Thread: how about this: grounding produces noise

I was reading the other thread about grounding the lilliput vga connector to reduce the flickering. So as we know the vga connector attaches to the VGA port of the computer case, hence all around that area would be ground.

I checked the resistance between there and my car body (actually to one of the screws that bolts my seat to the car body) and found it to be around 4 KOhms. I thought, hrmm, that's too high.

So I ran a wire from the screw-bolt to the vga connector and attached it to the vga prot screw, and found the resistance to be about 3 ohms. (voltage difference between the screwbolt and the vga connector about 0.15V)

But now.. I get alternator noise! Which wasnt there before (maybe it was but I didnt notice it). It didnt fix the lilliput flickering either.

Possible problems?
1) That screw-bolt is not really car body
2) difference in potential between amplifier to CPU, or between preamp to CPU
3) quite lengthy ground wire (about 20 cm)
4) ground wire is quite narrow in diameter, about 1/3 the diameter of the power wire.

Hrmm, I could fix this problem by just removing the ground wire, but I dont want to hide the problem.. i wanna fix it for real