1979 LP Custom - Neck Pickup Hum

[ngjenkins]

Hey all, been researching this for a month and finally decided to set up an account and try my luck here.

I have a 79 LP Custom and I recently swapped out the pickups for a 490/498 set. I also swapped out the pots for Sweetwater's Emerson prewired set. The pickups sound great. Perfect for what I play (a lot of 90s rock/metal, Alice in Chains, STP, Metallica, etc...) but there's a problem and the tech I worked with is stumped as well.

With any gain, the neck pickup buzzes like a single coil. If I touch the metal tip of the pickup selector, the buzz greatly decreases.

Basically, we've gone through all the wiring and it all APPEARS correct. Do I maybe have a bad pickup (got it used on Reverb)? Or is there some weird grounding thing we've done wrong because Norlin era wiring is weird.

Would love your thoughts.

Thanks,

Nick

 

[ADP]

A 1979 Les Paul Custom has a unique grounding system that isn't connected to the strings. Unless preserving the "clamshell" grounding unit for vintage purposes - it is best to convert to 50's style wiring with a ground connected to the bridge post. You can use a screw through in the cavity to reach the bridge and make contact, that is easiest. Also upgrade to VIP pots (Vintage Inspired Pickups) while you're at it.

 

[ngjenkins]

A 1979 Les Paul Custom has a unique grounding system that isn't connected to the strings. Unless preserving the "clamshell" grounding unit for vintage purposes - it is best to convert to 50's style wiring with a ground connected to the bridge post. You can use a screw through in the cavity to reach the bridge and make contact, that is easiest. Also upgrade to VIP pots (Vintage Inspired Pickups) while you're at it.

Thank you! I'll talk to the tech about this. He really didn't want to drill into the body, but this doesn't sound that bad.

 

[dnabbet2]

I'm not being contrary, and I defer to greater expertise, but I've got the "tuna tin" cover over the controls as well as around the pickup switch and the output jack of a 1980 Standard 80 -- plus the covers on the pickups -- and with no string ground, it is absolutely noiseless. And I prefer not having a string ground for safety reasons, though I know this latter has been hotly debated.

 

[ngjenkins]

I'm not being contrary, and I defer to greater expertise, but I've got the "tuna tin" cover over the controls as well as around the pickup switch and the output jack of a 1980 Standard 80 -- plus the covers on the pickups -- and with no string ground, it is absolutely noiseless. And I prefer not having a string ground for safety reasons, though I know this latter has been hotly debated.

The neck pickup is uncovered so I'm going to FIRST try taking the cover off the old T-Top and put it on the new pickup. Maybe that'll help.

 

[PaulD]

I know this latter has been hotly debated.

There is nothing whatsoever to debate about. From a technical point of view it is undoubtedly safer if the strings are not grounded, if they aren't connected to anything then there are no circumstances under which they can become live and shock you if you touch something that is grounded. In reality the risk is minimal and provided that the rest of your equipment is in good order and properly grounded (any vintage amplifiers MUST be fitted with a properly wired 3 core mains cable) then any risk is negated.

Norlin era guitars did not have the strings grounded and relied on shielding to prevent RF and EMF noise. If any of this shielding is missing, i.e. pickup covers and / or the metal shielding can in the control cavity then they will likely be noisy.

 

[ngjenkins]

There is nothing whatsoever to debate about. From a technical point of view it is undoubtedly safer if the strings are not grounded, if they aren't connected to anything then there are no circumstances under which they can become live and shock you if you touch something that is grounded. In reality the risk is minimal and provided that the rest of your equipment is in good order and properly grounded (any vintage amplifiers MUST be fitted with a properly wired 3 core mains cable) then any risk is negated.

Norlin era guitars did not have the strings grounded and relied on shielding to prevent RF and EMF noise. If any of this shielding is missing, i.e. pickup covers and / or the metal shielding can in the control cavity then they will likely be noisy.

I think I'm going to take the 490 out of the neck and put the T Top back in (as it's covered) and see what that sounds like. I really want the saturation with the bridge pickup that the T Top just didn't have. So the neck is free to kind of be whatever it wants to be, haha.

 

[ADP]

Stock is always best. But if I were to guess, the pickup you're looking for is the Seymour Duncan Model '78. It is always the best pickup choice for full fledged rockin saturation. They can be had for a fair price any day of the week. Throw another bridge pickup in the neck, too if you want. There's no rules.

 

[ngjenkins]

Stock is always best. But if I were to guess, the pickup you're looking for is the Seymour Duncan Model '78. It is always the best pickup choice for full fledged rockin saturation. They can be had for a fair price any day of the week. Throw another bridge pickup in the neck, too if you want. There's no rules.

I'm VERY happy with the 498T in the bridge. The T Tops sounded like garbage when I originally got it but didn't realize it was actually the pots that were just making it a mess. Did the pickup swap and was so confused as to why they still sounded so anemic. Replaced the pots and suddenly the guitar came to life.

So I'm wondering if the T Top in the neck will be just fine now. The 498T is exactly what I'm looking for while I'm open to explore with the neck.

 

[dnabbet2]

From a technical point of view it is undoubtedly safer if the strings are not grounded ... provided that the rest of your equipment is in good order and properly grounded (any vintage amplifiers MUST be fitted with a properly wired 3 core mains cable) ...

I agree with you. Debate that I've seen has focused more specifically on how/whether single-coil players especially can work around the noise associated with an ungrounded instrument. Although your hand can make contact with the pickup height adjustment screws or jack or other necessarily-grounded parts ... contributors point out. But vintage gear was not always, and is not always even now, correctly configured. When I was still gigging, the house mains weren't always to code!