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Macbook Pro A1150 very dark screen

edited June 2012 in MacBook Pro
Found a Macbook Pro on CL for $100. The screen is very dark. Read many threads, I purchased a inverter board off ebay. Swapped the board, no solution. The Macbook starts up and functions with an external monitor. If I look very hard, I can see the menu bar at the bottom of the LCD. What other trouble shoot can be done to get the LCD back on?
Thanks RandyW.

Answers

  • Contrary to popular belief, inverters almost never go bad. They are simple devices, like a modem, and there's really not a lot that can go wrong with them. If someone tells you the problem is the inverter itself, chances are they have some book knowledge but do not have a lot of real experience repairing computers. More likely, the problem is the inverter cable, the screen itself, or even the backlight circuitry on the board.

    What model MacBook do you have, i.e. aluminum (silver keys), or unibody (black keys)? From the $100 price, I'll assume it's an aluminum.

    First, I would reset the PRAM. This sounds very basic, and it is, but often the screen brightness is all the way down, and this is easily confused with a hardware problem. Resetting the PRAM will put the screen brightness back to the default setting.

    Next, see if the screen flickers or comes on at any point when you flex the screen on its hinge. If so, that's evidence the inverter cable is being crimped. If not, it doesn't mean it's NOT The inverter cable -- it may just be crimped beyond the ability to work at all. But if it does flicker specifically when the hinge is moving, you know it's the cable.

    I would also shine a flashlight through the Apple symbol from behind the screen in order to determine if the screen is cracked, etc.

    But generally, for an aluminum, I would start by replacing the inverter cable. You can search eBay for "A1150 inverter cable" (replace A1150 with whatever your model number is -- you can find it on the underside of the machine). If that doesn't do it, it's most likely the screen itself. Honestly there's a greater chance it's a screen than the cable, but the cable is cheap and the screen it's expensive, so I always start with the cable, hoping to get lucky.

    Anyway, good luck, and let me know how it goes!

    John
  • The Macbook Pro is the aluminum with silver keys. I tried the PRAM reset, and was unsuccessful. I will continue to trouble shooting the Backlight issues.

    I moved the inverter cable around to see if there was any short. Nothing came up on the monitor.

    I will try to trouble shoot by testing the the backlight and cable
  • I tested my LCD/Display on another Macbook Pro A1150 silver keys. The display works fine. Although there is pixelization issues with the test macbook pro, another future project.

    I tried another keyboard assembly, and no luck with pressing the brightness key.

    I held down the "alt / Option", "apple" , "P" & "R" key at the start up. This would cause the another restart. Is this correct for doing the "Reset PRAM"?

    Could it been the inverter connector on the logic board?

    RandyW
  • edited June 2012
    When you say you tested your LCD/Display, do you mean you tested your entire screen assembly on the other machine, including the same inverter cable, inverter, hinge, etc.? If you moved the whole assembly and it worked, that rules out the inverter cable, as well as the screen, inverter, etc.

    If you just moved the screen itself and not the entire assembly, then the next step should be replacing the inverter cable, because that is the only part you have not ruled out.

    But assuming you swapped the whole assembly, I would have to say it's likely the backlight circuitry on the board. It's not generally the connector, but rather hardware deeper within that plays a part in producing a backlight. If this is the case, there's not a lot that can be done.

    It's a longshot, but if you have two A1150s, you might consider swapping the left IO board (the small board with the ports to the left of the logic board) between them. This is responsible for many power functions, and it's conceivable that it is faulty. I don't recall a left IO board replacement resolving a backlight issue, but then again it's really the only remaining step you can take before replacing the board itself, so if you have two A1150s, you might as well try it. Also, make sure all the various connectors around the left IO are secure, since there are many, and a loose connector can produce any given result. If you need a guide to removing the left IO, they have one over at ifixit.com.

    Yes, as far as resetting the PRAM, the screen should stay black, and it should produce a chime sound every 10-15 seconds. If the screen lights up, it means you didn't hold down the keys quickly enough.
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