Buzzing on contact

Hello,

I’m building a TL-1 kit and have seem to run into a problem with the electronics.

Once I soldered it all and assembled with strings, I plugged it in to test it. The moment I touched the strings, it buzzes. It sounds just like the standard electrical hum but it is much louder. It buzzes when I touch the strings, bridge and control panel (except when I touch the knobs).

Here’s some pictures of the wiring (there are extra wires as we grounded the bridge and the switch/control panel, which is the little brass bit, to the pots)

Attachment 31920 Attachment 31921
Attachment 31922 Attachment 31923

Can anyone see any errors or problems? All the bits came from pitbull but it still could be the bits.


Cheers,

Dylan

Hi mate. It's an earth problem in one or two places. First, check the bridge earth for a good, clean contact. Second, copper tape the back of the control panel and control cavity so that the tape touches and completely shields the electronics. Don't let the screws touch the tape though. Did you tape the pickup cavities too? See how that goes then check for any dodgy earth connections elsewhere. Hope it helps.

Hi ILR,

I have earthed the bridge two different ways. First I stuck a wire through the little hole under it and spread the copper under the bridge (it didn’t help). It is now earthed from a nut on one of the pickup screws, both were connected to the volume pot.

Yes I have taped all of the cavities but I haven’t done the panel. Can I only get it from pitbull or can I get it elsewhere?

Thanks for the tip, I’ll try shielding it and I’ll look for dodgy connections.

IIRC but probably have not...

I think this happened and it was the positive and earth leads arse-about on the input jack.

cheers, Mark.

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Second, copper tape the back of the control panel and control cavity so that the tape touches and completely shields the electronics. Don't let the screws touch the tape though.

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Why???
I intentionally run the tape so that the control plate screw makes contact with the shielding tape. Also with a metal control plate there's no need to put copper tape on the back. The control plate itself is conductive and forms the top of the Faraday Cage. When I do a continuity test with my multimeter, I can trace every metal piece (within the circuit) to a single ground point.


The fact that it's buzzing when the strings are touched (not the other way around) sounds like a reverse ground.
Have you checked that the input jack isn't wired backwards?

TBH, I'm having difficulty tracing exactly where the wires come from and where they're going in those photos. This kind of issue can also be caused by a cold solder joint (not fully soldered/connected) and they can be practically invisible to the naked eye, but wreak havoc with a signal path.

I would suggest checking the input jack first and, at the risk of sounding like an a-hole, some of those solder joins could stand redoing. Possibly de-soldering/re-soldering everything just be sure.
If you have a multimeter (a wise investment if you don't) continuity check each connection as you go and keep testing ground.

Get your shielding tape from The Big Green Shed gardening section, it's called Snail & Slug Barrier Tape.

It has the same adhesive back and electrical properties as the stuff labeled guitar shielding tape, just not as wide but plenty wide enough for what we are doing

Thanks to everyone for the tips, before eating dinner I re-soldered everything over (don’t worry McCreed, no a-hole vibes) but that didn’t fix it so after I switched the jack wires.

This seems to have fixed it. No extra noise when touching the bridge or control panel.

The next step for tomorrow will be stringing it up and testing it on a reliable amp this time. I’ve just discovered my testing amp has been playing up and isn’t working properly but luckily my line 6 amp (sorry tone purists) is fine.

Thanks for the help and I’ll post an update tomorrow sometime.

Cheers,
Dylan

Good result Dylan! Keep us posted.

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Get your shielding tape from The Big Green Shed gardening section, it's called Snail & Slug Barrier Tape.

It has the same adhesive back and electrical properties as the stuff labeled guitar shielding tape, just not as wide but plenty wide enough for what we are doing

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I've not used the BGS stuff, but I'd be very surprised if it has conductive adhesive. That's why good quality shielding tape costs more.

It's not that you can't use the snail & slug stuff, or any copper foil without conductive adhesive, but it means you have to place a drop of solder on every overlapping seam in order to attain complete continuity. Continuity is absolutely essential to creating an effective "shield".

Personally I prefer to pay the extra for the foil with conductive adhesive because some jobs can end up with a lot of overlap and soldering them all takes more time than it's worth to me.

The multi meter suggested it had good connectivity but having said that I solder the overlaps and also solder earth wires to it.

Belt & braces solution

T

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he multi meter suggested it had good connectivity but having said that I solder the overlaps and also solder earth wires to it.

Belt & braces solution

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Yeah, that'll get it done!
Just for curiosity, if you have some tape left, stick a couple of pieces overlapped on a bit wood and check it with the meter.
It would be interesting to know what you find.