickup was only half successful and I need to do it again?

saxofunk · #10 05-27-2007, 06:58 PM

No wires, no switches, and you can fix them yourself. It's the magnets. I had the same trouble with a set I bought used, the crusty glue didn't secure the magnets during shipping.

Get a magnet off your refrigerator for reference (or better yet, a magnet with marked poles or one of those fancy StewMac pole polarity testing magnets)... A standard flat round magnet will wiggle one way or the other when held over a pole piece. Take the magnets off under the effected strings, put them on in various positions until you get indentical polarity under the E-A side and the D-G side. Once you get them all line up, re-install, test, uninstall, hot glue it all back together, and install it once and for all. PS - the bridge pickup should have opposite polarity of the neck pickup.

incognito89x · #11 05-27-2007, 08:00 PM

Update:

I've gotten the E and A working. It appears to have something to do with the pickup height.

I took the pickup out to make sure it was physically ok. After putting it back in, I had the E and A strings working. While configuring the pickup height I lost the E and A strings again (I should specify that they were just barely audible the whole time, but really not "working".) After noticing the E and A dropping out again, I raised the pickup back up and the E and A starting working as normal again.

Could I be putting too much pressure on a wire when the pickups are lowered, and that's cutting out the E/A volume somehow?

luknfur · #12 05-27-2007, 11:34 PM

There's your answer then, raise them to where your satisfied with the output. Adjusting pup height is a routine part of the installation process. Doubling the distance from the strings drops output by about 60%.

For output to have been that lop-sided, that pup should have been slanted like a ski slope so the fix obvious - unless something else is amiss.

incognito89x · #13 05-28-2007, 12:05 AM

I suppose it's possible, but it didn't seem noticeably lopsided. IN any sense thanks for your help luknfur and the rest

Appreciate it.

While I've got the thread here:

During the pickup swapping, I noticed that there was no shielding at all in the bass. (In the pickup cavities). I've seen a lot of pics that have the copper shielding tape within the pickup cavities. I do notice a hum on my bass when I'm not touching anything metal on it (strings, tuners, etc).

I'm assuming it would probably be a good idea to get some shielding tape and put some in the pickup cavities?

luknfur · #14 05-28-2007, 12:17 AM

FWIW:

most basses do not have foil shielding but shielded paint. Foil shielding may reduce it but it may not but it's not a fun project and may create other problems (is great stuff for shorting hot leads for starters).

I've foil shielded a few basses and I personally would never do another short of a last resort. Didn't help any I could tell.