Guys im losing my mind with this grounding issue

[nickflook]

Ive read so many posts on here about grounding and everything, and its definitely made me build a better guitar with all your advice. Ive got an Ex-1 kit, the two humbuckers, 1 tone, 1 volume, and 3 way switch.

Ive installed a seymour duncan pickup in the bridge and an Ibanez INF2 in the neck, I know this is all wired correctly as Ive got over the diagrams a million time and rewired this thing twice. The pickups work and everything, i did the screwdriver tapping the pickups test and its all good. But the humming is out of control. Ive even tried running a wire from the metal part of the bridge pickup down to tone pot, as suggested in another thread, but this buzzing is still there. Ive checked the jack and everything, its all good. The thing is, all I have to do is touch any of the knobs or even just touching the jack with my hands and aaalll the buzzing stops and everything is a dream. So, knowing that, is there something im just missing, or are there any tricks to here? literally just touching the knobs or jack makes it all better, what can I solder to just make it think im touching those things all the time or something. This is clearly my first time doing this . Ive changed pickups before on other guitars no problem. . IM so close to having this all perfect, I just can NOT figure out this grounding issue. If somebody can help me and save my sanity I will literally buy and order a pizza to your house

[DrNomis_44]

That pretty much happens with any electric guitar, you could try using some copper foil or conductive paint to shield the tone/volume control routing in the guitar's body.

[nickflook]

im gonna try that, but I just know im doing something wrong here. I know guitars having noise and buzzing and stuff naturally, but this is just too much for it to be normal. I have the exact same pickup in another guitar and its pretty quiet compared to this one. I just spent so long putting this thing together I just want it to be perfect. Im gonna look into this copper foil stuff. THanks dude!

[gavinturner]

Hey Nick, did you run a ground wire from your bridge post to the back of one of the pots?

cheers,
Gav.

[DrNomis_44]

Definitely make sure you have the pot grounds connected all together, when I wire the pot grounds in a guitar I use a suitable length of tinned copper wire to link the metal shields of all the pots together, next I use some more tinned copper wire to connect any solder lugs of the pots that go to ground to the tinned copper wire on the pot shields, I tend to solder the bridge ground wire to the volume pot, shielding the routing for the control pots goes along way to getting rid of hum.

Also,

Check to make sure that none of the solder lugs on the pots have gone lose due to overheating from soldering, that can cause intermittent hum and noise problems.


As a side note, the passive control circuitry on most electric guitars tend to be high-impedance circuits which is why you get hum coming through the amplifier, high-impedance circuits are notorious for their ability to pick up hum and other electrical noise which is why it's a good idea to put copper foil/conductive paint in the control pot routing, the copper foil/conductive paint forms what's called a "Faraday Shield" when it's connected to circuit ground.

[dingobass]

Yep, sounds like a shielding issue.
Grab yourself a shielding kit from our store and shield all cavities, including the pup routs.
This will earth your pots and should stop the dreaded hum.

[nickflook]

Man I love you guys, the reason I got a pitbull kit is because everywhere I went everyone mentioned how this was the best forum. You guys seriously rock . Im gonna try this whole shielding kit thing and see what happens,.

I attached some pics so you can see what I got this thing lookin like so far, I wanted to make a guitar that looked like a nice piece of furniture lol . Ive been staining and sanding for weeks having a blast, and IM so close to getthing this electronics situation sorted out.

2547
2548

[stan]

good luck Nick, axe looks great

[kimball492]

Nick do make sure that you have a wire that is connected to the bridge itself normally one of the bridge posts run this to the back of a pot or if your putting foil in cavity run the wire to there . Good luck

[WeirdBits]

If you can, post a couple of pics of your control cavity just so we can have a look at your wiring. Extra sets of eyes can sometimes help to spot if anything out of place.

For general reference: Ibanez use red hot, blue ground, while SD has black hot, green ground.
http://www.seymourduncan.com/forum/attachment.php?attachmentid=47890&d=1383677229

[nickflook]

Hey guys, so I bought that copper tape from the site, it finally came! I got er all in there, plugged it in and instantly noticed no hum! I couldnt believe it, then I did the screw driver, tapping on the pickup trick to see if there was a connection, and now there isnt one.. which is why there was no hum.. I checked it before and the tap thing was working, is the copper foil not supposed to touch the pots or something? I think im missing a small step here, Ive attached pics, Did I over-do it and put way too much in? I didnt put any in the jack input part
28062807

[kells80aus]

This has probably been covered here, But, what I do is throw away the wiring kit that come with the guitar kit, and I build my own loom using shielded cotton covered wire and full sized pots(where possible). For solid body kits I layer all the routes with copper shielding. When I earth the bridge I tip some conductive paint into the bridge post hole to create a better contact. If I am building a kit with a fender style bridge then I find a place to solder the earth wire on.

