Screen "ground loop" / regulated power

**MCiN7** · 09-08-2011, 07:37 PM

Hi all,

Thought I'd try get some advice on the best way to fix the noise issue I'm having.

Problem:
Horizontal lines throughout the screen on all (direct battery / M4-atx / accessories) power sources. (Haven't tried a power source that isn't apart of the car, what's the point if I know the problem is within the car.)

Solution so far:
The 5V rail works sometimes, perfectly with no noise on the screen.
I say "sometimes" because most of the time due to it only being a 5v rail, the screen flickers (turns on and off).

Is there a way I can get 10v from the 5v rail? Diodes, soldering?

Or any other things you would like me to try?

I have a 40a noise suppressor but that does nothing.
I have also used other suppressors that go directly onto the alternator, nothing.

There is no noise coming from my amped speakers.
But the lines do change with RPM.

Edit:
0AWG power wire running to distribution block with 4x 4AWG outputs

Computer;
Pentium E6300 or E5500, don't have the exact model, never took notice and as it's doing everything fine
2x 512MB DDR2 667 RAM
160GB 7200RPM Sata Hard Disk Drive
M4-ATX Power Supply
Asus Xonar D1 Soundcard

Screen;
Response "QM3744" 7" Touch Screen LCD Monitor

Amp(s);
1x Response "AA0426" it's their old 100WRMS x 4 channel amp series.
I also have 1x Response "AA0453" but was getting feedback due to the digital power supply, so it's been sent away under warranty to try and get fixed, if not I get to score another "AA0426".

**DodgeCharger** · 09-19-2011, 11:16 AM

Do you have a good quality VGA? I had to go through 3 cables until I bought a monster cable and it fixed my noise issue. Also be sure Video and Power cables are away from each other. Just a thought. Good luck.

**meryan00** · 09-19-2011, 11:22 AM

I do not understand why you think there is no point to testing a outside power source, that would help rule out that part of the problem is the monitor itself, and perhaps being in car just makes the issue worse.

I would test it outside with the video still coming from inside the car to see if there are lines, and again with a video source outside the car, if it has issues with everything outside the car then it is most likely the monitor. However if it has issues with the computer inside the car and none when the computer is outside the car then it is a computer/video cable issue. If it has no problems outside the car then it is like you thought and the power issue inside the car.

I just always try to rule out any other options

**DarquePervert** · 09-19-2011, 06:34 PM

Originally Posted by MCiN7

But the lines do change with RPM.

That right there tells me that there is a ground loop affecting your video signal.
Find a better ground for your screen and/or your video device (PC, DVD player, etc.).