Old Gibson T-Top pickup

[jP3]

Hi, new here.

I just got a 1977 Les Paul Custom. The bridge pickup is putting out a low signal. I put a new pickup in a it works fine, so it's not the electronics. The old pickup reads 7.6 resistance. Any idea what could be wrong the pickup and how to fix it?

Thanks in advance.

[Jim Darr]

Check two things

Assuming it was wired correctly before you took it out, I’d check two things:

1: Make sure the DC resistance doesn’t cut out or vary when you wiggle the wires. If it does, this is a sign of a short or loose connection in the pickup or lead wires from the pickup.

2: Check the magnet strength. A real simple test is to hold a ferrous object (like a metal screwdriver) to the pole pieces of the ”bad” T-Top and compare the magnetic strength to the good pickup. If the magnet lost it’s strength, you can have it remagnetized by contacting a pickup maker that offers a remagnetizing service.

Good Luck

Jim

[jP3]

Thanks for the tips, I will give them a try.

[Robert M. Martinelli]

Hi, new here.

I just got a 1977 Les Paul Custom. The bridge pickup is putting out a low signal. I put a new pickup in a it works fine, so it's not the electronics. The old pickup reads 7.6 resistance. Any idea what could be wrong the pickup and how to fix it?

Thanks in advance.

Hi jp3,
7.6 resistance? Do you mean 7.6 Ohms or 7.6 KOhms? Readings without measuring units are useless.....

If your reading is 7.6 Ohms I would say you have a shorted pickup.... If it reads 7.6 KOhms then the winding is OK and your problem is probably related to a weakened magnet.

Hope this helps

Best regards

Bob

[jP3]

Hi,

7.6k Ohms. It looks like someone messed around with the pickup before. They re-soldered the two white finish wires and shoved them in close to the hookup wire without any tape or shrink tubing to protect it. IF I would wiggle the wires around they would touch and short out and the reading would drop down to around 3k Ohms. I put some shrink tubing on the connection hopefully this was the problem. Before I re-install the pickup to see if it works I was going to try and re-magnetize the magnet myself, not sure it is necessary. The magnet seems to be as strong as the neck pickup's magnet. Would it be redundant to re-magnetize the magnet ? Or would it be a good idea since the pickup is 30+ years old?

Thanks,
John

[Dave Kerr]

You're looking for gross errors here, not fine tuning for tone, so I'd leave well enough alone if the magnet isn't noticably weaker than the other.

[Robert M. Martinelli]

+1.
If you fixed the problem with the leads, try to re-install the pickup and hear how it sounds, if it isn't noticeably weaker than the other one I would leave it alone too.

HTH

Best regards

Bob

[jP3]

I re-installed the pickup and it is still the same, very week. The resistance is even reading a little bit higher after I fixed the problem with the leads.

[Dave Kerr]

I'd wonder about this:

It looks like someone messed around with the pickup before. They re-soldered the two white finish wires and shoved them in close to the hookup wire without any tape or shrink tubing to protect it.

Are you sure that those two white wires are both the finish wire to the coil? I suspect an out of phase issue.

[Jim Darr]

+1
I agree …make sure the finish wrap of each coil is connected together. These should be the white leads from that era...but who knows if the one coil messed with our even rewound.

Jim

[jP3]

Not sure, it appears to be connected correctly. Hookup wire (inner Hot) connected to black lead wire (slug coil), other black lead (adjustable coil) soldered to baseplate for ground (braided hookup wire also soldered to baseplate). White finish leads from both coils soldered together.

[Robert M. Martinelli]

Well,
maybe you have an "out of phase" issue, maybe you don' t, anyway, to state this, I would temporarily split the coils sending the CT ( white+white ) to GND, thus using only one coil. Then test the other coil similarly by making the CT the "hot" terminal. If your output in "single coil" mode is higher with each coil ( and with more pronounced basses ) than the one you get with both the coils in series, then you indeed have a phase issue. If this is not the case, and each coil sounds weaker than the two coils in series ( which is normal ), then the phase is OK and my vote goes to a weakened magnet.

HTH

Best regards

Bob

[jP3]

Thanks, I will give that a try. Also the polarity of the adjustable coil is north up and the other coil is south up. Can anyone tell me how you remagnetize these. Do you do each coil separate? Both pickups are the same. The new pickup installed is reverse polarity of the originals and works fine.

[rbkxiiowe]

Hi all. New member here.

It isn't the coils that are magnetised - there is only one magnet in there, laid so that the north touches one coil's pole pieces and the south touches the other coil's pole pieces. Search Google Images for "gibson humbucker patent".

I agree with the others here - don't mess with the magnet until you've exhausted all the other possible faults. It does sound like the coils have probably been connected out of phase.

[jP3]

Well....I have connected each coil independently and they each sound about the same (weak). Is there another test I should try? I have repair magnets from Stewart Mac, my question if you slide the pickup between the magnets like they show on the Stewart Mac website won't both coils be either north up or south up? How would you get one coil north up and one coil south up? Would you take the magnet out and re-magnetize it, half of the magnet is north up and half south up.

Thanks