Cheers PK

[nickflook]

Id love to not have to re-do all the wiring I had done, If I must, I will, and re-order new parts. But, Im just curious, before i put the shielding tape in, I had a connection and things worked, it was just very hummy due to not having any shielding. But once i put it in, nothing works. Im just trying to gain some more knowledge about all this stuff, is there something in there thats not supposed to touch the tape?

[dingobass]

First thing to check is have you got the bridge earthed (as PK suggested)
Secondly, my old favourite.... Have you got the output wired the right way round? :)

The pots should touch the copper, as this earths them without the need to run an earth wire from the back of each pot.
Saves on wire and looks so much neater.

Really like PK's idea of shielding paint in the bridge post holes, I usually strip a lot more off the earth wire and get it poking back up through the post hole.
This way, when I press the post in I know that there is a really good earth happening :)

[nickflook]

I think I just had an epiphany with with you guys are sayin, since my pots now have contact with the copper tape, it no longer needs the grounding wire i have going from pot to pot.. so if I rip that wire off you think it will make a difference? its starting to seem like that makes sense to me, but I have no clue what im talking about. And yeah, I double checked my output is wired right. everything was workin before this copper tape job. Im thinking its that grounding wire ive got going from pot to pot

[nickflook]

i just remember in the tutorial video, your ex1 wiring didnt work until you added that wire.. so I realize it must be an important one

[nickflook]

so i took that wire out, that wasnt it.. I think the problem is i have some bare wire touching the copper or something

[WeirdBits]

Just check that none of the lugs on the pots are accidentally shorting onto the copper shielding, as this would ground the output and cut the sound. Sometimes the pot holes or shape of the cavity will cause the lugs to touch the shielding. Either bend the lugs up slightly or put a piece of electrical tape under them to insulate them from the copper tape - but, you still want the pot body making contact with the copper. It could even just be a single stray wire strand hanging off a lug touching the copper, easy to miss and infuriating to try and find.

[nickflook]

i just tried everything and i think youre for sure right with the lugs hitting the copper. thats exactly whats happening and its the only thing I still have left to try to get this to work. if this works Ill paypal you some money so you can get yourself a pizza. all my hair has turned grey trying to figure this out

[nickflook]

WEIRDBITS !!! YOU ARE A GENIUS! that was it! everything was perfect except i had too much sodder on one of the lugs and it dripped down and was making a connection to the copper tape. oh man. I could cry im so happy right now, Ive been tyring to solve this forrreeverrr. I can finally glue this neck on! You gotta give me some paypal info so i can send you money for a pizza, seriously. LET ME FEED YOU PIZZA. Im forever grateful. Also, dingoboss and everyone else who suggested the copper tape, it TOTALLY got rid of that insane hum.

One last TINY thing i noticed. when i turn the volume knob, it crackles quite a bit, it works fine, just a little crackly, is that because i used too much sodder ? or do i need to blast some air into it to clean it out?

[dingobass]

Crackle could be a speck of dust but if its on the pot you over soldered it may be heat damage.
If you are using the stock pots this is real easy to do..

So, try giving it a blast or if you have it give it a squirt of contact cleaner as there could be some oxides formed from over heating..

If that dosent work replace the pot with new ones.. After swearing loudly for five minutes :)

[kells80aus]

If your in western side of Melb I have about a hundred large sized B500K pots if you need to replace a pot..
It's what can happens if you buy 20 from China they send you 150.

PK

[WeirdBits]

The crackle could be caused by the pot getting a little too hot when soldering or dust/crud getting in it. Just work the knob a bit and see if it clears or give it a blast of air in through the gaps in its casing. If that doesn't work you can get a can of electrical contact cleaner and give it a squirt of that... but, if it's cooked it may just be cheaper to replace it eventually.

Edit: too late, DB and PK already have you covered.

[nickflook]

I have no words for how awesome you guys are. I only just now really looked at the electronics upgrades, those better pots look insane compared to what i tossed in there. This has been one of the greatest learning experiences Ive ever had, Ive always wanted to know all about this stuff. Im almost glad Ive run into so many hurdles, because of you guys Ive fixed them all and now im far smarter because of it. My next guitar build will be epic, Im not even done this one yet and I cant wait for the next one. you guys are the best.

[dingobass]

We all started in the same way as you Nick, knowing very little :)

I have been refurbishing, ressurecting, repairing and building for 30+ years.
Through the generousity of the guys on this forum I reckon I have learned more in the past few years than in all the time before!

It has been a great pleasure watching peeps take those first tentative steps and gradually develop into competent Luthiers :)

[Nickosaurus]

Just a tip - using solder lug washers instead of soldering ground to back of pots avoids all of these issues :) can find them on ebay/electrical stores easily

[DrNomis_44]

WEIRDBITS !!! YOU ARE A GENIUS! that was it! everything was perfect except i had too much sodder on one of the lugs and it dripped down and was making a connection to the copper tape. oh man. I could cry im so happy right now, Ive been tyring to solve this forrreeverrr. I can finally glue this neck on! You gotta give me some paypal info so i can send you money for a pizza, seriously. LET ME FEED YOU PIZZA. Im forever grateful. Also, dingoboss and everyone else who suggested the copper tape, it TOTALLY got rid of that insane hum.

