Printer Friendly Forum Posts - wavy lines on lcd bad power supply?

Hi y'all! I need some electronics advice for my in-dash LCD install of a TM-868 8" touchscreen VGA monitor.

First of all, the LCD works great, good video and touchscreen ability. But I can easily notice wavy lines slowly scrolling across the screen over and above the image on the monitor.

I've narrowed it down (I think) to the power supply... originally, I was powering it off the +12v rail of my PC's power supply (ATX 300w power supply using a 700w inverter). Then I moved over to a 160w M2-ATX and again used the +12v rail, but still have wavy lines. I tried using a DC-DC regulator with 12v output (and about 1.5a, more than enough for the TM-868 LCD), but again I still have wavy lines.

Originally, the TM-868 comes with a 12v AC-DC wall adapter, and it is rated at 1 amp. When I use this wall adapter in the car with the inverter, the LCD is fine, no wavy lines.

What does this mean? I dabble a little in electronics and can read basic schematics, and I usually see a capacitor or something bridging the +Pos and -Gnd lines, I'm guessing this is able to "clean" the power and make it more stable.

How can I modify my DC-DC supply so that I don't have wavy lines on the LCD? Using an inverter works for now, but is far from ideal or efficient, plus then I have to manually plug in the LCD when I want to use the CarPC. Can anyone advise on adding a capacitor of some kind to fix this?

Again, I don't know enough to start experimenting myself, but if someone can provide some guidance, I have the tools and parts to make it work (I think!)...

Thanks,

Warren