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Grounding Issues

Discussion in 'Tele-Technical' started by nelsonizer, Aug 12, 2017.

  1. nelsonizer

    nelsonizer TDPRI Member

    Age:
    28
    3
    Aug 12, 2017
    Ohio
    Hi Everyone,

    This is my first post and I need to some expert help on my guitar wiring. I've never opened up the back of a guitar so I am starting from 0. There are no guitar shops where I live so taking it to somebody who knows what they are doing is not an option.

    My guitar is a Fender FSR Custom Telecaster HH Goldtop (two humbuckers with a push pull coil tap) and it hums really badly, especially when the fridge or air conditioner turns on. If I touch my hand to the strings, the hum stops. Today, I plugged it into my Focusrite interface plugged into my macbook and I when the back of my arm touched the strings it gave me an electric shock.

    The hum started the other week when I noticed the output jack was loose. I unscrewed the jack and tightened it with some wrenches I had laying around. Now it give me little shocks and the hum is permanent instead of every once in a while. I did some googling and it looks like there is a ground issue or maybe I messed up the output jack.

    I'm living abroad for the moment. The house I am staying in is 220V and there's no guarantee the wiring is done according to any standard. Might be a factor. Here's some pictures of the guitar wiring:

    [​IMG]

    [​IMG]
    Help!
     

  2. Ronkirn

    Ronkirn Doctor of Teleocity Vendor Member

    Age:
    71
    May 1, 2003
    Jacksonville, FL
    first thing... plug her in like you were gonna play it.. take a scrap piece of wire and touch the bridge/strings and the control plate/ground point and see if the hum vanishes.. if so just connect a ground wire from a contact point on the bridge to a ground point in the electronics cavity..

    rk
     

  3. Lake Placid Blue

    Lake Placid Blue Friend of Leo's

    Sep 24, 2016
    California
    First of all, I would listen to Ronkirn. He's the pro as far as I'm concerned. I've read his suggestions and discussed them with techs who either say they do the same or say "I never thought of that. That's a great idea!"
    Second, welcome to TDPRI. Glad you're here. You'll find lots of good people and advice. Now, could you post some pics of the rest of your guitar so we can all be green with envy
     

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  5. Ronkirn

    Ronkirn Doctor of Teleocity Vendor Member

    Age:
    71
    May 1, 2003
    Jacksonville, FL
    under closer examination of the photos.. it would appear as though it's been "tinkered" with before... the solder connections on the Pot, both the black lead that goes from the pot case to the switch frame look amateurish, also the green lead, soldered at or about the same point on the pot case looks like a DIY job.. so you may have other issues underlying..

    if the simple version I posted earlier dosen't do it.... try this... unsolder the pickup connections to the electronics and connect them directly to a guitar cord, and plug it in... see if the buzz persists... then try the second pup.. if the buzz is in one and not the other pup, it's possible there is a wiring fault within the pickup.

    There is no harm that can come from wiring it directly... nothing's gonna blow up.. it just removes the guitar's electronics so you know what is causing the problem.

    rk
     
    summer_69 likes this.

  6. summer_69

    summer_69 TDPRI Member

    76
    Sep 22, 2008
    Denmark
    Occasionally you do meet people who know well what the are doing even if they do not work in guitar shops. Also, from what I have heard (on the internet - that should guarantee the validity of facts), not all who work in guitar shops knows what they are doing.

    Are coil tap, push/pull pot and cable tie original? Is it with any combination of pickup/coil tap? Does the hum appear also if you plug into an instrument amplifier? Some audio interfaces can hum some if not using the right power supply suitable for the local line voltage and frequency. Could the instrument cable by the guilty part? Do you have tools and soldering iron and (preferably) a multimeter besides the some wrenches?

    Welcome to the forum.
     
    Last edited: Aug 12, 2017
    viccortes285 likes this.

  7. Controller

    Controller Friend of Leo's

    Jun 11, 2010
    Montana
    If I can solder, believe me, anyone can solder. Lots of You Tube videos to get you going. It may not look pretty but you should be able to get where you are going with Ron Kirn's advice and lots of helpful hints in TDPRI. Let us know how you come out.
     