One last TINY thing i noticed. when i turn the volume knob, it crackles quite a bit, it works fine, just a little crackly, is that because i used too much sodder ? or do i need to blast some air into it to clean it out?


it might just be that the pot is a bit dirty and you just need to give it a spray with some Electrical Contact Cleaner, you can buy a can of it from most good Electronics Components stores (eg: Jaycar Electronics, Mouser), the stuff you want to buy is the stuff that doesn't leave an oily residue behind once it evaporates, if that doesn't fix the crackling you might need to replace the pot with a new one and be careful with the soldering, hope that helps.

[gavinturner]

Personally I always connect up the backs of my pot casings, but I also cut a plastic guard out of milk bottle for each and every pot to make sure the lugs can't contact the shielding. It's basically a wierd shaped washer that corresponds to the underside profile of the pot, with a hole for the shaft to stick through. I'm happy to take a little extra time connecting the pot casings if it means I dont have to troubleshoot shorts with the lugs!

cheers,
Gav.

[wokkaboy]

great tip Gav on the milk bottle plastic guard for the lugs to stay clear of the shielding, especially when the pots are recessed this can happen very easily. I'll try that tip next time !

[pablopepper]

Crackly pots can sometimes be fixed just by working them a little. Roll it back and forth to it's limits a few times. Zing!

[DrNomis_44]

A good thing to invest in if you're going to build more electric guitars is a good digital multimeter, you can pick up a reasonably priced one from most electronics parts stores, very handy when it comes to troubleshooting the wiring in electric guitars.

[dingobass]

Personally I always connect up the backs of my pot casings, but I also cut a plastic guard out of milk bottle for each and every pot to make sure the lugs can't contact the shielding. It's basically a wierd shaped washer that corresponds to the underside profile of the pot, with a hole for the shaft to stick through. I'm happy to take a little extra time connecting the pot casings if it means I dont have to troubleshoot shorts with the lugs!

cheers,
Gav.

Hey Gav, no need to join the casings if you have shielded.
Have heard a few old timer Luthiers say you can actually cause problems by over earthing!? (Your thoughts on this, Weirdy?)
I do like the plastic washer idea, especially on recessed pots like Woks pointed out.
My thoughts are the less heat you put into a pot the better :)

[stan]

don't know about too much earthing.
In this case "earth" is more of a common return path.
You can get ground loop issues, I guess... but isn't that more of an AC thing? as such more amp related... Our guitars are generally passive.
And copper linings,etc., are for RF shielding, which itself needs to be grounded, but does form part of the grounding...
My head hurts

[dingobass]

The same questions are running around my head too, Stan..

[Rabbitz]

It seems to me that some people are confusing "earth loop" or "ground loop" with the concept of "multiple earth paths".

Having multiple paths to ground is not, on its own, a bad thing.

The issue of "ground loops" arises when there are paths between grounds of different potentials. That is to say when different grounds are sitting at different voltage levels in respect to each other. This can occur when elements of a PA might be powered off different circuits or phases. Typically should these grounds be joined (looped) then it can introduce noise - usually seen as a 50 Hz hum.

In the case of a guitar, it SHOULD only have one ground reference - coming from the shield of the guitar lead. Therefore each of the earth paths within the body of the guitar should all be at the same potential - that of the guitar lead ground. For the purists, yes, the voltage drop over the wiring and high resistance joints etc can introduce a potential difference but as the wires are so short the drop can be safely ignored and if you have a HR joint there are other problems to solve first.

So if all the ground points, wires, shields etc are at the same potential, i.e. all go back to the single ground reference, then no voltage can flow between them so the multiple paths will not generate ground loop noise.

I hope that makes sense.

[keloooe]

Fair point Rabbitz, but guitars (normally) should have two though, one at the jack and another at the bridge?
Loops shouldn't really be common in guitars as the wiring always ends up at the jack, correct?

[Rabbitz]

Fair point Rabbitz, but guitars (normally) should have two though, one at the jack and another at the bridge?
Loops shouldn't really be common in guitars as the wiring always ends up at the jack, correct?


I am talking about electrical grounds - the bridge is just another earthing point. It does not provide a return path to a different earth potential.

The only path to electrical ground *should* be via the output jack ground.

If you have a path to a different electrical ground via the bridge and by extension the strings I don't want to be standing in that spot holding that guitar - who knows what stray voltage you might experience...

I would expect that it is important to make sure the bridge is grounded (I haven't really thought about this) is that the string are probably a pretty good antenna, and may have voltage (and therefore noise) induced into them - grounding them will overcome this.

I am more than happy to be corrected on any of this. I have experience in electronics/radio/electrical but not a lot of experience of guitar electrics per se. (I've plugged plenty of 'em in, and repaired a few that had electricals come to grief, but I've never looked at the electrics in detail...