Still getting a hum with hum-cancelling pickups - grounding issue?

[Patriot54]

I have a friend wiring my Strat, but his specialty is wiring speakers not guitars. It seems to be 99% done but I still get a pretty loud hum/static which stops completely when I touch the metal knobs or other metal parts. It has a humbucker and 2 hum-cancelling DiMarzios. I've read that this could be due to the wires to the jack being reversed. Also, the bridge and middle pickups are far away from the strings - could that be allowing interference into the signal? I can take pictures if necessary.

:help:

 

[greywolf]

it sounds as though it is either not properly grounded , or mis wired

 

[Patriot54]

Here's a picture - maybe someone will notice the problem.

By the way, this is only a 3-way switch. There's a humbucker at the bridge, and hum-cancelling Strat pickups at middle and neck. One master volume and one master tone.

Maybe grounding to the bridge would correct this problem.  :dontknow:

 

[drewfx]

Bridge needs to be grounded.

 

[Cagey]

Yeah, I don't see a bridge ground, either. I do see one helluva lotta unshielded wire, and some questionable solder joints.

 

[Patriot54]

Yeah, I don't see a bridge ground, either. I do see one helluva lotta unshielded wire, and some questionable solder joints.

Thanks for the advice everyone.

I had forgot to tell my friend about grounding to the back of the bridge because I had everything assembled before we started the wiring. I am clueless about electronics but he worked at Bose wiring speakers so we're trying to figure out guitar wiring by trial and error.

I don't see much unshielded wire except for the ends of the blue wire. Also, how would you do the solder better based on this picture?

 

[reluctant-builder]

The wire is insulated, but not shielded. Shielding inhibits interference, insulation just protects the wire from coming into contact with other metallic parts and grounding out at unwanted points.

 

[Patriot54]

The wire is insulated, but not shielded. Shielding inhibits interference, insulation just protects the wire from coming into contact with other metallic parts and grounding out at unwanted points.

I thought shielding wasn't necessary with hum-cancelling pickups? Also I used good quality wire to replace some of the thin wire when possible.

 

[Cagey]

Humbuckers normally come with shielded wire leads, but the rest of the control cavity is up to you. The humbucker, by its design, will cancel out any hum it picks up, but that doesn't help you outside the pickup.

You don't need much gauge-wise as far as wire is concerned. But, it does have to be shielded or it'll pick up electrical noise from the surrounding environment, which is pretty much any civilized/inhabited areas on Earth.

All that blue, green, and red wire is unshielded, so it's acting like antennae for RFI/EMI. The solder joints I'm wondering about are the ones going to the pot housings. Looks like the housing never got hot enough to flow the solder, so it's possible those are cold (high-resistance or open) joints.