Tracking Down Hum

[tblackburn54]

I have a newly acquired used G&L ASAT Blues Boy. Works great except for one thing. It has a hum when I select the bridge pickup. It goes away if I touch the strings. There is a Set Lover humbucker in the bridge position and I think a Lill 59 Humbucker in the bridge position, but I can't get a hit on the part/model number on the back.


Here is a link to the G&L website that shows very simple wiring diagram. (http://www.glguitars.com/schematics/LWF0001Bluesboy.pdf that show the very simple schematic. With the two Seymour Duncan pickups there are 500 k pots for volume and tone with a push pull switch set up for the tone. It is a three position blade switch.

My first step in troubleshooting was to see if the problem was in both pickups. It is only in the bridge.
My neck step was to verify the wiring diagram.When I try to make heads or tales of the wiring and get lost in the headlights.

There is a wire that lays under the ashtray for the bridge pickup and from what I read that is normal. It is not soldered to the pickup hardware.

I hope someone in the forum can enlightened me. I have taken several pictures that I hope will further illustrate my setup. Any help would be greatly appreciated.

 

[guitarSQUIRELL]

Re: Tracking Down Hum

To me it sounds like a grounding issue. Have you checked all the grounds? I notice it's also a push pull. Do you get a hum only when you have it pulled or is it humming all the time?

 

[beaubrummels]

Re: Tracking Down Hum

Sounds like the bridge plate of the guitar is not grounded. (The bridge itself, not the pickup.)

(or perhaps the bridge pickup is always split. humming like a single coil. that last one is a guess.)

 

[uOpt]

Re: Tracking Down Hum

I can't quite parse the OP.

 

[tblackburn54]

Re: Tracking Down Hum

What is "OP"?

 

[tblackburn54]

Re: Tracking Down Hum

The hum only occurs when the push/pull pot is pushed in other wise quiet. Ran a jumper to other grounds from bridge plate with no change.

 

[tblackburn54]

Re: Tracking Down Hum

I have been eliminating hum from my system for a while and this is all that is left. Only have two electrics, this one and a fender strat. The bridge pickup on the ASAT with the push/pull pot pushed-in is the last piece of hum I have found. I used to assume the hum was form lots of things ( tube amps, single coils, bad cables, etc...) .and overlooked it a lot. Between bands and first time in a while I have been able to spend some time on it. Have played in a pretty noisy environment and it was not a an issue before. I really don't know how this thing is supposed to be wired. I am a also not sure what pickup is in the bridge as I cannot correlate the numbers on the back with any database. I appreciate all of your comments.

I think it is a wiring issue, but cannot find a wiring diagram to follow with my configuration.

 

[uOpt]

Re: Tracking Down Hum

You say the seth is in the bridge and the little 59 is in the bridge.

 

[tblackburn54]

Re: Tracking Down Hum

You say the seth is in the bridge and the little 59 is in the bridge.

Seth love in the neck position and what "looks like" a Little 59 in the bridge. Do not have much history with Seymour Duncan and hence why I am unsure.

 

[tblackburn54]

Re: Tracking Down Hum

I have been eliminating hum from my system for a while and this is all that is left. Only have two electrics, this one and a fender strat. The bridge pickup on the ASAT with the push/pot pushed-in is the last piece of hum I have found. I used to assume the hum was form lots of things ( tube amps, single coils, bad cables, etc...) .and overlooked it a lot. Between bands and first time in a while I have been able to spend some time on it. Have played in a pretty noisy environment and it was not a an issue before. I really don't know how this thing is supposed to be wired. I am a also not sure what pickup is in the bridge as I cannot correlate the numbers on the back with any database. I appreciate all of your comments.

 

[beaubrummels]

Re: Tracking Down Hum

What is "OP"?

Original Post

The hum only occurs when the push/pull pot is pushed in other wise quiet. Ran a jumper to other grounds from bridge plate with no change.

Yeah, that's likely when it's split to single coil - hence no humbucking, hence the hum (though I would have expected up to be split/single). Welcome to the world of single coils. They pick up hum in addition to string vibration. Which is why humbuckers were invented.

Your description sounds normal to me, but like yourself I would work on ways to get around it, like keep amps, computers and electronics away from the guitar while playing. Maybe try shielding the pickguard and cavities, if not already shielded. Check your power source/outlet and make sure there are no lights and especially no lighting dimmers plugged into the same circuit. If there is a lighting dimmer on the circuit and you can't separate your amp/guitar to a different power circuit, make sure the lighting dimmer is either on full or completely off while you play.

 

[tblackburn54]

Re: Tracking Down Hum

Ok, then I will assume this is related to the power source and will try to find a clean circuit to test this is on. Although my Fender strat has single coil P/U's and does no have this problem. I also would have expected the coil splits when pulling the pot up on the push pull switch. I may consider changing this.

 

[Cme]

Re: Tracking Down Hum

When selecting only the bridge pickup, which way sounds brighter and has less output? With pot in/down or out/up? That should be single coil. If it's not up/out, I think it might be wired wrong. And that could be why it hums. If your other single coil guitar is quiet, this one should be similar imo.

 

[tranceking]

Re: Tracking Down Hum

www.prosoundweb.com/article/eliminating_troublesom_hum_buzz_created_by_electric_guitars/

Sent from my NX403A using Tapatalk

 

[tblackburn54]

Re: Tracking Down Hum

I have the strings off right now so doing this without strings. There two rows of magnets. When the pot is pushed in both rows of magnets sounds the same (I am using a nail clipper and tapping on the magnets).
When pulled out, the row closest to the rear of the guitar sounds brighter than the other row.

There is my story and I am sticking to it!

 

[tblackburn54]

Re: Tracking Down Hum

Good article. I read it and than for bringing it to my attention.

 

[tblackburn54]

Re: Tracking Down Hum

I found my problem. The bare wire coming from the bridge pickup and connected to the push/pull switch was broken . Visually it looked connected until I used a magnifying glass. I was trying to identify what wiring schematic was the most accurate. I looked at the recommended diagrams on the Seymour Duncan website and could not find a good match, I also looked at the www.guitarelectronics.com as recommended by Seymour Duncan. End the in I almost got ready to rewire the guitar but luckily found the loose ground wire.

Thank you all for your help!

 

[guitarSQUIRELL]

Re: Tracking Down Hum

Awesome glad you found your issue. Sometimes a magnified eye helps on prijects like that.

 

[Shooter.556]

Re: Tracking Down Hum

Check your grounding.. Most 60 cycle hum comes from a floating ground.. Check your jack and the ground wire on the bridge..