Wired my First Jazzmaster Today

[j mascis]

This is one I built with WRHB pickups (hot and ground, two leads).

So everything turned out well and the guitar sounds great, except it has intermittent crackling/popping noises.
It happens sometimes when the pick hits the string, so this suggests a bad ground, no?

Also, in the rhythm circuit I put two genuine fender 1meg pots (part 005-4457-049). What is strange is when I turn down the volume I still hear sound. Are these pots specific to volume and tone or can they be used interchangeably? It seems like the problem might be in this circuit, but I'm hearing the crackling/popping even in the other circuit.

I know it's vague, but does anyone have ideas? I have to open her up again, which sucks...

[Pepe Silvia]

I thought J Mascis hated humbuckers...

[terminalvertigo]

I think it's rad that OP is letting J take it on tour!

[timtam]

So you used two mini 1meg linear pots in the rhythm circuit, rather than one 50k tone and one 1meg volume ? Assuming that's what you meant to do, they're interchangeable. But the way they are connected in the rhythm circuit is different (ie volume comes off the wiper of the tone pot) to how they are connected in the lead circuit, which is more like a conventional volume / tone circuit. So it's possible that is part of why you're getting unusual behaviour/interaction. Is the tone control working ? Sometimes missing grounds at tone pot / cap / volume pot can cause odd behaviour. Anything else about your wiring that is different ?

Crackling / popping is often a static electricity issue, unless you mean when you use the pots. I've never had that issue, but tumble-dryer anti-static sheets rubbed on the pickguard are a common recommended fix if your environment/guitar are prone to the problem. I assume your multimeter shows continuity between the strings and the rim (ground) of the output jack ?

[j mascis]

So you used two mini 1meg linear pots in the rhythm circuit, rather than one 50k tone and one 1meg volume ? Assuming that's what you meant to do, they're interchangeable. But the way they are connected in the rhythm circuit is different (ie volume comes off the wiper of the tone pot) to how they are connected in the lead circuit, which is more like a conventional volume / tone circuit. So it's possible that is part of why you're getting unusual behaviour/interaction. Is the tone control working ? Sometimes missing grounds at tone pot / cap / volume pot can cause odd behaviour. Anything else about your wiring that is different ?

Hey thanks for the detailed response. Yes two mini 1 meg pots - my thinking was I could make that circuit more usable that way.

The multimeter shows everything as grounded. I checked each connection as I made it, too. I do feel it's a problem in the rhythm circuit. The tone control seems to work in that circuit, but volume also seems to roll off tone (and also reduces volume, but not to zero). How is the capacitor in that circuit grounded? My diagram I think had the legs of it going in a lug on one pot and a lug on the other, rather than being grounded to the back of one like on the main circuit. I'm starting to think this might be the issue.

Crackling / popping is often a static electricity issue, unless you mean when you use the pots. I've never had that issue, but tumble-dryer anti-static sheets rubbed on the pickguard are a common recommended fix if your environment/guitar are prone to the problem. I assume your multimeter shows continuity between the strings and the rim (ground) of the output jack ?

Interesting. I put copper shielding in the body, but I didn't put it on the pickguard after thinking about it more and figuring humbuckers didn't really need it. I wonder if this is causing a static problem.

[timtam]

I do feel it's a problem in the rhythm circuit. The tone control seems to work in that circuit, but volume also seems to roll off tone (and also reduces volume, but not to zero). How is the capacitor in that circuit grounded? My diagram I think had the legs of it going in a lug on one pot and a lug on the other, rather than being grounded to the back of one like on the main circuit. I'm starting to think this might be the issue.

The volume pot tab and the end of the cap are usually grounded together, as shown here. But it's one of those little connections that is almost hidden - you'll miss it if you don't know that it must be there somewhere. The black wire is a ground wire that grounds the roller plate/pot bodies, and then there's a little grey wire from there to the bottom tab of the volume control, where the cap also attaches. Another tip for that area is to cover the cap legs with insulation, so that there's no chance of them shorting to hot or ground when it's all closed up. I would also usually put heatshrink over all the pot tabs and switch tabs too.

