JP6 bridge and cavity shielding not connected to ground

[valentin]

Hi,

With my new JP6, I have loud buzzing that stops immediately when I touch the strings and the jack at the same time. Obviously, the bridge is not connected to the ground. I used a multimeter to verify that there is indeed no electrical connection between the bridge and the output jack.

So I opened the cover of the pot cavity to see if there is some loose cable or so. I found that the bridge is wired to the cavity cover, and the “hull” of the volume potentiometer. I checked that all those connections are still well conducting using the multimeter. There is also electrical connection to the metal bottom plate of the cavity.

There is, however, no connection between these and the ground lug of the output jack of the guitar! Wonder if that is “by special design” or a fault? In my other electrical guitars, the bridge is always connected to the ground.

I could send the guitar back to the dealer and ask him to get the problem fixed, but that would take some as I bought it abroad. So I am tempted to solder in a resistor connecting the ground lug with the bridge’s wiring.

Would there any negative side effects? How would warranty be affected by such autonomous repair actions?

Maybe anyone had similar problems and can share some experience? Thanks a lot!

Valentin

 

[beej]

Stock JP6 with no piezo?

There should be a connection from the back of the volume pot to a central point in the cavity (on the wall, adjacent to the trem cavity), to which the bridge, output jack, and cavity cover are all connected.

Can you post a pic of the cavity?

 

[valentin]

Yes, it is a JP6 without piezo, and it should be stock. There is the central point you mentioned that connects the back of the volume pot, the bridge, and the cover, but not the jack :-( I attached a picture, hope you can see it well enough.

 

[beej]

Looks like someone has been in there before. Seems to be missing an extra ground connection between the output jack and the central ground terminal. Should be a quick fix if you have a soldering iron handy.

 

[valentin]

Thanks, I'll try that. Just out of curiosity, can you spot some other modifications in above picture? I wonder why someone would open the guitar just to remove a ground wire

Valentin

 

[beej]

I can't say for sure, since I haven't been inside too many JP6s. On most MM guitars, the wires to the output jack are braided.

You're missing ground wire (again, hard to tell from the pic, but you're not seeing continuity). I can just barely see the wire from the tone pot to the volume, but you'd know if the tone control didn't work.

Who knows. Maybe somebody replaced the output jack, had different pickups in there, etc. If it plays well and sounds right, then it's all good