Jazzmaster Wiring Problem—Help!

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pheelup
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Jazzmaster Wiring Problem—Help!

Post by pheelup » Mon May 24, 2021 4:16 pm

Okay, so I’m having a problem with my Jazzmaster. I have a Squier VM Jazzmaster with a couple of upgrades. Everything was working just fine but this weekend I put in a Fender wiring harness, hooked it up to a custom painted pickguard, and installed some new pickups. I used copper conductive tape on the inside of the guitar and back of the pickguard. I hook everything up, check the pickups, and they work. But when I push the pickguard in place with the body—poof! Lead circuit goes silent. I’m not sure what to do. Thoughts?Image[/img]

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Re: Jazzmaster Wiring Problem—Help!

Post by schoolie » Mon May 24, 2021 5:33 pm

Maybe a wire/component is touching the shielding. To troubleshoot try insulating with something like a plastic shopping bag, and see if the problem goes away. YOu should be able to locate the problem.

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Re: Jazzmaster Wiring Problem—Help!

Post by andy_tchp » Mon May 24, 2021 6:33 pm

Output terminal from the three-way switch is probably shorting against the shielding tape.

There's almost no space in there.
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Re: Jazzmaster Wiring Problem—Help!

Post by charmonder » Mon May 24, 2021 8:05 pm

andy_tchp wrote:
Mon May 24, 2021 6:33 pm
Output terminal from the three-way switch is probably shorting against the shielding tape.

There's almost no space in there.
yup, its gotta be something like this, you can put an inch of painters tape* onto the shielding above the selector terminal and also the vol/tone pot lugs.



*or any normal non conductive tape

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Re: Jazzmaster Wiring Problem—Help!

Post by pheelup » Tue May 25, 2021 4:32 am

Thanks, guys--I'll check these suggestions out when I get home. Any other suggestions are appreciated because I'd REALLY like to hear these new pickups and finish setting this up and would prefer to do it myself.

Last night I figured the 3-way toggle was maybe hitting the shielding, but the issue happens if I push the pick guard against the body at different locations as well (while the 3 way toggle is not inside the body). I did have an aluminum shield on top of the copper tape on the pick guard and thought maybbbbe there was some issue with that (but couldn't understand HOW, but just troubleshooting). I took the aluminum shield off and same issue.

The pickguard is overlapping on the bridge thimbles a slight bit (I could file it down a little, probably made slightly smaller by the paint from where I painted the pick guard) would that cause an issue?

I'll try the painters tape suggestion tonight as well. Thanks guys!

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Re: Jazzmaster Wiring Problem—Help!

Post by pheelup » Tue May 25, 2021 4:36 am

https://ibb.co/zx1FMML
https://ibb.co/cgjj53f
https://ibb.co/4tMqm15
Pics before I took off the aluminum shield to see if I'm missing something

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Re: Jazzmaster Wiring Problem—Help!

Post by pheelup » Tue May 25, 2021 4:41 am

schoolie wrote:
Mon May 24, 2021 5:33 pm
Maybe a wire/component is touching the shielding. To troubleshoot try insulating with something like a plastic shopping bag, and see if the problem goes away. YOu should be able to locate the problem.
Just to make sure I'm understanding, so like put a piece of shopping bag between the volume pots (selector switch, etc) and the shielded pick guard?

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Re: Jazzmaster Wiring Problem—Help!

Post by schoolie » Tue May 25, 2021 5:10 am

pheelup wrote:
Tue May 25, 2021 4:41 am
schoolie wrote:
Mon May 24, 2021 5:33 pm
Maybe a wire/component is touching the shielding. To troubleshoot try insulating with something like a plastic shopping bag, and see if the problem goes away. YOu should be able to locate the problem.
Just to make sure I'm understanding, so like put a piece of shopping bag between the volume pots (selector switch, etc) and the shielded pick guard?
I meant insulating between the pots, caps, input jack,..., and the copper tape in the shielding cavity. You can use anything, like masking tape, sandwich bags etc. I thought something might be touching the cavity sheilding.,,,Check the rhythm circuit cavity too..

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Re: Jazzmaster Wiring Problem—Help!

Post by pheelup » Tue May 25, 2021 5:34 am

schoolie wrote:
Tue May 25, 2021 5:10 am
pheelup wrote:
Tue May 25, 2021 4:41 am
schoolie wrote:
Mon May 24, 2021 5:33 pm
Maybe a wire/component is touching the shielding. To troubleshoot try insulating with something like a plastic shopping bag, and see if the problem goes away. YOu should be able to locate the problem.
Just to make sure I'm understanding, so like put a piece of shopping bag between the volume pots (selector switch, etc) and the shielded pick guard?
I meant insulating between the pots, caps, input jack,..., and the copper tape in the shielding cavity. You can use anything, like masking tape, sandwich bags etc. I thought something might be touching the cavity sheilding.,,,Check the rhythm circuit cavity too..
Sounds good--thanks!

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Re: Jazzmaster Wiring Problem—Help!

Post by timtam » Tue May 25, 2021 7:22 pm

You might get away with no shorts when adding grounded shielding to guitars with few controls and few exposed terminals near to the shielding. But on a JM or jag with many controls and cramped cavities, the chance of shorts is much higher. I protect every single terminal on switches and pots with heatshrink, and also cover capacitor legs. Even without considering shorts to the shielding, short lengths of exposed wire on close adjacent terminals of switches and pots can be squashed together and shorted. Wiring on production guitars was shoddy in the 1950s and hasn't changed much since then. But there's no reason why you can't use what is now standard electronic wiring practice. And let's not even mention Gibson's continued use of long uninsulated braided shield on pickups !

