Terrible hum when TV is on in room

[eyemack]

OK, so the shielding went OK for a first time. Bit rough around the edges, but I can live with that. I checked continuity throughout, and all seemed OK.
However, there is good and bad news.
The good news is that the hum without touching the strings has significantly reduced.
The bad news is that I now get a lot of hum if my hands are near the pickups, whichever one is selected.
Also, I feel I haven't put the pickups back particularly well, as the covers don't move very easily and I can't get anwhere near the required height. can't get low enough gap.
I feel I'm getting in a mess here and might have to seek the help of a local luthier!

[alexpigment]

When you say you didn't put the pickups back well, do you mean that you may have inadvertently "drilled" (via the screws) new holes rather than going to the original holes? Or perhaps do you think you may have put the foam under the pickups in wrong? If the latter, I would make sure that each strip of foam goes under the bottom on either side of the pole pieces, not directly under them. Assuming that the foam is in the original location and you're not screwing down into the body at weird angles, I can't think of why you can't get the back to the same height.

As for the "hum when nearing the pickups", this is something I've seen reported quite a few times over the years, and I honestly can't say if there is a general consensus on the cause. I would save this until you get the pickup heights sorted out, as there may be a common factor between the two (e.g. something under the pickups is touching something it shouldn't).

EDIT: You may also want to test the battery powered amp just in case. You mentioned that the hum problem doesn't occur with that amp, and that seemed quite suspicious (and likely unrelated to the shielding-related issue). It's worth pointing out that these tests must be done when the guitar is oriented in the same direction, though, as EMI-related hum is directional (in all 3 dimensions).

[eyemack]

Thanks again.
I will look at all that in the morning. I need a break. And a beer or two!

[alexpigment]

Totally understandable. I did some googling and found these two results:

https://www.thegearpage.net/board/index ... g.1757575/

https://www.talkbass.com/threads/pole-p ... l.1229441/

Hopefully there's an a-ha moment somewhere in there. The 2nd thread is about noise when you *touch* the pickup pole pieces, and I'm not certain that's the same as what you're describing. However, it would be pretty easy to do on a JM pickup, since you can just use the same copper tape and make it touch the solder joint for the pickup's grounding wire. The 1st thread makes the problem seem more ubiquitous and inconsistent, as it points at a factor in the environment or in your own body. Can't say I've run into that before (and I'm specifically testing my guitars), but again, I've definitely seen it reported many times.

[eyemack]

So, a new day and things are looking better!

I think a little summary would be useful at this point.

1) the issue was very bad hum, only when the TV in my music room was on. Everything was OK when switched off with just the usual residual level of hum.
2) the hum was there with my Strat and Tele, but pretty insignificant compared to the JM.
3) after great advice here from you guys, I applied copper sheilding tape to the cavities, and although a bit rough round the edges, that went OK. See here https://imgur.com/a/7X3D6yI (don't laugh!)
4) after the shielding, the hum from the JM without touching the strings was hugely reduced, about the same level as my other guitars, so that was good. Remember, this is all only when the TV is on.
5) the down side is that I am getting hum when my hand is near any pickup, which is obviously an issue when playing.
6) I tried the JM with the battery amp, and the hum coming from my hand when near the pickups was there. Also, I tested on the Strat and Tele and it is also there but not as pronounced as the JM. My suspicion is that this hum was always there, but I didn't notice it because the original issue hum was so bad! Also, on the battery amp and the other amps I'm testing at a volume level that I wouldn't normally use in that room if the TV is on. So, that sort of backs up what I think.
7) re pickups after re-assembling JM. I lifted the pickguard this morning, and found that the pads below the pickups had moved and were not in the correct position, so I adjusted them. That improved the situation enormously, and the neck pickup can be adjusted ok. I still have a bit of an issue with the bridge pickup as I cannot raise it more than 8/64". Normally I would have it around 6/64". It just doesn't move as smoothly as it should. There is a (blue) wire that looks in an odd place that might be restricting the movement, but without soldering, its position cannot be changed. See here https://imgur.com/a/cNm13T5. What do you guys think?

As always, thanks a lot for your help with this.

[alexpigment]

Can you flip the pickup 180 degrees so that the wire just goes straight to the wiring cavity?

(That’s what the wiring diagram (link on page 3) shows as well)

[eyemack]

I’ve always found the wiring diagram confusing, particularly as it is ‘as seen from below’ the pickguard, but that’s just me. Also because it doesn’t show the body and the long run some of the wires have to take.
My gut feeling is that doing a 180 will not be possible because the black wire won’t be long enough. I could have another look. Also, that would mean 2 wires going down the side rather than 1. It won’t even go under the pickup as it’s wrapped round another pin. Soldering would be needed.