  8. R. Stratenstein

    R. Stratenstein Doctor of Teleocity

    Aug 3, 2010
    Loganville, Ga.
    I am more concerned about you being shocked.

    You should not be shocked, ever, in a properly-functioning guitar-amp setup. If there is another AC-powered piece of gear involved, this might explain the shocks, but your comment about no assurance the house is properly wired is a little bit scary, along with the fact that you are being shocked with a 220 V system.

    This has probably been an underlying problem, and your guitar has developed a fault whereby you are becoming the ground path for some of the amp's current.

    The amp and wiring need checking, IMO, and it very well may correct the hum, as well. First check--If the system you're on uses a grounding (third wire system here in the US) lead, have it checked for proper function.

    Can you unplug the amp's power cord, rotate it so the prongs are in the opposite receptacle holes? See if that makes a difference in the hum and/or the shocks. Second, can you take your amp and guitar to another building where you know the wiring is correct?

    EDIT: Just re-read your post. Is the Focusrite USB powered or 220V? If 220V, insert "interface" in place of "amplifier" in my comments above.
     
    Last edited: Aug 12, 2017
    SURF likes this.

  9. Ronkirn

    Ronkirn Doctor of Teleocity Vendor Member

    Age:
    71
    May 1, 2003
    Jacksonville, FL
    220 volts? In Ohio?? what kinda amp is he runnin'.. some mega kilowatt behemoth? should be 110 VAC..

    rk
     

  10. nelsonizer

    nelsonizer TDPRI Member

    Age:
    28
    3
    Aug 12, 2017
    Ohio
    Thanks everyone for being welcoming and responding to my troubles. Here's a picture of our problem child:

    [​IMG]

    I had some wire wrapped around the strings touching the bridge then touched the other end to the outside of the control plate while the cable was plugged in. That didn't seem to make a difference.

    Next, I unscrewed the jack with the like the second picture in the OP, and touched the end of the wire to each of those poles. One of the poles cut the guitar sound completely and the other pole didn't seem to have any effect.

    Checked with a different cable, hum still there. Don't have an amp on hand but I remember I plugged into my brother's Line 6 amp at his house in Ohio (built in the 1920s, doesn't have third prong) and it was shocking me when I stepped on the metal air vent.

    Google says the guitar came with a coil tap but whether or not the electronics have been modded, I can't say. Bought it at a non-music shop, guy didn't know the history.

    Born and raised in Ohio but currently living in Africa. My compound runs off a semi-trailer sized diesel generator in 220.

    ----------
    Update: I've been fiddling around with the guitar according to suggestions posted above and managed to eliminate the hum in some cases.

    No Hum; No Shock: Guitar plugged into Focusrite (Focusrite runs on only USB power), Focusrite plugged into Macbook, no macbook charger attached

    Occasional Low to Moderate Intensity Hum; No Shock: Guitar plugged into Focusrite (Focusrite runs on only USB power), Focusrite plugged into Macbook, three prong charging cord attached to Macbook into 220V wall outlet

    Persistent Severe Hum & Shock: Guitar plugged into Focusrite (Focusrite runs on only USB power), Focusrite plugged into Macbook, two prong charging cord attached to Macbook into 220V wall outlet
     

  11. dsutton24

    dsutton24 Poster Extraordinaire Ad Free Member

    Dec 29, 2010
    Illinois
    That's a peculiar set of circumstances. I'd have thought that what you are describing would be impossible.

    I just Googled 'getting shocked off USB port Mackbook' and apparently it's a pretty common complaint.

    Interesting.
     

  12. BryMelvin

    BryMelvin Tele-Afflicted

    Age:
    65
    Jan 4, 2014
    Arivaca AZ
    It sounds like your compound generator has no ground to earth. Get someone to put a ground cable from the generator chassis to a ground point (copper rod or a pipe) in the ground.
     
    moosie likes this.

  13. Ronkirn

    Ronkirn Doctor of Teleocity Vendor Member

    Age:
    71
    May 1, 2003
    Jacksonville, FL
    generator?? might be your problem... generators, specially one stuck in some remote location can be umm.. less that well "filtered".... your guitar may be fine...

