'76 Starfire 4 grounding problem?? (major hum)

[waveland]

Hey All,
Sealed the deal on the '76 SF-4 that GAD once owned. The guitar is BEAUTIFUL!! Just opened up the shipping box tonight, plugged it in and MAJOR hum. Twirled all the knobs, messed with the jack. Hum stops when I touch the toggle switch and the jack plug at the same time, which doesn't leave me many fingers left to play guitar! I'm thinking something jarred loose in the shipping process and because it's getting late I thought I'd start dealing with it tomorrow I'm guessing with the jack? Any ideas that you have would be most appreciated!
Thanks,
Dave

photo courtesy of GAD

 

[GAD]

Hey man congrats! I'm glad it's back in the TLG fold. It's beautiful isn't it?

I can tell you that it didn't hum like that when I had it.

I wonder if the last guy tried to rewire it for stereo then crossed the wires when he put it back?

 

[Default]

Sounds like a ground wire isn't connected, if the hum goes away when you touch it. I'd check the jack too.

 

[waveland]

Hey all,

Took the guitar to my luthier today and learned some good stuff. The gray wires from all the pots, toggle switch, master volume are kind of like a tv cable. There is an insulated solid wire in the middle and around it is an insulated strand wire. The existing wire job was only using the solid wire to the positive (tip end of the jack) and an existing ground wire to the ground. What he did was to use the solid wire for the positive and then he used the strand wire (as well as the existing ground wire) for the ground. The result is an SF-4 that (when not being played) is quiet as a church mouse!
Hope that all makes sense, thanks for the suggestions and all I know is this baby plays like butter!!

Dave

 

[GAD]

Congrats man! That guitar is as dead-sexy as they come. If it had a wider neck it would still be mine.

The finish/wood/look/feel of the guitar always reminded me of a fine antique violin. Enjoy it!

 

[Default]

The braided shield should always be connected to the ground lug on the jack. It does sound like the interim owner messed with the wiring, trying to get stereo working, I guess.
Enjoy that beauty!

 

[capnjuan]

The braided shield should always be connected to the ground lug on the jack. It does sound like the interim owner messed with the wiring, trying to get stereo working, I guess. Enjoy that beauty!

... Or ... he had undefined humski of his own and went with coax thinking the built-in shielding would help ...

 

[Default]

Yupper! Pics of the wiring would be clearifyin'

 

[capnjuan]

Si.