[j mascis]

The volume pot tab and the end of the cap are usually grounded together, as shown here. But it's one of those little connections that is almost hidden - you'll miss it if you don't know that it must be there somewhere. The black wire is a ground wire that grounds the roller plate/pot bodies, and then there's a little grey wire from there to the bottom tab of the volume control, where the cap also attaches. Another tip for that area is to cover the cap legs with insulation, so that there's no chance of them shorting to hot or ground when it's all closed up. I would also usually put heatshrink over all the pot tabs and switch tabs too.

Thanks! It has to be that rhythm pot being ungrounded. That diagram you have looks much better than mine. Any way you can link it or PM me that one?

Do you think not putting copper tape on the pickguard (mentioned in the prior post) is causing static? Or do you think just grounding that rhythm circuit will solve both issues?

[timtam]

The diagram is from the AV65 ....
https://www.fmicassets.com/Damroot/Orig ... A_SISD.pdf
It uses the brass plates as common ground locations. The Vintera doesn't have those plates so uses a different more generalizable approach ...
https://www.fmicassets.com/Damroot/Orig ... 1_2019.pdf

I haven't dealt with the static electricity generation problem before - only heard about it. But assuming that's what yours is, it would seem logical that attaching a grounded shield to the pickguard might help it. I would probably sort out the rhythm circuit problem first, just so you know which solution solves which problem.

[Bradley-Jazz]

I have had the static issue - on a Les Paul Special and SG where the scratch plate doesn't connect with anything electrical, and on teles where there was little contact with grounded electrical components. The tumble drier sheets work well, but need reapplying/wiping regularly. The teles were fixed by shielding the back of the plate with copper foil, and making sure there was a good electrical contact with the control plate (via another strip of foil under both). Not much to be done about the Gibsons! I've never had this problem on my offsets which either already had foil shielding or aluminium shielding plates.

Shielding the scratch plate is cheap and easy so worth doing anyway? Make sure there is good continuity to ground (usually bolting the pots to the plate takes care of this).

I do agree with TimTam about dealing with one problem at a time though!

[j mascis]

Cool thanks guys. Think I can figure it out now with this info. Those diagrams are great.
One thing I don't understand is in the 60s wiring diagram, why can't the mini volume pop just be grounded to the tone pot next to it? Instead they run it all the way to the main circuit volume pot. Would it create a ground loop to ground it on the mini tone pot?

[Bradley-Jazz]

If you mean grounding to the pot case, the rhythm tone doesn't have one in that diagram, not soldered on anyway. The cases of both rhythm pots are connected via the metal bracket, and there needs to be a connection from that assembly back to the ground connection to the jack sleeve, which on that layout is via the lead circuit vol pot.

[timtam]

Cool thanks guys. Think I can figure it out now with this info. Those diagrams are great.
One thing I don't understand is in the 60s wiring diagram, why can't the mini volume pop just be grounded to the tone pot next to it? Instead they run it all the way to the main circuit volume pot. Would it create a ground loop to ground it on the mini tone pot?

The mini tone pot is not grounded without that long ground wire - it grounds the roller bracket, which then means anything conductive attached to it is grounded ... the bodies of the two mini pots. But then the actual circuit also requires that the bottom tab of the volume pot needs grounding - hence the small grey connection from the bracket ground to the bottom tab (and the tone cap).

There's only one ground potential in a guitar, so you can can have physical ground loops if you want .. no hum-producing current can flow in them (because of the lack of a potential difference between different ground points), so it's not a problem. 'Star' (single common-point) grounding can still be pursued for neatness sake though, as Fender has done in the Vintera (sometimes confounded by a huge bulbous solder monstrosity on the back on the main volume pot - use a screw-terminal common ground point in the cavity floor instead).

[j mascis]

Ah! Got it, thanks.

One more question. My '65 AVRI has rubber pads attached to the pickguard, and they help the black roller knobs in the rhythm circuit move smoothly. Anyone know where I can buy those? They are moving roughly without those.

[j mascis]

So I was able to get it soldered up, and the multimeter is showing all is good.
The only issue is that it was hard to get the solder to stick to the bracket in the rhythm circuit. I'm a bit concerned that it will break off.

[HarlowTheFish]

So I was able to get it soldered up, and the multimeter is showing all is good.
The only issue is that it was hard to get the solder to stick to the bracket in the rhythm circuit. I'm a bit concerned that it will break off.

Find a corner of it you want to solder to and scratch it up a bit, it helps the solder stick.