Model A1286. Released February 2011 / 2.0, 2.2, or 2.3 GHz Quad-core Intel Core i7 Processor

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Backlight not turning on after water damage. What to do?

Hi all, first time poster long time follower. I have a slightly water damaged MacBook Pro 15" early 2011 A1286 that was given to me. I was told it was caused by a bit of melting ice, the water got inside the casing where the DC-in board is located.

By opening it, I could see there was corrosion mainly on the DC-in board and a little around the the chips on the logic board on top where the USB ports are located.

Here's the thing, EVERYTHING works, it boots, sound works, ports work it charges when connected. However, the display does not light up. I can see what is on the screen under a source of light, the same as if when the brightness is turned down (obviously, I tried adjusting the brightness with F1, F2, without success). It does work perfectly fine connected to an external display.

I have since then cleaned the corroded areas with alcohol and it didn't change anything.

I have also noticed that there was what appear to be a small burn mark on one side of the display connector (on the metal part) and 2 of the pins on the cable are silver-ish instead of gold-ish.

I really don't know what to do to fix this baby up. Any thoughts/suggestions would be greatly appreciated. :)

PS: just for your information, I'd say i'm somewhat experienced in mac repairs, having repaired countless parts/devices. But never really ventured into soldering anything though, yet! I'm a bit worried it might come to this.

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First try hooking it up to an external monitor to see if the logic board is generating a video signal. Examine the LVDS cable and socket for corrosion then reseat it. Here's our guide on attempting water damage repair, try this for cleaning the corrosion off: Electronics Water Damage

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Pins 38, 39, and 40 on LCD connector sound fouled up. What you need to do is see if there is a short to ground on those pins. Put multimeter into diode mode, red probe on ground, and black probe on pin 38, 39, or 40 of LCD connector. Put reading here.

Then remove LCD cable, and do the same thing, and put the reading here.

This will give us an idea if the short to ground on the backlight rail is in the LCD cable/LCD, the board, or if it is not there at all.

You should see 0.519-0.546 in diode mode on a working LP8550 backlight circuit. 0.258 if the WLED driver is bad, and 0.000-0.027 if there is a short inside the board, LCD cable, or LCD.

Also, backlight fuse. Find schematic and replace that if there is no short and go from there.

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