How to troubleshoot wiring with a multi meter?

[BeKindRewind]

I've got a pickguard for my Strat that's not working and I can't figure out why.. it's been out of the guitar for a year or two, and what might've happened is a wire got knocked loose or something, I really don't know.

It's a pretty complicated setup, or else I might be able to figure it out, but here's what it is:

3 Quarter pounders, the mid/neck are tap versions.

Volume pot and 2 push pull tone pots.

Middle push pull does the taps, and the other push pull was wired to do a phase switch on the middle pickup. So it's a lot more complicated wiring than what I'm used to. The pickguard was actually custom made for me by Orpheo (thanks, man!) and I'd love to get it working again. When I wired it up, tapped the pickups with screwdrivers it made some noises so I thought it was working, but when I put strings on to test, it's nothing but noise. Noise gets quieter when I touch the output jack plate also for some reason.

If someone could guide me how to use my multimeter to pinpoint the issue, I'd be so grateful. Hell it could even be the output jack im just not sure the procedure for how to pinpoint it?

I can post pictures of the wiring or try drawing a diagram of it if that would help.

 

[jeremy]

if you plug a cable into the jack, turn all the controls full up, you can put the meter on the tip and sleeve and measure dc resistance for each setting. are you getting nothing from any switch setting?

 

[BeKindRewind]

if you plug a cable into the jack, turn all the controls full up, you can put the meter on the tip and sleeve and measure dc resistance for each setting. are you getting nothing from any switch setting?

Thanks, so no, no audible signal from any setting, there's just a howling noise that stops if I touch the output jack plate, but that noise does seem to be affected by turning the tone knobs, and if I turn the volume pot all the way off, the noise stops too.

What I did try before wiring it up was I put the meter on the output and back of the volume pot and it gave a reading that went up and down as i turned the pot. so I said okay great, it's outputting just fine.

When I get time later tonight I'll try what you said and report back.

 

[ehdwuld]

Jack wired backwards

 

[BeKindRewind]

Jack wired backwards

:haha: Actually yeah, good spot, that's correct, I swapped the 2 wires on the output jack and now the guitar is working. Thanks guys!

but I have a host of other problems I could use a hand with :sad:



1) The most important is that there's a little bit of a crackling noise over everything. it's not RF Single coil hum, because the in between positions don't help. noise gate stops it when i'm not playing, but you can hear it when I am

2) The neck pickup coil tap doesn't work. pickup reads 13.65 no matter what the position of the middle push\pull. it does work on the middle pickup, cutting it down to about 6.8k. I am pretty sure it was like this when I got it, but I never bothered to look into how to correct this

3) The entire middle pickup will cut out pretty frequently, especially when using one of the push\pulls, and then if I tap on and around the bridge tone control I can get it to work again. sometimes the entire pickguard cuts out and sometimes it's only the middle pickup

4) the weirdest one is this : the coil tap push\pull reverses the phase switch push\pull. for example if I'm on position 4 playing with the phase switch pulled so that I'm out of phase, but then I hit the coil tap switch , the pickups are suddenly IN phase, but if I push the phase switch back in, they're out of phase again. I'm not sure if there's a way to fix this or if it's just a limitation, but it's unfortunate


I'm not sure what to do here, how to troubleshoot it , or if it makes more sense to just to try and start from scratch with a wiring diagram or what. i'm halfway tempted to just take the easy road and put the plug n play EMGs back in this, but I really love Quarter Pounds

 

[BeKindRewind]

pics of the wiring: Wiring - Imgur​

 

[ehdwuld]

1. Bad solderr joint probably a ground
Touch them all with a hot iron until the solder reflow

2. Coil tap should have the coild connection (red/white pair for duncans) to the center lug on the switch then either the hot to the upper or the ground to the upper depending on which coil you want active in the split

3. Bad solder joint on the switch

4. Miss wired switches