Grounding

[JohnnyO]

Put a new Sony head unit in the Jeep today. Got a wiring adapter and everything, but you still need to ground the unit separately from the adapter. I used a dash screw that seems to be in the same neighborhood where the factory ground is attached, although there was a bit of oxidation on the metal. Everything works, however on weaker radio stations I notice some static with the engine running that isn't there when the key is on ACC. It's not bad, but I hear it. Sand the metal? Bolt the prongs of the two ground wires together? Figure a way to attach a 20g copper wire to a fat flat piece of aluminum wire? Something else that isn't the ground?

Thanks.

 

[bobcat481]

I had the same problem with a c.b. a few years ago. The power wire was picking up "static" from the engine electronics and spark plug wires. You would hear the "static" rev up and down with the engine rpms. My brother-in-law gave me a filter (he called it a choke) and I installed it in series with the incoming power and the noise was eliminated. The filter looked like a coil of wire wrapped around an iron core. Radio Shack sells them for $10 or so. It might be worth a shot, but I promise nothing.

 

[JPNinPA]

Yes power and ground lines are how the noise is entering. We really don't know the additional ground is the cause but we can assume you have a grounding loop.
1.) You could use the same ground point.
2.) Ensure the dash screw you used is actually connected to the frame (ground plane) and clean the oxidation and remove any paint to reduce resistances.
3.) Connect the head unit ground to the case of the unit
4.) Above choke will work. There are ones for the power line and others in the ground line.

 

[bobcat481]

4.) Above choke will work. There are ones for the power line and others in the ground line.

What is the difference in the one for the power line vs. the one for the ground line? Just curious as to which one I have, and if I used it right. I just assumed mine was supposed to be on the power side.

 

[JPNinPA]

What is the difference in the one for the power line vs. the one for the ground line? Just curious as to which one I have, and if I used it right. I just assumed mine was supposed to be on the power side.

The power line ones cab be a low pass filter. These take RF noise out thru the use of capacitor network. The ground like noise filters can be a transformer that decouples the signal "Noise" from the ground.
Another way of answering this is some noise sources send the noise thru one of the lines. Take alternator noise. Many times the alternator noise comes in on the ground line. In this case power line filters will not work.

Hope this helps. Sorry for the delayed response Took the boy to scout camp.:MDB2:
€(=-)<

 

[bobcat481]

Ok...I see the difference. Your boy in Scouts?......and are you a pack leader? I would like to get my boy involved (5), and think it would be awesome to teach young ones the "finer things in life". All the good things like camping, trapping, firemaking, ect. All the things a good boy likes with the exception of Skoal spittin' that is.

 

[JPNinPA]

PM'd ya