Monitor Distortion Problem

**spoonraker** · 10-02-2007, 05:38 PM

I've been fighting this problem off and on for quite a while and have never really gotten a real grip on what exactly is causing it.

I get interference in my monitor. Just recently it got really bad. (I didn't change anything, it was pretty random) If the music is off there is a slight amount of movement on the screen, but once the music turns on it gets much worse. The screen will distort, get fuzzy, and if the volume is up even go completely black for a while.

It is powered by my cigarette lighter and the VGA cable is 15' long and runs into the trunk into the back of the PC. The VGA cable does not ever cross a power wire, at the closest point it runs maybe 6-8'' away from one. There is a bit of slack (maybe 3/4 feet) in the trunk that I simply have kind of pushed aside into the corner of the trunk. (there are no power wires here, RCAs yes, but nothing that would put out interference)

Any ideas?

**dprothero** · 10-02-2007, 05:56 PM

You have to isolate the problem. Can you plug a laptop directly into the screen with a shorter cable? See if the problem persists. If the problem goes away, it's the 15' VGA cable (some kind of interference -- or just a poor cable). The problem remains, then it's interference on the monitor itself, perhaps from the power source. Can you try plugging it into the regulated power of your power supply?

Have a buddy with another screen you could try?

Anyway, you get the idea. Keep trying swapping out individual pieces of the setup (only one piece at a time) until the problem goes away... then you've isolated the culprit and can proceed with correcting the problem from there (post another thread if need-be once you've isolated it).

**BiG K** · 10-02-2007, 06:04 PM

use a ferrite core at both ends and see if that helps. Also with a bit of foil, wrap the part of VGA cable near a power wire.

**spoonraker** · 10-02-2007, 06:05 PM

I have a laptop I can test and about a billion extra VGA cables of different lengths. (what kind of computer programmer doesn't have a bunch of torn up computers and stuff laying around? lol) It would be a bit of work but I'm sure I can find a different power supply for it as well. I'll also take it inside and test it away from the car to make sure it works in general.

I'm still at work I just thought I'd throw up a post to see if anybody had any great ideas or things to try other than general noise troubleshooting techniques.

**spoonraker** · 10-02-2007, 07:23 PM

Well I didn't have to do much to eliminate the cable its self or it's proximity to the power cables as a problem.

I plugged the laptop in...absolutely no noise. Switch to CarPC, noise. Even with the sound system running full tilt from both the laptop and the CarPC, the laptop never had noise and the carPC always did.

I have yet to take the CarPC inside and test it on the different monitor/cable though.

**dprothero** · 10-02-2007, 09:37 PM

Yes, that's the next step, but I'm guessing the CarPC will be fine inside. Are you using onboard VGA? Maybe try another VGA card, if possible? What kind of case is your computer in? Perhaps it needs better shielding.

**spoonraker** · 10-03-2007, 10:00 AM

Yeah I'm using the onboard VGA.

My case is 3/4'' MDF, pretty basic carpeted box

This is it without the lid on. It's fully enclosed and mounted in the corner of the trunk behind the tail light.

**HiJackZX1** · 10-24-2007, 02:55 PM

You know what, I have the same issue..... Does your car use amps? My setup had the amps (micro amps) and the pc near each other, I have major distortions where the screen pulsates and if the bass is loud, it goes black and you have to wait till the song stops to see the screen again. What I decided to do is rewire the car, only the amps are in the back, the main power cable is run under the car (to avoid the cars original cables, I hear the engine noise in the speakers), and I will use only the factory ground points (I think the ground points I am using now arent getting good ground). Also do not have the signal cable for the amp near anything, that can cause distortions too. Also having to much monitor cable can cause issues too.... Im going to be getting a shorter VGA wire and maybe putting the the magnet cylinder thing on the end..... Also, with the distortions..... is your video slow?

Hope this helps in some way.

PS: I also have the same board as you, maybe our boards are extra sensative to surrounding noise cause by electrical wiring.

**spoonraker** · 10-24-2007, 03:16 PM

Actually it turned out to be a bad ground. I couldn't notice it just by looking but when I accidentally got the ground wire caught on something it popped right out.

I redid the ground in roughly the same spot with multiple screws and locking washers and all the interference went completely away.