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Topic: Hum issue on Gibson Century V2 (1952) |
Nils Kirschlager
From:
Germany
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Posted 16 Jun 2018 1:37 am |
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Hi guys,
I have an old Gibson Century (the blue one) with the original P90 in it. Only problem is the noise. It hums even when I run it clean into a Fender amp. Most likely a grounding issue, since when you touch one of the pots or the output jack, the noise is gone. There seems to be no ground wire connected to the bridge - is that normal?
Any advice how to solve the issue? I can provide pictures if needed.
Thanks in advance!
Nils |
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Jack Hanson
From:
San Luis Valley, USA
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Posted 16 Jun 2018 5:09 am
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| All of my blue Centurys have a ground wire wedged under the bridge and are as quiet as one could expect from an instrument equipped with a single-coil pickup. Look for an existing small hole drilled through the body at an angle from beneath the bridge into the pickup cavity. If there is no hole present, it's easy to drill one. Installing a ground wire from a good ground point such as the output jack or a pot casing to underneath the bridge will likely solve your problem. |
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Don Barnhardt
From:
North Carolina, USA
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Posted 16 Jun 2018 7:52 pm
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| I'm not familiar with your instrument but I had that problem with the lap steels I've been building. It drove me nuts until I changed the ground on my bridges. I dismissed the bridge ground because I had o zero ohms reading between bridge and ground. I ran anew ground wire the whole length of the bridge and the hum disappeared. I replaced the ground wires on my other instruments and lost the hum on them too. |
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Nils Kirschlager
From:
Germany
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Posted 17 Jun 2018 5:14 am
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Thanks a lot for your replies!
Jacks comment made me disassemble the bridge, and this is what i´ve found:
Someone obviously removed the ground wire for a refin and didn't solder a new one in place. The pots and caps in the cavity on the back seem to be all original though. Before I take everything apart, can anyone tell me where the missing ground wire was originally attached to? Jack, you mentioned it leads to the PU-cavity?
Thanks for your help! |
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Nils Kirschlager
From:
Germany
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Posted 17 Jun 2018 5:56 am
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Ok, i think i´ve found the spot. I've discovered another metal loop that was soldered to one of the shielded wires on one end and just touched another (red circle). Is this meant to be a base for another groundwire and has never been used or is there another purpose?
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Jack Hanson
From:
San Luis Valley, USA
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Posted 17 Jun 2018 7:51 am
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Not sure of the purpose of that ring lug; I don't think any of my Gibsons are similarly equipped. It may be a post-factory modification.
There is undoubtedly an existing hole drilled from the pickup cavity lengthwise through the body to the butt for the leads to connect to the output jack. The hole under the bridge should intersect it at approximately a 90 degree angle.
If it was my instrument, I would unscrew the jack plate from the butt, remove the jack from the plastic plate to prevent it from melting, and solder a jumper wire to the ground terminal on the jack that is long enough to thread through the holes to reach beneath the bridge.
Reassemble the instrument and any hum from its grounding issues should be gone forever. |
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Mark Roeder
From:
Milwaukee, Wisconsin, USA
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Posted 19 Jun 2018 12:13 pm
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Looks like the ground came off the shielding, you can see about 1/8 still there. Must have benn snipped off
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