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Boffins, what the hell is making my guitar do this?

Posted: Wed Aug 19, 2015 7:00 pm
by zom-zom_Archive
Are you certain the ground wire at the tailpiece is making good contact?I had an SG that did some really weird stuff as a result of a faulty ground, touching random pickguard screws would make static and such.

Boffins, what the hell is making my guitar do this?

Posted: Thu Aug 20, 2015 7:00 pm
by honeyisfunny_Archive
tallchris wrote:Are your nads wired in phase?My plums are so far out of phase they've gone all the round and are back in again. It would be remarkable if it turned out my testes cause interference with P90 pickups. Not ruling it out.

Boffins, what the hell is making my guitar do this?

Posted: Thu Aug 20, 2015 7:00 pm
by Speedie_Archive
Manscape or full bush? There's static issues to consider.

Boffins, what the hell is making my guitar do this?

Posted: Fri Mar 22, 2019 7:00 pm
by Adam P_Archive
I d bite the bullet and de-solder the lead from each pickup from its respective volume pot and take measurements. That way you can be sure the electronics aren t interacting with your readings.

Boffins, what the hell is making my guitar do this?

Posted: Fri Mar 22, 2019 7:00 pm
by endofanera_Archive
MatthewK wrote:With the neck pickup selected it's 12kΩ, neck and bridge 11.8kΩ, but bridge alone shows 400kΩ. I haven't seen exactly this, but whenever I see these types of issues I always look at those damned pickup selector switches first. Clean it, exercise it, make sure it's making good contact in all three positions etc. After I do that if it still isn't doing what I want then checking solder connections may make sense, but those pickup selector switches are a regular weak link.

Boffins, what the hell is making my guitar do this?

Posted: Fri Mar 22, 2019 7:00 pm
by MatthewK_Archive
This seemed like the best thread to ask in. I recently bought a 1975 Greco Tele Deluxe copy with humbuckers and the same wiring setup as the original. The seller told me there was a problem with the bridge pickup sounding thin and maybe there was a short in it or something. I love the guitar and the pickups so I am about to try and fix it - I've some experience soldering broken windings etc so I think I have a shot.However in trying to diagnose the issue I connected a multimeter across the output jack and measured DC resistance of everything-in-circuit, all pots on 10. With the neck pickup selected it's 12kΩ, neck and bridge 11.8kΩ, but bridge alone shows 400kΩ. The pickup makes about half the volume of the other one, but I have tapped the polepieces with a screwdriver and both pickups are active for the right positions of the switch. The volume and tone pots are 500k and the tone pot is fed via a capacitor from the top of the volume pot; a ground wire connects all four cans to the pickup grounds. All volume and tone controls work as intended.I also have ground continuity between the pickup covers, bridge, switch washer and output jack.Has anyone seen this situation, before I go unsoldering things and trying to open the pickup?Crappy photos from a few weeks ago, attached.

Boffins, what the hell is making my guitar do this?

Posted: Mon Mar 25, 2019 7:00 pm
by Tommy_Archive
Adam P wrote:I d bite the bullet and de-solder the lead from each pickup from its respective volume pot and take measurements. That way you can be sure the electronics aren t interacting with your readings.This. I think you can get away with just desoldering the hot leads to compare the two pickups. They should read close to each other. If one pickup is reading Also, 400k?! If there was a short in the coil wouldn't it read low, not crazy high? maybe an issue with the volume pot on the bridge pickup?

Boffins, what the hell is making my guitar do this?

Posted: Tue Mar 26, 2019 7:00 pm
by Adam P_Archive
The 400k reading has to be an interaction with the volume and tone controls. The only thing concerning to me is that the pickup *should* be the lowest of the three impedances (assuming the tone control is set so that the resistance isn t minimum), and when you parallel impedances the resulting equivalent is always less than the smallest individual value. But these are complex (mathematically) and I m sleep-deprived so I may not be thinking clearly.

Boffins, what the hell is making my guitar do this?

Posted: Tue Mar 26, 2019 7:00 pm
by MatthewK_Archive
I thought maybe a capacitor might be in series somehow or the pickup is broken in such a way that it s capacitive, so the DC reading is open circuit but it still works.