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lcd backlight? Answered

i have two broken lcd screen and salvaged only the backlight panel, power supply, and sreen display circuitry
i it to light up all the time and not only 2 secs after you light it up without pluging any computer in the video ports.
HOW?
Thanks to all of you:)

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jeff-o

Best Answer 7 years ago

You'll have to fool it into thinking it's plugged into a computer port. Somewhere on the backlight driver board there is probably a control signal that commands the light on and off. Find it, and override it by connecting the signal directly to ground or +3.3V/+5V.

Just be careful when you're probing around, the backlight driver runs at a few hundred volts! Don't get zapped!

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jeff-o

7 years ago

OK, you tried; but what did you try? What did you discover so far? Perhaps you just didn't find the right signal or signals.

i went on the dvi connector and tried all the connections one by one with a +5v power supply(for that i simply used an atx power supply) and it didn't work so i went on the vga connector and did the same thing.didn't work .but now that i think of it , would it not be easyer to short circuit all the transistors on the HV power supply one by one and see what happens?because on the vga connnector i'm almost shure it lights on because the blue red and green signals are telling him to.

Oh, it's not that simple! There is no "Backlight On" pin on either of the connectors!

No, the signal you're looking for will be on the monitor PCB itself somewhere. Probably somewhere in between the chip with the largest number of pins and the backlight driver. It would probably help to see if you can check the IC part numbers online to find a datasheet.

I can almost guarantee that simply shorting the transistors will do nothing, and indeed may cause more harm than good. So don't do it.

ok i'll try to see the the ic part number online as soon as i get back from my 3 day vacations from the countryside
thx again