Weird ground problem on Epiphone Thunderbird

[Kerry Brown]

Got my Thunderbird back from the grandkids and took it to last night’s practice. I had noticed some hum that sounded like a bad ground but it wasn’t that bad. The jam space has fluorescent lights. The hum was super loud in the jam space. It went away when I fiddled with the input jack. This morning I popped the back cover and saw it was a design flaw. The route is too shallow. When the guitar cable is plugged in the tip makes contact with the back of the cover which has factory installed shielding tape on it. I glued some thin cardboard and put electrical tape over the cardboard where the tip was making contact. Problem solved.

 

[chilipeppermaniac]

The body is too thin? Kerry

I had no idea a bird body was thinner than an SG.

 

[smitty_p]

Got my Thunderbird back from the grandkids and took it to last night’s practice. I had noticed some hum that sounded like a bad ground but it wasn’t that bad. The jam space has fluorescent lights. The hum was super loud in the jam space. It went away when I fiddled with the input jack. This morning I popped the back cover and saw it was a design flaw. The route is too shallow. When the guitar cable is plugged in the tip makes contact with the back of the cover which has factory installed shielding tape on it. I glued some thin cardboard and put electrical tape over the cardboard where the tip was making contact. Problem solved.

Good troubleshooting.

Just curious, can you adjust the nuts on the jack (or even remove the inner nut) so that it sits further from the cover plate?

 

[Kerry Brown]

There was no inner nut or washer. That was my first thought as well.

 

[Kerry Brown]

The body is too thin? Kerry

I had no idea a bird body was thinner than an SG.

It is quite thin but there is room to make the route a bit deeper. It would only need about a quarter inch.

 

[Kerry Brown]

Ground hum seems to be a common problem on TBirds. Usually the pickups get blamed.

 

[Thatbastarddon]

It is quite thin but there is room to make the route a bit deeper. It would only need about a quarter inch.

I’d avoid thinning the top. I’d drill the cover before thinning the wood down.
just my opinion.

 

[Kerry Brown]

I’d avoid thinning the top. I’d drill the cover before thinning the wood down.
just my opinion.

I won’t be doing any routing

The route could be deeper. The jack barely fits through even with no washer or nut on the inside.

 

[Inspector #20]

@Kerry Brown - I had this problem on a 2016 Gibson SG. I raised the input jack with a stack of washers (the correct washers collected from my parts bins) then add an 'X' of black electrical tape to negate proximity interference. It's actually a common problem on a lot of guitars....

If there isn't enough thread protrusion, you could spot-face the input jack area from the back with a Forstner bit in a drill press:

Amana Tool Forstner Bit for Output Jacks - StewMac

Forstner bits for removing wood from cavities and drill jacks

www.stewmac.com

 

[Inspector #20]

Ground hum seems to be a common problem on TBirds. Usually the pickups get blamed.

And for good reason. many have P-90's...and a complete lack of shielding.

 

[Kerry Brown]

@Kerry Brown - I had this problem on a 2016 Gibson SG. I raised the input jack with a stack of washers (the correct washers collected from my parts bins) then add an 'X' of black electrical tape to negate proximity interference. It's actually a common problem on a lot of guitars....

If there isn't enough thread protrusion, you could spot-face the input jack area from the back with a Forstner bit in a drill press:

Amana Tool Forstner Bit for Output Jacks - StewMac

Forstner bits for removing wood from cavities and drill jacks

www.stewmac.com

If the cardboard and tape doesn’t fix the problem I’ll try this. A 1/4” deeper combined with some form of insulation to stop the tip from touching should do it.