I'm not a big fan of paying for expensive pre-wired harnesses, but if you do you should expect heatshrink-ed connections for your money, like on this Rothstein harness. The bare unused terminals could also be protected if they are near to grounded shielding.
Image
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Re: Jazzmaster Wiring Problem—Help!

Post by pheelup » Wed May 26, 2021 5:17 pm

Okay, so I tried putting painters tape under the pots, selector switch, and jack. I put some painters tape around where the selector switch and jack might make contact with the copper tape in the body. I did find some excess solder on the selector switch (removed that, it was under the three wires and the two metal tabs were soldered together, now they are not), still same problem. Here’s a video. When the plate makes contact with the shielding it goes dead. Move it to rhythm mode, neck pickup works fine. So—should I remove the shielding? Should I buy a new selector switch? Does something else look wrong (I show the guts and whatnot in the video). Please any help would be greatly appreciated! https://youtu.be/ofASU7XKJF8

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Re: Jazzmaster Wiring Problem—Help!

Post by charmonder » Thu May 27, 2021 6:53 am

pheelup wrote:
Wed May 26, 2021 5:17 pm
Okay, so I tried putting painters tape under the pots, selector switch, and jack. I put some painters tape around where the selector switch and jack might make contact with the copper tape in the body. I did find some excess solder on the selector switch (removed that, it was under the three wires and the two metal tabs were soldered together, now they are not), still same problem. Here’s a video. When the plate makes contact with the shielding it goes dead. Move it to rhythm mode, neck pickup works fine. So—should I remove the shielding? Should I buy a new selector switch? Does something else look wrong (I show the guts and whatnot in the video). Please any help would be greatly appreciated! https://youtu.be/ofASU7XKJF8
the fact that the rhythm circuit works is a major clue!

I would put tape under this part
Image

and then maybe point the pots at each other so the lugs arent touching the side

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Re: Jazzmaster Wiring Problem—Help!

Post by timtam » Thu May 27, 2021 7:24 am

The only thing that looks "wrong" to me is all the bare terminals/wire on the controls. The fact that the rhythm circuit is OK and the lead circuit cuts out when you press down near the lead controls suggests that one of the hot terminals (or the bare wire at those terminals) is coming into contact with the cavity grounded shielding, most likely the cavity floor. A multimeter across the output jack terminals (eg tip and and shaft on jack at opposite end of guitar cable) would confirm a short to ground. If so I would simulate heatshrink by wrapping every bare wire/terminal near/on those controls with electrical tape.

You could also measure the depth of your cavities and target the pot/switch/jack that extends to the greatest depth. It's also worth rotating your pots so that the terminals all face inwards, towards the other pot; that reduces the chances of their terminals contacting the cavity side walls.

It's still possible that pushing down is creating the contact/short in another component rather than the lead circuit pots, so the more bare terminals you insulate the more likely you are to fix the problem. The lead circuit wiring extends all the way from the rhythm/lead switch to the output jack. Leaf-style pickup toggle switches are problematic in that there is a lot of exposed metal carrying pickup hot signals. But the switch's extremities are obviously the parts most likely to make contact with the grounded cavity walls/floor. If the pressing down signal loss effect is there regardless of the toggle switch (pickup) selection I would tend to think the switch itself is fine and shorting is not occurring at the switch.

If wrapping terminals/bare wire solves the problem, then I would then replace all the tape with proper heatshrink. So there are no exposed terminals/wire to get shorted to the shielding.
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Re: Jazzmaster Wiring Problem—Help!

Post by bjornsynneby » Fri May 28, 2021 10:27 pm

Maybe I’m mistaken but you seem not to have a ground wire between vol and tone pot. That way you rely on the shielding to transfer the ground current between them. So somewhere between these two pots there might be bad continuity. Either between one pot and the shield or in the shield. So when you press the sound goes away right?

The solution to this is to solder a ground connection between the pots. (Or put star washers under the components that transfer ground through the shield. )

To put heat shrink on the connections is also a very good idea. It will decrease the risk of short cuts. You have built a tight cage of ground connection around your wiring. And this cage is threatening to short cut hot connections when you push the pick guard.

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Re: Jazzmaster Wiring Problem—Help!

Post by bjornsynneby » Wed Jun 02, 2021 11:48 am

I can not see ground connections from the pickups, rythm volume pot, toggle switch or between lead pots. The rythm bracket is the only component that I can see is not isolated in your video. Could it be that the only way the bracket could return ground current is when the cavity shield comes in mechanical contact with the pickguard shield? And that this ground current in some mysterious way reaches the output jack sleeve from the cavity shield...? There is a black wire soldered to the lead circuit tone pot chassie. Is that connected to the cavity shield perhaps?

If that is the case and there is no ground current between lead pots the only way the guitar can make sounds other than buzz is when pressing the two shields together.

I would add ground connections between lead circuit pots and from the rhytm volume pot. Like in the wiring schedule for the classic sixties jazzmaster. Do not put to much trust in a taped shield to transfer ground current. At least not when you isolated the components. ;)

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