[alexpigment]

Gotcha. I presume the blue wire is run between the foam pieces rather than under them, correct? Also you mentioned that it’s hard to screw down and I’m still wondering if you may have accidentally created new holes that are at an angle (and would make it impossible to get low once the angle gets too great). If you back the pickups out, do any of the screw legs feel particularly angled into the body?

[eyemack]

Thanks again.
Don’t think I said I had problems trying to screw it down, it’s the opposite. As I said above, I can’t raise it enough to make a gap less than 8/64”. The holes are the original ones and are very easy to use.
The blue wire runs along the side of the pickup, not between the foam or underneath.

[alexpigment]

Ah, I misunderstood. I suppose the foam may have collapsed a little bit over time (or the foam pieces got rotated maybe? ). At any rate, you can basically cut up anything and put it under the pickup to raise it up. I tend to use a foam mouse pad and stack as necessary, but you could get away with cardboard. No need to be precise the height, as the foam can compress down.

[eyemack]

I've fixed it!
It was possible to get the blue wire to go under the pickup and not along the side. Moves nice and easily now with height adjustment no issue!
So, at the end of the day, the shielding was worth it despite the now-annoying hum from when my hands get close to the pickups. Still, it's a big improvement.
Thank you all for your help. It has been very much appreciated.

[alexpigment]

Awesome - glad to hear that! As for the hum when you get your hand close, does that noise only occur when the TV is on, or does it occur at all times? Also, if you touch the strings with your left hand, does it still occur when you move your right hand near the pickups? Again, this is a symptom I've seen reported several times, but I don't know enough about it to really point to the problem.

[eyemack]

The hand hum only occurs with TV on, and yes, it goes away when I touch the strings with my left hand. It also only really occurs with the JM as can be seen from figures below.

I spent some time this morning - as you do - measuring the noise level in the room for different guitars with TV on and off.

All amps off, ambient noise 34dB.

TV off, clean amp - Tele 38dB, Strat 37dB, JM 38dB, Vintage V100 LP copy 36dB (hand near pickup makes no difference to levels)

TV on, clean amp - Tele 42dB, Strat 40dB, JM 42dB (hand not near pickup) and 48dB (hand near pickup), LP copy 38dB. Hand position makes no difference with Tele, Strat or LP copy.

The only number that looks unexpected is the jump from the JM when hand is near pickup if TV is on. Despite what I said before, I think this must relate to the shielding process that I did yesterday.

[alexpigment]

It may be related to the shielding job, but I don't think there's anything inherent about shielding that causes this. In other words, I don't think you have to choose between one or the other. I took 3 of my JMs and put them about a foot in front of my Samsung LCD TV (a QLED, if that makes any difference) and could not get the problem to happen. I did test this without my hands on the strings, as you confirmed the issue doesn't happen if one hand is touching the strings.

There are a few factors I can't replicate. First, I don't have an American Pro II, and the pickups and wiring are indeed very different from a standard JM. The bridge pickup in particular has a switchable coil tap that I don't have on any of my guitars. Secondly, I don't have your specific TV, which may or may not be important. Lastly, I don't have your house. That last part may seem very pointless, but noise is always extremely location dependent. Everywhere in *my* house I have a digital morse-code-like sound that comes in through my guitars in certain directions (even with a battery powered amp), and this is the reason I've had to invest so much of my time experimenting with noise reduction/cancellation techniques in my guitars. Hell, right now that noise is happening because my guitar cable is sitting on the floor and my overdrive is still on. When I hear guitar demos of single coil guitars, I'm always a little frustrated that these people on YouTube are so lucky with the low noise levels in their environments.

With that mini-rant out of the way, figuring out stuff like this involves just taking out variables until (hopefully) the problem stops happening. A Captain Obvious statement for sure, but some things may not be intuitive to try. Taking off the pickguard and setting it aside is actually a helpful test, as it accomplishes quite a few things at once, and depending on the wire length, may be really easy to test. On the other hand, you could unmount your pickups from the guitar and see if that has any effect. Lastly, if you haven't eliminated everything from your signal chain except a cable straight from the guitar to a battery-powered amp (it wasn't clear if you were still running any effects in your previous test), I would do that first.

[eyemack]

As always, I really appreciate the time you are taking to help me here.

I took the JM and one of my amps to another room where my main TV is. No hum whatsoever, so I guess this annoying issue is largely down to the model of TV in my playing room. Oh well, I guess I will just live with it and appreciate that the shielding has certainly helped the issue.