Grounded Too Well!? LOL

[spindlebox]

So this has happened to me a couple of times, and I have just done a jury rig to get me through, but I thought I'd start a discussion here.

I went ahead and used the Stew Mac grounding paint on the inside of my control cavity (and this has happened to me with copper tape as well).

Today, I was wiring up my jack, and it kept shorting out when I would insert it in its' hole in the body.  I finally discovered that when the tab from the TIP would touch the inside of my control cavity, it would ground out.  I taped the tab up and was able to insert it with no problems.  To fix it, I went ahead and got some paint and painted the inside of the control cavity around where the jack goes in, and the problem is solved.

Has anyone experienced this, and if so, what did you do about it.  Is there some sort of wiring configuration that causes this somehow?  I haven't done anything out of the ordinary ground wire-wise with this bid to my knowledge.

Thanks!

[henrim]

I’m not sure I understand what the question is, but since you used conductive paint there is likely ground connection on the paint layer. Through potentiometer cases or whatever grounded part is in touch with it. Obviously if your hot wire touches the paint, it will get shorted.

[curtisa]

4 hours ago, spindlebox said:

if so, what did you do about it.

Make more use of shielded wire. Yes, it's more of a fiddle to put together, but depending on the electronics you're using you have the potential to wire the entire thing without even reaching for the shielding paint or copper/foil.

If I were building a twin humbucker guitar I probably wouldn't bother with shielding and just use shielded wire instead. Or if building something like a Strat, use shielded wire in a more targeted fashion - the bullet jack cavity for example doesn't need it if you run a shielded wire from the jack to the volume pot. If the pickups come already fitted with shielded wire there's no reason to also shield the pickup cavities or the wiring channels from the pickup cavities to the control cavity.

...or just make your cavities bigger so that nothing has a chance to touch a grounded portion.

[spindlebox]

16 hours ago, henrim said:

I’m not sure I understand what the question is, but since you used conductive paint there is likely ground connection on the paint layer. Through potentiometer cases or whatever grounded part is in touch with it. Obviously if your hot wire touches the paint, it will get shorted.

The jack shorts out when it comes in contact with the inside of the control cavity (the hot tip).  When the sides of the jack touch the inside of the cavity.  I was just wondering if anyone here has experienced that.  It is a single coil bass, so I shielded it.  

[henrim]

11 minutes ago, spindlebox said:

The jack shorts out when it comes in contact with the inside of the control cavity (the hot tip).  When the sides of the jack touch the inside of the cavity.  I was just wondering if anyone here has experienced that.  It is a single coil bass, so I shielded it.  

Yes, I understood that. I thought that the risk of short was so obvious that I was not sure what you were actually asking. But like I said, potentiometers are the likely path for the conductive paint becoming ground. And it’s ok but you need to somehow insulate the jack from touching the ground.

[spindlebox]

7 hours ago, henrim said:

Yes, I understood that. I thought that the risk of short was so obvious that I was not sure what you were actually asking. But like I said, potentiometers are the likely path for the conductive paint becoming ground. And it’s ok but you need to somehow insulate the jack from touching the ground.

Nothing is obvious to people that are fairly new at things BTW.  This is why people ask questions.

I have never heard of anyone talk about having to insulate wires and components to prevent grounding out on the faraday cage.  

[henrim]

Yeah, well I’m sorry if I came across arrogant. What I meant with obvious is that if you connect the signal to ground, it gets shorted.

I guess it is not obvious that the conductive paint becomes a ground plane unless you insulate potentiometer cases from touching it. The jack, it either needs enough space around it or it needs some other form of insulation. In any case I would keep the signal path from touching the cavity shielding. 

[Bizman62]

9 hours ago, spindlebox said:

When the sides of the jack touch the inside of the cavity.  I was just wondering if anyone here has experienced that.

I've encountered that with my Strat. Everything worked well as long as the boat was unattached but when the screws were tightened the tip or rather the tip connector of the jack hit the copper tape and no sound. Finding the reason took quite some time! Finally I simply took a chisel and removed some wood from inside the jack cavity.