New hum for some reason

FAC

FAC

New member
Folks,

I have a stock G&L ASAT with the newer magnetic field design pickups...never changed anything but the strings on this guitar. I picked it up used in mint condition and it has always been hum free in the middle position (neck and bring pickups together). It is one of my main guitars and I play it very frequently.

Tonight, it started humming in the middle position (not as much as neck or bridge alone with their typical single coil hum, but way way more than usual). Nothing has really changed in my setup. Other than the hum, the guitar sounds the same. I checked my Squier Strat in hum canceling positions and it was silent (which to me rules out some anomalous power issue, etc.). I removed all the pedals and ran straight in, as well...still there.

Any ideas what might be going on, or what I should check? I am totally comfortable installing pickups, etc., if there is something I can look for...ironically, I never touched this one, and as I recall, I have never even opened up the control cavity, so I am at a loss as to why it changed.

Thanks everyone.
 
Re: New hum for some reason

Take out your VOM and test for conductivity between the ground (from your cable) and the bridge/strings. Then with vol knob at 10, measure resistance of neck, bridge pups and in parallel (middle) position. Then see if the nominal values for your pups are close (not exactly the same - remember you are still measuring pups inside their wiring) to the measurements. Last do the maths and check that the nominal value for the parallel position is close to what your VOM reads.
 
Re: New hum for some reason

The first thing I'd do is try going around the pickups, pots, jack, & any other metal pieces to see if touching them grounds them out, if so you're problem lies within or around that component. If not, pull the harness & check all your grounds & solder connections. If you still haven't found the issue check the rest of the wiring for other obvious salutations or reasons for the noise.

I'm guessing its probably the switch or the jack as A.S.A.T.'s are known for failing switches jacks but it's hard to say without additional information. These are both easily fixed and cheaply obtained parts so whatever the problem is I wouldn't worry about it to much. Do you notice any difference in the pickups when you use them by themselves or do they sound the same except in position 2??? If you still can't find the source posting pictures can be quite helpful ....
 
Re: New hum for some reason

Thanks for the input. I opened it up and a lot of the solder joints were not so great, and the bridge pickup lead was actually loose where it met the switch. The ground leads from the pickups were also barely tacked to the back of the volume pot. I reflowed most of the solder joints and checked everything for continuity with the meter and it was fine...but there was essentially no change, other than peace of mind that I knew for sure the wiring harness was soldered correctly.

I then examined the neck pickup because it is easy to access...there was an extra spring in there, and I hoped that it had made some wonky contact and that would do it...removed it, but nope.

To try to isolate the switch, I then soldered the two pickup leads directly to the jack...no change. This suggests to me that it resides with the pickups or the jack. Unfortunately, the jack is problematic to remove and examine.

One funny thing...the ASAT schematics show a ground wire coming from the bridge...but there isn't one...just the ground wire from the bridge pickup**...but the bridge meters in continuity, so it is grounded. I think maybe someone tied the bridge grounding wire to the bridge pickup wire maybe? Or, could this be it even though it meters as grounded? My next step would be to remove the bridge, I guess, but I was not up for doing that today (it is a bit more involved than what I've done so far).

Sorry for the long post, but I wanted to give an update and thank everyone for their suggestions.

Edit: **since I did not remove the bridge, all I really know is that there is one ground wire coming from the bridge area and I made the assumption that it was the pickup ground wire...I don't actually know this. I suppose it is possible that the wire is the bridge grounding wire and perhaps the bridge pickup is somehow wired to the bridge? I'll know for sure when I yank the
 
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Re: New hum for some reason

Does it still get better when you touch the strings?

Do the pickup wires have a shield?
 
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