Squier VM P-bass hum/buzz

[LennyPenny]

Hi all,

About two weeks ago I bought a secondhand Squier VM P-bass. Today was the first time I used it for band rehearsal and there was quite a bit of buzz. I use a Zoom B3 straight into the PA with only an amp model and compression. I never had this issue with my other bass. Also, practising at home through my amp or Korg Pandora Mini, I never had any problems. It's not so much a hum, I know what single coil hum sounds like and it's not like that, more like a buzz. The weird thing is that it goes away if I turn down the tone knob. I tried adding a noise suppressor and that got rid of the noise while not playing, but whenever I play it's immediately there. I also tried the ground lift but that didn't change anything.

The previous owner did swap out the pots for CTS pots. I don't know if he did it himself, maybe that's where the problem lies. As far as I know, split pickups aren't even supposed to buzz so it's got me a bit concerned. The fact that the tone knob affects the buzzing leads me to suspect that it may be a loose connection somewhere.

There are a lot of fluorescent lights and it's a low ceiling so I guess they're causing it. When I squated down to adjust my B3, the buzzing completely stopped.

I'm trying to give as much information as I can to help narrow down the list of possible causes, I don't know if all of it is relevant.

Any help/suggestions would be greatly appreciated!

 

[BlueTalon]

Here's another thread that discusses that question. Bottom line, I think your instincts are correct regarding the fluorescent lights. A good shielding/grounding job should help with most of the noise, if not all of it. There are various methods -- I prefer copper tape, and I explain what I do in the thread link.

 

[megafiddle]

I would make sure that all the existing shielding is grounded properly
before adding any new shielding. If there is an aluminum foil on the
inside of the pickguard, make sure it is grounded. If the cavities are
coated with shielding paint, make sure that there is a connection made
somehow to the paint, usually a screw and solder lug terminal.

Look for the simple solutions first. Many will simply add extensive shielding,
and of course it works. But if the problem was a missing shield ground connection,
it could have been solved much more simply.

-

 

[LennyPenny]

I took off the pickguard to see if there was something obviously wrong and noticed that the ground to the bridge is not connected. At least that's what I think it is, the loose black wire that goes in where the red arrow is pointing (first picture). I supposed this isn't the way it's supposed to be and that this is what's making the buzz worse than it should be, so is there a way to fix this without soldering? I don't own a soldering iron and have never use one.

If there are any other visible issues in the pictures, please let me know, I don't know anything about the wiring aspect of my instruments.

EDIT: right, so I just read that the ground wire from the bridge shouldn't go anywhere, but is it supposed to be loose like that? What if it touches some part of the electronics, couldn't that cause problems?

 

[BlueTalon]

I took off the pickguard to see if there was something obviously wrong and noticed that the ground to the bridge is not connected. At least that's what I think it is, the loose black wire that goes in where the red arrow is pointing (first picture). I supposed this isn't the way it's supposed to be and that this is what's making the buzz worse than it should be, so is there a way to fix this without soldering? I don't own a soldering iron and have never use one.

If there are any other visible issues in the pictures, please let me know, I don't know anything about the wiring aspect of my instruments.

EDIT: right, so I just read that the ground wire from the bridge shouldn't go anywhere, but is it supposed to be loose like that? What if it touches some part of the electronics, couldn't that cause problems?

First, I don't know where you read that the bridge ground wire is not supposed to go anywhere, but that is incorrect. The bridge ground wire needs to go to ground.

Normally, connecting that bridge to ground involves soldering, but you might be able to get away without it if you really want to avoid it. You have a ground lug screwed into your bass about an inch away from the pickup. You can bare the end of the bridge ground wire, crimp a terminal on the end of it, and then attach it with the same screw that holds the other ground wire. Or you can even just loosen the screw, wrap the bare wire around it, and tighten the screw again, but that is an awfully cheezy fix.

You really need to get a soldering iron and get used to using it. And while you're at it, get yourself a multimeter, too, so you can check for resistance and continuity.

 

[LennyPenny]

I know, I'd really like to know how to solder but atm I don't have an adequate space to do so. I assume a kitchen table isn't appropriate.. It's actually a dream of mine to have my own workshop and be able to fix any guitar related issues myself, like pickup replacements and stuff like that.

I'm confused though, in this diagram the bridge ground is connected to the volume pot.
Invalid Link Removed

There are others that show the same thing, in some cases it's connected to the tone pot.

 

[BlueTalon]

Kitchen tables are great for this kind of stuff, perfectly adequate. Of course, if you want to eat there, or have other people in the house who will pester you, you have to be able to move it -- but for doing the actual work on a bass, no problem.

Soldering irons aren't that expensive, get one that's at least 40W, and then start practicing stuff like soldering wires together, soldering wire to a piece of copper tape, stuff like that. You'll get the hang of it, and then you'll feel comfortable enough to work on your bass. Radio Shack, ebay, google search, and you'll find some deals.

There are several schools of thought about how best to ground a bass. Some would say if it's all grounded, it's all good (doesn't matter where or how). Some would say all grounds should ideally be grounded to the same spot ("star" ground). I'm sure there are other variants as well, but my preference is to keep bridge+shield ground and signal ground isolated until they connect at the jack. In your case, that might not be possible, but given the choice to ground your bridge to the shield or ground it to the signal chain, I would ground it to the shield.

Oh, one other advantage to doing it that way is this -- if you have to remove your control plate for any reason, having the bridge wire grounded to the grounding lug in the body cavity is a helluva lot more convenient than having it connected to a pot. You can move the control plate off to the side easier without the bridge wire limiting your range of motion.

Don't worry about the picture. You can find a lot of different pictures on the web, showing the same thing done in different ways.