Is this a ground loop i'm seeing in my LCD?

**iamgnat** · 05-09-2006, 09:58 PM

I got my system hooked up and working tonight. I had to take a quick trip while my LCD wasn't working and did not noice the tell-tale buzz/whine of a ground loop in my speakers with no music playing, but once I got the LCD working again i'm noticing lines that I haven't seen before (in the house). They look almost like scan lines.

Do I have a ground loop? If so, how do I best go about fixing it for an LCD (or is it just the same stuff as for audio)?

Thanks,
-dave

**xmadcowx** · 05-16-2006, 07:41 AM

Having the same issue. Anyone?

**maxxell** · 05-16-2006, 04:40 PM

It's very possible it's a ground loop problem. Another possible cause is interference with the VGA signal somewhere between carputer and screen (I am pretty sure VGA is subject to interference from power wires).

What kind of screen do you have? Lilli? Xenarc?

**iamgnat** · 05-16-2006, 10:45 PM

Originally Posted by maxxell

I am pretty sure VGA is subject to interference from power wires

This could be my issue. My cable is running in a bundle that has both the power for the LCD as well as the ignition wire running to my power supply.

I'm guessing that my only answer is to pick up some better insulated wire for my power and ground wires?

Thanks,
-dave

**Gibson99** · 05-20-2006, 02:55 PM

not necessarily... since your ign lead and lcd power wires are pretty small, you can route them somewhere else. ie: away from each other and away from the video cable. try to keep your vga cable away from the vehicle harness too.

**wrk king** · 05-22-2006, 10:06 AM

The easiest way to get rid of interference is by using 4 meathods.

1. Ensure you are running power to the carputer DIRECTLY from the battery using the shortest distance possible.

2. Ensure that the gound that you are using for the carputer and the screen are of the shortest distance possible and directly to the vehicle body/frame.

3. Use clip on ferrite beads on the video and power cables for both the carputer and the screen

4. A last resort is to place ferrite beads on the vehicle ECM to eliminate RFI.

What you are seeing on your screen is injected RFI coming from the car. There are 3 points of interest in a vehicle that can produce this type of interference. By using the 4 steps above, you can easily eliminate all RFI/EMI from within a vehicle.

I have a very good article on this using RF radio equipment in a vehicle and it can be found at http://www.ka1zfe.com/portal/forum/f...sp?TID=42&PN=1

I run a very high power HF Radio station in my vehicle as well as a carputer and I use a wireless screen. I was using a hard wired screen, but eventually went to a wireless screen which takes care of all of the problems of RFI or DC grounding injection.

I have this wireless screen for sale at Panasonic Toughbook Wireless touchscreen display

Here is a picture of the lengths that I go through to ensure I do not have any issues with both power and grounding:

Good luck!
Adam