How to tell screen wire polarity?

**grandimperial** · 04-27-2008, 07:58 AM

Hi,

I bought a second hand screen off a memeber off this forum and he included the in car power wire with the "egg" chopped off, however i dont know which wire is positive and which is negative/ground?

I think the screen is a lilliput 619gl but there was no casign or box to confirm this.
One wire has a white stripe down it and the other is solid black.

I have checked on the controller board to see if it says if the pin or the outside is positive or negative but it does not say?

I have a multimeter and i can check which wire on the cable relates to the inside or outside of my barrel connector but how do i tell what the polarity is on the controller board?

**Rob Withey** · 04-27-2008, 08:07 AM

The power ground is likely to be the same ground as the video ground on the VGA plug. A multimeter will tell you that.

**hailrazer** · 04-27-2008, 08:10 AM

Plug in the power adapter. Turn your multimeter to the Volts setting. Touch each wire with the mutimeter leads. If it says -12v the leads are reversed and change them . When it says +12v look at the leads. The black lead will be ground (negative) and the red lead will be positive.

Then look on the power adapter. It will say if it is a positive tip or negative tip power supply. Positive tip (-)------( O----(+) negative tip (+)-------(O------(-)

Then on the connector on the board hook it up the proper way negative or positive to the center of the adapter plugs center pin.

**grandimperial** · 04-27-2008, 08:54 AM

Sorry im really confused by that,

What i have is basically two wires chopped off on one end and a barrel connector on the other.

So i cant plug my lead into a power supply.

One wire is a white stripe on it and th eother is solid black.

Would you mind explaining it agian to me,sorry and thanks?