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No backlight on MacBook Pro 820-5482-a

Hi, I usually repair iphone logicboards and have no problems with replacing most ic's and trouble shooting, but when it comes to macs im a bit of a noob. Half the problem seems to be actually finding a boardview and schemetic for this board otherwise I would have a fair idea where to check etc on it.

So the customer somehow managed to bend the hinges back on the screen and damaged it. I bought in a new screen unit for it and I now get a screen on it, but there is no backlight and the apple logo is not lit up.

Usually I would just go to the likes of zxwtool or my schematics for that board if it was an iphone and check voltages etc, but I see on the mac schematics they dont actually include a board layout on them, and I cant find any either, so does anyone know what the voltages are for this circuit, where I need to be checking them, or components to test etc ?. I have found what I think is probably the backlight fuse, and it appears to be ok. So im guessing its possibly the backlight driver or the lcd driver ic, but a google search for ic numbers brings up things like regulators, power supplies etc, but it doesnt say what for, e.g backlight circuit.

I have inspected the lvds connector under microscope and it seems to be fine, so im guessing the act of snapping the screen off has killed something in the backlight circuit.

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crea 820-5482-a is the Input/Output (I/O) board for the MacBook Pro 15-inch retina released in mid 2015. It includes the SDXC slot, HDMI, and one USB slot but not the backlight so I am a bit confused by that. the backlight circuitry should be on your logic board. your board should be a 820-00163-A

Post some good images of your complete board with your question. Use this guide Adding images to an existing question for that. It might help us to help you further.

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Deck the Halls
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Firstly find and Google the board number for the schematic and board view. The board number will be on the bottom left of this board usually, and will either be 820-00138 or 820-00163. If it is 820-00138, last time I checked, the board view files are not available. I have used the board view file for 820-3787 in the past, since it is very similar to 820-00138.

With the screen plugged in, measure pin 1 on the LCD connector and let us know the reading (bottom pin, but not the spaced ground pin). If you are getting nothing, or 0. something, check for a short to ground on this line.

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Thanks, it's the 00138 board, have checked and no short to ground on that pin, is ol.

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10.89 ohms on that pin to ground using a fluke 15b

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This is the first pin after the ground pin going left to right.

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Have just checked it out using the flir camera and nothing unusually hot that I can see.

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What is the voltage for this pin?

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