Model Js buzz like heck! Now fixed, I think.

[Martin Tenbones]

Hello everyone!

Long time lurker, and I hope i offend no one with this, my first thread.
I just put Dimarzio Model Js in my 2012 MIM Jazz.

When both of the vol pots are at less than 100% there is a crazy buzz, not just the hum like with single coils.

I have searched and searched and can't find an answer.

Here is my current wiring...

MIM Model J wiring problem?

• Martin Tenbones
• Mar 12, 2015

VOL POT 1 has red wire from neck pup on centre pole, with pup ground (green) and ground wire (black) running to shielding.

VOL POT 2 has red wire from bridge pup on centre pole, and pup ground (green) via shielding screw.

TONE POT has ground wire to bridge.

There is no ground attached to output jack.


Thanks for reading, and thoughts?

To elaborate, the pickups sound great with both, or either one of the volumes at full.
If one is 80% and the other 50% (for example) , there is a massive buzz that renders the sound useless.
This buzz also goes away if the tone is at 0%.

 

[walterw]

Here is my current wiring...
VOL POT 1 has red wire from neck pup on centre pole, with pup ground (green) and ground wire (black) running to shielding.

you mean the black wire from the pickup?

if so, that's completely wrong, and not what the dimarzio directions say!

 

[Martin Tenbones]

Sorry to be unclear, the black wire attached to VOL 1 is the previously existing ground wire to the neck pup cavity.

The black and white wire from each pup are soldered to each other, in pairs, as instructed.

 

[xOriginalNinjax]

I'm guessing the bridge ground is running to the tone pot?

I would retry the grounds on the back of the pots, maybe try linking your grounds as well, from jack to tone to both volumes. Could be that your plate isn't grounding how you need.

 

[Martin Tenbones]

Yep bridge ground runs to tone. I will redo the grounds.

Should I have a separate ground wire to bridge pup cavity? Or can I keep it as is with the bridge pup ground wire connecting to the cavity, then on to VOL pot 2?

 

[xOriginalNinjax]

You should have any existing grounding wires running from them to the closest pot (neck pickup cavity wire to neck pot, bridge pickup CAVITY wire to bridge volume pot, and actual bridge ground wire to the tone pot or output jack).
If I have a bass that has hum, I link everything together as well to ensure that my grounds are all connected properly.

 

[RobbieK]

Did you buy these pickups new or second hand? The model J's and P's are well known to occasionally lose a magnet. If some one reglues the magnet in the wrong orientation, there's a chance they won't hum-cancel properly. But It would be pretty unlikely this is the problem from the way you've described it.

Also, I'd add an earth wire to the jack for sure. (Also probably not the problem, but it should be there.)

The black and white wire from each pup are soldered to each other, in pairs, as instructed.

You insulated this join, right?

the pickups sound great with both, or either one of the volumes at full.

So with say, 100% and 50%, there's no buzz, right? But suddenly there's buzz if you go 99% and 50%. Right?
If so, then I'd test the pots.

 

[RobbieK]

my first thread

PS: Hello and welcome!

 

[Martin Tenbones]

The pickups are brand new, and as I said, sound great unless one of the VOLs isn't at 100%. Or the TONE at 0%.

Will redo the grounding right now.

And Im unsure how to test the pots, but yes RobbieK that is correct, and the buzz at 99% and 50% would disappear if i put the TONE at 0%. But they worked perfectly with the stock pups.

And thanks for the welcome. I've been reading this forum for years.

 

[Martin Tenbones]

***. I just plugged it in to my amp using my usual (better quality) cable. No buzz.

SO, what the hell?

Maybe I should quietly accept this and move on…

Could any grounding problem that exists be revealed by using a cheap cable, but disappear with a quality one?

 

[xOriginalNinjax]

Not necessarily a grounding problem, most likely an interference problem.
Cheap cables are typically poorly (or not) shielded, and thus you'll hear all sorts of things you normally wouldn't.

 

[walterw]

Sorry to be unclear, the black wire attached to VOL 1 is the previously existing ground wire to the neck pup cavity.

The black and white wire from each pup are soldered to each other, in pairs, as instructed.

OK, sounds like something else is going on then.

do you still have any wires going to the body cavity walls attached? they need to be there to ground the shielding paint.

 

[Martin Tenbones]

Yep those are attached. The DiMarzio dude suggested a grounding layout that I will try in a few days, after I get some copper tape to improve the shielding.

 

[walterw]

Yep those are attached. The DiMarzio dude suggested a grounding layout that I will try in a few days, after I get some copper tape to improve the shielding.

if there are screws going into the wood, then you already have shielding in there, and there's no point in the copper.

also, there's no point in any kind of special grounding "pattern", in a guitar stuff is either all grounded or it isn't.

"star grounding" and all that has no purpose in a guitar, where there's only one ground potential, the sleeve of the cable.

i suspect something way more obvious, like a missed connection, bad solder joint or a bad cable. do you have a multimeter you can use to actually check all the ground connections, including from the bridge itself?

one thing, you're relying on the metal plate itself to make the ground connection between the pots and the jack; it might be worth it to run actual soldered ground wires connecting those 4 components, so that the sound doesn't fail if one happens to get loose.

 

[RobbieK]

***. I just plugged it in to my amp using my usual (better quality) cable. No buzz.

SO, what the hell?

Friday the 13th dude.

 

[BlueTalon]

Yep those are attached. The DiMarzio dude suggested a grounding layout that I will try in a few days, after I get some copper tape to improve the shielding.

Here are a couple of sources for copper tape on ebay. Get ten times the tape for half the price of buying it from some other places.

These sources are in the United States, too. They're probably just a front for Chinese sources, but the fact that they're located in the U.S. means they'll get to you a lot quicker.