mini Humbucker buzz

[fire]

Hi, I just re-wired a 1962 Silvertone 1446 hollowbody guitar for a customer. These guitars came original with a Gibson 2 mini-humbuckers (G-19?). The guitar came to me with a loud high freq buzz that when touching the pickups, 3 way switch, or pot shafts, went away. Touching the strings or Bigsby had no effect because they were not grounded. (I tried grounding the Bigsby but to no effect) I do not think these guitars had a bridge to ground.

Upon further inspection, I noticed the inner insulation on the braided pickup wire leads was crumbing into powder. I though A-Hah! This must be the problem. So I re-wired the pickup leads from the inside of the pickups out. I also re-wired the entire guitar with new pots, caps, output jack, wire. I had to use the old 3 way switch because a Gibson style would not fit. The old one looked fine, so I just re-wired it. STILL had the same buzz as it did. So I sheilded the backs of the pickups with copper foil. Still the same. hhhmmm.... The only thing else I can think of is the fact that I used standard 22guage insulated wire instead of the braided sheild wire? Or the 3 way switch is the problem? the pickups tested fine. 7.58K on both neck and bridge. I tested the continuity on the grounds and I tested resistance from the pickup covers to the output jack. It read 0 K ohms
Any ideas? I have searched on many websites/forums that people having a guitar with buzz when the pickups/strings are touched it goes away. But I never found a clear answer or diagnosis strategy for this issue. Maybe you guys can help

Thanks! ~Richard


I have read on many sites people having a guitar with RF buzz when the pickups are touched it goes away. I never found a clear answer or diagnosis strategy for this issue.

[big_teee]

Hi Richard:
It does sound like a ground issue.
Does the insulated wire you used have a grounded shield.
What wire did you use from , pots to the switch.
The switch needs to be bonded to ground also.
If you can't get a handle on it, start isolating things.
Like Napoleon fought wars, Divide and Conquer.
You could break it down all the way to one pickup to the jack.
Or one pickup one pot, to the jack.
I would keep the bridge grounded, in the process, at least until you get your problem solved.
I had a similar deal on a new Les Paul copy.
The ground wire was connected to switch ground, but the ground wire wasn't connected to ground at the back of the volume pot.
When I connected the shield to ground at the pot all noise stopped.
Please let us know what you find.
Wiring Diagram

Good Luck,
Terry

[fire]

big_teee, thanks for the information and the diagram! Ok, the wire I used throughout is typical radioshack 22 gaw with plastic insulation, not the outer metal braid wire. I suppose this might be the issue maybe. Yes the switch is grounded to the Neck vol pot I made sure of that. I wired the guitar like a Les Paul as seen in the Shatten design book of standard wiring on page 31. I can scan it and send it to you if need be. It's different than what you just sent me. On my diagram The caps go between tone and vol pots like on Les Pauls and the grounds go from; vol pot to vol pot, neck vol pot to neck tone pot, and tone pot to tone pot

[FunkyKikuchiyo]

Is all the wiring shielded, or just the leads coming from the pickups? If the controls are jumped together sans shielding that can add a bit. Especially on larger bodies, those wires can run a pretty long length.

How sure are you that it is beyond what it was originally designed for? I mean, there may be nothing "broken", it could just be noisy. I don't know what this particular instrument looks like, but I'd try to find a way to ground the strings. Sometimes you can get at it via an endpin hole. Many Bigsbies will wrap around the back of the guitar and you can get a small wire in there.

I have to confess I've never lifted the ground to the strings just for the sake of experimenting, but in theory it would attract noise if not grounded, as well as just not helping shield. Try this: does touching the strings (but not touching the pickups) noticeably increase the noise, or do absolutely nothing? If it increases, then I think you've found your culprit.

[fire]

Like I mentioned, the entire guitar is wired with the wire I mentioned; standard stranded 22gaw. which is just the wire strands in plastic insulation ie. speaker wire. It does not have the sheilded outer metal braid. This is beyond normal noisy for any instrument. If you google Silvertone 1446 you'll see it. Chris Isak played this model and made it popular. It is a collectable guitar. Anyway, I did try grounding the Bigsby just to se what would happen, as I also mentioned. There was no ground on the original setup. It made no difference unfortunately, and when touching the strings it does nothing..... because they are not grounded to anything. I wrote; " Touching the strings or Bigsby had no effect because they were not grounded". hahaha did you read my post?? ;-)

[big_teee]

Richard:
I read your original post again.
It looks like you have gone through a lot of work already.
You said you rewired the pickups. Without seeing them I presume you had to take off the chrome cover to do that.
Before you rewire with shielded wire, you might try my earlier suggestion and just try one pickup wired to the jack and see what you get and go from there.
Lots of times if you make the circuit real basic you can eliminate the problem and start building it back a step at a time.
If you wire one pickup to the jack and it's quite, you might try the other pickup.
The only problem if it's a hollow body with no rear access, it won't be a fun job probably.
I looked for the page 31 of Schatten book no luck, but I imagine it is similar.
You could wire the circuit a number of ways, for that matter you could leave the tone pots, and caps out of the circuit for now.
Get some sleep and I will be glad to help you tomorrow.
Good luck,
Terry
Hang in there.