    Reminds me of the mid 70's... I'm head of photography for one of NBC's premiere stations... we're migrating from 16mm film to "mini-cams.." video tape...

    The station orders a Bosch-Fernseh .. the top of the line.. in 1974, it was 200,000.00... works out to about a million today...

    So we get a "gig" to film, I mean tape a couple of commercials for a land developer... it's in Back-(blanking) no where. The nearest electricity is in the brand new Digital watch I just got from The Sharper Image, so.... we have someone go rent a generator... a big nice one....

    hour later.. they show up.. fire that puppy up .. the engineers check it.. it's at 117 VAC, and they give us the thumb's up...

    I plug in the power supply... and it works for probably 10 seconds before the "back pack" starts oozing blue smoke.... the engineers mumbles something about some plucking' sunny beach, I had no idea what they were talking about...:rolleyes: but.. needless to say.. the "shoot" was over for the next month or so..

    not all generators are created equal...

    this is that 30 pound monstrosity... what ya cannot see is the 45 pound back pack that accompanied it, and the 12 pound battery belt ya had to wear...

    rk

    kcncamera750-2.jpg
     
    LutherBurger likes this.

  14. R. Stratenstein

    R. Stratenstein Doctor of Teleocity

    Aug 3, 2010
    Loganville, Ga.
    With the three-prong plug, helping at least some, it sounds like the generator is grounded, but like Ron, I have had my share of problems with generators. Is there enough oomph in your MacBooks battery to last through a playing/practicing session for you, so you don't have to fool with it? Possibly the charger for your MacBook is faulty, but the thing that dsutton found may be at the heart of the problem.
     

  15. summer_69

    summer_69 TDPRI Member

    76
    Sep 22, 2008
    Denmark
    One thing that might help with electric shock things - and maybe the hum - is a wireless instrument connection between the guitar and whatever you plug it into. If you use battery powered effect pedals you can have them on the You-and-guitar side of the wireless.

    Another and better way would be to power the laptop from a high capacity (car or truck) accumulator with a suitable adaptor and then use the generatior only to charge the accumulator. Otherwise you might also end up destroying the laptop. Thats what I would do in your situation.
     

  16. nelsonizer

    nelsonizer TDPRI Member

    Age:
    28
    3
    Aug 12, 2017
    Ohio
    Sounds like it's a generator/electrical supply issue. Though I'm still concerned I will hurt myself if I plug the guitar into an amp.

    Are there any safety checks I can do to make sure the guitar itself is properly grounded?
     

  17. Barncaster

    Barncaster Poster Extraordinaire

    Feb 3, 2010
    Spain

  18. tessting1two

    tessting1two Tele-Meister

    222
    Apr 13, 2014
    Southern California
    Does this mean that there was a recent point in time before the output jack came loose where your entire rig, including the generator, was functioning properly and you weren't getting shocked or excessive hum?

    If so, and I was going to approach this logically, then I would start with: "it worked before the jack came loose" + "it didn't work after I tightened up the jack" = "something is wrong with the jack or the wires connected to it"

    The generator and step down converter grounds are definitely suspect, but working from "small to big" the soldering job on that output jack isn't exactly tidy and there appear to be stray fibers or strands of wire. I would clean all that up and shorten the white wire so it doesn't get pinched or twisted when you put it back in the guitar. And if there was any chance something was wrong or deteriorated in that jack I would replace it with a Switchcraft just to be safe.
     

  19. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    Hum is a persistent and sometimes inherent/unsolvable problem when running off a generator. Cleaning up wiring is not not going to solve anything unless parts are touching things they shouldn't.

    A step-down converter is only part of the battle. In most cases an isolation transformer that is also a voltage regulator is required - and in most cases absolutely required if running any digital equipment like computer gear, digital effects, modeling gear etc.. Even then, because of the lack of an earth ground all stray RF frequencies floating around will be picked up by the guitar. Adding shielding to the guitar itself may help to a a degree (you can find plenty of articles on the internet about this - use Google), but it's likely you will not be able to completely eliminate hum.
     

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