pickup resistance tests good, magnet good, output super low?

[onusx]

i have a 70s guild humbucker in right now that got some issues; it's wired with a separate wire coming from each coil, two conductor with shield wired to ground at the baseplate. essentially seems like a four conductor wiring, but when wired up the pickup is really low output, noisy, and thin compared to the matching humbucker in the bridge.

each coil reads about 3.5k resistance. the magnet strength is good. when wired with coils in series, total resistance is just about 7k, a hair under. i've tried several different ways of making the series connection for the pickup, and also wired the pickup directly to the output jack to take the other controls out of the equation with the guitar.

any thoughts on what i could be looking at? if i were seeing a significantly different resistance reading i'd think the pickup was opening or shorting, but it seems like everything is in the correct range, and i'm not sure where the issue really is at this point. it does look like it was rewound or at least toyed with at some point-- there are trimmed leads at the solder tab on the baseplate-- but i don't know any details. because i don't know what's going on w/ the pickup internally, i don't even know which wires (there are white and red off each coil) are the start and end positions for each coil, or if they're flipped...

any help appreciated

brian

[Possum]

...

Check the wiring that connects to the pickup. I just repaired a set of TTops with the same complaint, the leads were shot, had several splices along their length that were really badly done. Sounds like a bad connection possibly.

[jason lollar]

possum is right- probably 8 years ago maybe I started checking everything with an inductance meter and you will occasionally see the DC resistance is what you expect but the henries or AC resistance will be off or the DC will be off quite a bit but the henries or AC will be right so I have seen over examining thousands of coils that the resistance can read correct but still have a bad coil- its almost always a bad solder joint.
Of course this would mean you have to chart your average resistance/ turns/ henries/ ac resistance for every type of pickup you make in order to spot a problem.

[David Schwab]

...but when wired up the pickup is really low output, noisy, and thin compared to the matching humbucker in the bridge.

The two coils are out of phase with one another. The tip off is it no longer hum cancels and is thin sounding.

You need to reverse the two wires from one coil.

[Possum]

..

Good point. Way to check it is with a cheapo analog ohmeter that has a needle for reading. Most big hardware store chains and maybe even Radio Shack has them for ten bucks or so, the cheaper the better because you will never use them for anything else. Hook up the black probe to pickup ground and red to hot. Take a fat piece of steel and quickly push it down at the slug coil and watch which way the needle jumps. Do the same for the pole coil. If they both jump the same direction the pickup is in phase with itself, if one is different you got a problem

[Peter Naglitsch]

The two coils are out of phase with one another. The tip off is it no longer hum cancels and is thin sounding.

Exactly my thought. But I have never used the method Possum described to check. That was a new one for me. Great and simple. Thaks for sharing Dave. Only problem...now I have to get myself a analog multimeter

[Possum]

...

Yes but they are dirt cheap. I have one about the size of a pack of cigarettes that I bought for $8 brand new, its a piece of junk but very useful for phase testing. You can do the same test with a digital meter but its harder to see which way the numbers jump...

[RedHouse]

The two coils are out of phase with one another. The tip off is it no longer hum cancels and is thin sounding.

You need to reverse the two wires from one coil.

[mkat]

Yes but they are dirt cheap. I have one about the size of a pack of cigarettes that I bought for $8 brand new, its a piece of junk but very useful for phase testing. You can do the same test with a digital meter but its harder to see which way the numbers jump...

Thanks for that, prefer doing as much testing upfront before installing as possible.

[onusx]

wow thanks for all the help-- i think i had a little of both issues going on. my first thought was that the pickup was out of phase with itself, but i rewired the series connection between the coils every possible way with the same results-- except at one point i had even less output, and it was getting frustrating. i peeled the pickup to expose the splices for the leads and one of the solder joints was really ugly-- gray and dull, not happy. redoing the lead solved the issue.

great tip on the phase checking method with the MM, i'll have to try that. i'd checked the polarity of the polepieces, but not with the wires hooked up. i could've used this tip a couple of weeks ago with a wide-range humbucker i was working on. at some point someone had disassembled it and mixed up (or intentionally reversed?) the magnets, so that the coils were out of phase with themselves horizontally-- from low E to high E, there were 3 north and 3 south in one coil, (NNNSSS) and a mix in the other-- (N,N,S,S,N,S)... had me scratching my head for a minute

[madialex]

wow thanks for all the help-- i think i had a little of both issues going on. my first thought was that the pickup was out of phase with itself, but i rewired the series connection between the coils every possible way with the same results-- except at one point i had even less output, and it was getting frustrating. i peeled the pickup to expose the splices for the leads and one of the solder joints was really ugly-- gray and dull, not happy. redoing the lead solved the issue.

great tip on the phase checking method with the MM, i'll have to try that. i'd checked the polarity of the polepieces, but not with the wires hooked up. i could've used this tip a couple of weeks ago with a wide-range humbucker i was working on. at some point someone had disassembled it and mixed up (or intentionally reversed?) the magnets, so that the coils were out of phase with themselves horizontally-- from low E to high E, there were 3 north and 3 south in one coil, (NNNSSS) and a mix in the other-- (N,N,S,S,N,S)... had me scratching my head for a minute

I have seen this before too. Luckily all I had to do was look at the slugs, they didn't look right so upon taking the cover off I found the problem, put the mags back like they should be and it worked great.

[RedHouse]

...i peeled the pickup to expose the splices for the leads and one of the solder joints was really ugly-- gray and dull, not happy. redoing the lead solved the issue. ..

Yep, basic soldering skills will make you, or break you.