[fire]

Terry, I did remove the chrome covers, spliced the wire to new wire, shrink tubed the connection, grounded pickup plate etc. I did everything neat and correct yes. Yes I will try what you said, eliminate everything and go straight to the output jack. I should have done that to begin with. Good thing there is an access panel cut into the back of the guitar with a cover! :-) Or else it would be more of a nightmare than it is. I have spent literally hours on this guitar, never been stumped like this before.

Thank you again for your effort! Very kind
~Richard

[big_teee]

Well the rear panel will sure help.
so you might try this.
take the guitar and plug in the cord.
Or from the ground side of the jack.
You should read continuity from the jack to the rear of each pot, to each pickup cover, and to the 3-way switch.
With the volume pots cranked wide open.
With the cord plugged in, You should read continuity from the tip of the cord to what ever pickup selected and 1/2 that when the selector switch is in the middle with both selected.
Try that if you want to.

[fire]

Hi Terry, I'm going to try that now. Speaking of buzz and RF noise, Have you read the following info on guitarnuts website:

"The noise (usually) gets quieter when a person touches their guitar strings because the strings are grounding the player! Almost all guitars have a wire that connects the bridge (or tremelo claw) to the ground terminal of the output jack so that the strings are gounded. When someone picks up the guitar and holds it close to them, that person's body is acting as a radiator or reflector of noise in the vicinity, "concentrating" it, if you will, close to the guitar's pickups.&nbps; Then, when they touch the strings their body is suddenly much better grounded, shunting noise to ground. They go from being a radiator or reflector to being a shield. How much the noise is reduced depends on the person's internal and skin resistance – a person with high resistance may still be concentrating a bit of noise around the pickups while a person of low resistance may completely shunt the noise to ground.
If the strings are not grounded, the noise will usually actually get louder when someone touches the strings because the strings act like very good radiators to concentrate the noise from the person's body right over the pickups. If the player's body was grounding the strings, the noise would get quieter when the player touched the strings, even if there was no bridge ground wire!


According to this site, it is normal to touch the noisy pickups and the buzz goes away because the guitar is grounding me? So pickup buzz that goes away when touching metal parts on a guitar is NOt a ground problem but a SHEILDING problem. Not sure if this is 100% accurate for all senarios... Your thought?

[FunkyKikuchiyo]

fire - you're absolutely right. If something gets quiet when you touch it, then it is properly grounded. Terry was hoping you'd isolate some component that wasnt' grounded (I think) by probing around.

In the words of that article, right now your hardware and strings are "being a radiator or reflector" because they aren't grounded... same with your body. If you want to try it, you can do a simple experiment with alligator clips.

Or, shielding. Like I said, if you have really long lengths of wire in that thing that are unshielded, that'll do it in a heartbeat. Strats will be incredibly loud when absolutely no shielding is present, and that wiring doesn't run the same long lengths as your typical hollow body electric.

[big_teee]

That all sounds reasonable.Like Funky said, its worse on a single coil rig.
If its AC Hum the Humbucker should cancel it out.
A stratocaster with a RWRP middle pickup working properly is the best example of that.
My strat is in the worse case scenario. I play Sitting at my metal desk. It has a computer, printer, Phone, and a charging strip.
I have a ceiling fan turning right over my head with 4 Flourescent bulbs in it. I also am sitting a few feet from the amp.
It raises hell on the single coil, I can switch to pos. 2 or 4, and all noise goes away.
My humbucker guitars pickup a little bit here, but not bad.
I would still look for that bad or missing ground. I would alligator clip the bridge or a string to ground until you get it isolated!
Good Luck,

[fire]

Terry, I did the continuity test. I get continuity on the sleeve of the cord and the pickup covers. Not the from the Tip of the cord.... and both pickups read 00.5 ohms on the meter in all 3 switch positions...

[fire]

Terry, If I alligator clip the bridge or a string to ground does it matter where? Can I just ground to a vol pot? Also, what did you make out of my continuity test?

[big_teee]

I sent you a PM. It Will be easier to trouble shoot with PM or Email.

[Sweetfinger]

It is too bad someone butchered the guitar by adding an access panel but it does make a rewire go easier. The buzz that goes away when you touch one of the grounded pieces of the harness is normal. You need to install a string ground and shield all the internal runs and call it good.
There is one more thing that'll make you think a problem is worse than it really is- If your workbench has a bunch of outlets, soldering iron, and lights, it can be a much more buzzy environment than just playing in another room. My bench is quite the gauntlet for testing hum resistance. If I can get a guitar fairly quiet on the bench, it will be dead silent in actual use.