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laptop backlight inverter pinout ?

Last response: in Laptop Tech Support
May 1, 2014 9:41:25 AM

Hi, it's my first post in this forum, although I often found solutions here googling.

I I am going solar and need a low energy monitor. I plan to reuse some LCD screen from broken laptops, as they are low consumption.
I will buy, or find some VGA controller board, in order to use them as monitor, but I first need to test their backlight/inverter.
The 2 inverters I looked at (from acer aspire 3100 and 5100) have 7 pins at their connector to mobo.
I found:
- 2 pins to ground
- 2 pins to Vin (12V I guess, OK for me)
- 1 pin for enable
- 1 pin for dimm adjust
- 1 pin more is connected on the board, but I am not able to recognize it (no schematic found). What is it for (input, output?), and what should I do with it ?

Thanks so much.
a b D Laptop
a b C Monitor
May 1, 2014 9:51:11 AM

I too am implementing a solar-based system for running a PC. I've not converted a monitor yet, but I plan to use a LED-backlit monitor that uses a power brick. Instead of the brick, I will use an auto adapter (e.g. a laptop adapter) that outputs the required voltage. If necessary, the wires can be cut and switched if the polarity is wrong. A LED monitor will use a lot less power than a fluorescent-backlit monitor.
May 2, 2014 12:26:12 AM

You are totally right, Leds are (quite) more efficient.
My goal was to reuse scratch as much as posible (doesn't need more energy and prime materials + will not add to dumps).
I did'nt find led monitors, but laptops ccfl displays (although not so bright) are usually lower consumption than desktop monitors: I hope to save 10W from the 20W my actual monitor uses.
I am still with the inverter pinout problem.
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a c 243 D Laptop
a b C Monitor
May 2, 2014 7:14:51 AM

Hi, can you trace the wire to the connector on the motherboard of the laptop, and which pin corresponds this wire on the 40-pin connector.
May 3, 2014 11:09:32 AM

Thanks for your help: displays , inverters are from scrapped laptops, and lots of parts are lacking, I don't even know which mobo belongs to which display :-P.
Finally, I did some more reverse engineering, finding out that the unknown pin was input, and could probably accept voltages from ground to Vcc.
Tests showed that this pin has to be connected (ground is OK, but Vcc works also).
Not connected is backlight off.
I could test inverter+backlight, and display came all white as it has to, so this problem is solved.
Next step will be to find a usable vga controller for this display (AUO B154EW04)
May 9, 2014 1:48:01 PM

You can convert the LCD to led backlighting and dump the inverter. This will drop power consumption on a 17" screen by about half (CCFL backlight is about 20W, LED is closer to 5W, LCD circuitry is 5W)

I've just done this on a set of monitors and am in the process of converting a laptop. In my case it's about the brightness (CCFLs fade out over time, leds don't) but the added life is a bonus given that the complete solution is only about $5/monitor more than a replacement CCFL. The led backlights are at least twice as bright as the CCFLs they replaced (sunlight viewable, which the CCFLs never were)

If you take this route, remember the CCFL contains mercury and should be disposed of thoughtfully.

Laptop LCD panels tend to use about the same amount of power as standalone monitors. The difference lies in the backlighting. The monitors all had four CCFLs, which were replaced by 2 led strips (top and bottom), whilst laptops tend to only have one CCFL

Bigger/older screens will get better power savings. Older inverters are less efficient - and watch out, they BITE if you're not careful. There's 1500-3000V at the nasty end of the board.