Ground Hum Problem

[billy_mill]

Hi fellas,

My tele has developed a bad ground hum which goes away when you touch the controls knobs or neck pickup (but not the bridge itself). I took the control plate out but everything looked in order, good solder, no dodgy wiring etc.

As I had a couple of new CTS 250k pots lying around and that the hum may be coming from a bad solder joint, I replaced the pots and redid all the wiring. Plugged it in before but the hum is still exactly the same.

Anyone got any ideas where the hum can be coming from? Nothing new has changed in the house in the way of lights etc that may cause ground hum. Anywhere elso on the guitar I should be looking?

By the way, what's the best value cap for a tele?

[fezz parka]

Is the neck cover grounded like it should be? That what it sounds like to me.

As far as the tone cap goes, it's pretty much up to you. I use .1's, .047's sound good to my ears as well. This below is by far the best thing you can do to a tele:



Similar to the 50's mod for LP's this allows you to roll back the volume without the usual treble loss.

[billy_mill]

Thanks Fezz, I didn't know about any grounding on the neck cover. How do I check this?

I've done the 50's mod on my les pauls and really like the way the tone cleans up when you roll the volume back. Does the wiring diagram you show have the same effect? Have you got any links showing the wiring in more detail? Mine is wired similar except the wire from the outer lug of the tone pot goes to the outer lug of the vol pot (the one opposite the lug the cap is on).

Cheers

[fezz parka]

Just move the wire from the outer lug of the volume pot to the center lug. That's all it takes. Here's a larger wiring diagram with the original wiring (No mod). If your neck pickup isn't a three wire like the one shown below, you'll have to pull the pickguard and check the pickup itself.

[billy_mill]

Nice diagram Fezz, that's exactly what my wiring is like. I have just resoldered the wire to the centre lug and I'll have a play later.

So what about the grounding on the neck cover, where do I check for this?

Cheers

[photoweborama]

I'll have to pull my plate tonight and change this.

By the way, my tele developed a bad hum and it appeared if you press the pickguard it would go away. My Tele is shielded and I thought the pickguard was not being grounded, so I added a copper strip from the control plate to the pickguard. But it did not fix it.

It ended up being a loose jack. I cranked it really tight and it all stopped.
Same symptoms. It played perfect and then just one day started buzzing.

[photoweborama]

Ok, I've done the mod. By the way the bigger drawing does not show the mod, you have to go off of Fezz's smaller picture is what you want to go by for the mod.

It does indeed work.

I also changed to a .01 cap. I tried a .047, and I had a .022 in it, but the .010 seems to add more twang to the bridge pickup and also seems to tame some of the boomieness of the neck pickups.

I always use .022, but in this case, the .010 seems to work better.

[fezz parka]

Way to go Mark! This way is much better than the cap/resistor bleed stuff. And it's so simple.

[billy_mill]

I did the mod Fezz suggested and it worked a treat. Volume control works just as I like it now. Cheers Fezz.

However the ground hum is still there and driving me bonkers. Anyone got any more suggestions to check.

Fezz, when you mention grounding on the neck cover, do you mean the metal plate with the four screws holding the neck on?

[fezz parka]

In the diagram above it shows three wires coming from the neck pickup. The yellow wire is the ground for the p/u cover. Check to make sure the yellow wire is grounded, on both the pot side and the cover side.

[billy_mill]

I see what you mean now. However, my tele has only got two wires from the neck pup, a black and a white. They are wired as in your diagram above, with the white wire going to the selector switch and the black wire grounded to the volume pot.

Does this mean the neck pup is not grounded?

Thinking about it, I think the hum began not long after I adjusted the height of the neck pup. Could this have something to do with it?

[fezz parka]

The cover ground is on the pickup then. Check the neck pickup. Does yours screw into the body, or is it pickguard mounted? If it's guard mounted, just remove the guard and check it out. If it's screwed into the body, you'll have to remove the pickup. Do you have a DVM?

[billy_mill]

Fezz, the neck pup is mounted on the pickguard. I had removed the pickguard earlier just before you posted back. The neck pup is sitting in it's recess.

I have got a digital voltmeter (DVM?), sitting next to me in fact.

[billy_mill]

I've just checked continuity between the neck pup cover and the volume pot and it's good. The neckpup cover is definitely grounded.

Anything else to check for?

[fezz parka]

Does it hum on the bridge pickup setting? Can you stop the hum by touching any metal part aside from the bridge/strings?

[billy_mill]

I think it hums on the bridge pickup setting. The best thing to stop the hum is to touch the vol or tone knob Goes totally silent then. Touching the bridge does not stop it.

[fezz parka]

Does it stop when you touch the jackcup? Somehow the bridgeplate has lost it's ground. Check for continuity between the bridge and control plate. If there's no continuity, the bridgeplate isn't grounded.

[billy_mill]

I'll need to check the jackcup tomorrow to see if the hum stops when it's touched.

I've just checked, and there's no continuity between the bridge and the control plate/pot ground etc., so it does sound like the bridge is not grounded.

In what way is the bridge usually grounded?

Thanks for all the help by the way.

[fezz parka]

There could be a wire that goes from ground on the pickup to one of the mounting screws, or sometimes there's a ground wire with the end stripped back that just lays between the bridgeplate and the guitar body.

[billy_mill]

I'll take the bridge off tomorrow and make sure it's grounded. That's got to solve the problem.

I've never taken the bridge on a tele. The two screws at the rear obviously have to come out, but what about the three around the neck pup?

[fezz parka]

Which Tele do you have? There should be three or four screws beneath the saddles that hold the bridgplate down. Take these out, and the bridgplate will come right off.

[billy_mill]

It's an ash fender mim. It's OK, I couldn't see the other two screws beneath the saddles. I removed the bridge and the ground wire from the bridge pickup to the bridge ends with a circular do-dah that goes around the screw of the pickup. This had somehow worked its way over the rubber spacer, hence no ground to the bridge. I fixed it back in position and ensured there was a good connection. I'll plug it in tomorrow to see if the hum's gone.

Cheers.

[fezz parka]

That should do the trick!:yay

[photoweborama]

What I did on mine was solder a wire from the volume pot and fed it through the hole to the bridge pup cavity.

Then I soldered the wire to a piece of sheet copper about an inch wide and about 3 inches long and ran it under the bridge plate. This gave a wide surface for ground contact. I don't like it when they put just a bare wire under the bridge because I've had it make the bridge not sit flat on the body at times.

[fezz parka]

That's a great idea Mark!

[photoweborama]

That's a great idea Mark!

:ty
:)

[billy_mill]

Well, I plugged the Tele in earlier and the ground hum has gone. Unfortunately there is now a problem with the bridge pickup. The sound is really tinny (almost like the treble most setting of a wah). Any ideas what's happened?

[fezz parka]

Make sure that the ground wire you fixed isn't making contact with the pickup windings or the wires coming off the pickup. That little circular doohckey can sometime turn and make contact...

[photoweborama]

Man! Poor Billy's have a rough time!

[billy_mill]

You don't know the half of it. My temples have swelled up for some reason. I look like the friggin' elephant man.

Knowing my luck, I'll probably fix the bridge pickup and find I've lost my left knacker. :)

[refin]

You don't know the half of it. My temples have swelled up for some reason. I look like the friggin' elephant man.

Knowing my luck, I'll probably fix the bridge pickup and find I've lost my left knacker. :)

Let's hope for a loose ground only......

[Dr Fene]

Hey Billy good luck with the Tele and if youy are around 16-18 years old watch out for MUMPS My 17 year old has it and so does half the college!!