Released October 2008 / 2.4, 2.53, 2.66, 2.8 or 2.93 GHz Core 2 Duo Processor

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No backlight, can see desktop or images on screen!

Hello Guys,

i have a 2008 MacBook Pro Unibody Model 1286A.

Issue: No Backlight, the desktop images can be seen when shining a flashlight through logo

Things done so far:

1-Replaced LCD screen

2-Reset SMC, PRAM

3-Reseated RAM, tested RAM for function.

4-Have video and backlight on external monitor

5-Swapped out Logic board for used one; still no backlight

- Logic board was supposed to be working

6-Swapped out for another logic board; no backlight again

- Logic board again supposed to be good, but this one was used on machine that had an inverter. mine has no inverter.

Notes; All other functions with Second logic board are Ok.

Any help would be appreciated.

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Roger DeCicco ,"6-Swapped out for another logic board; no backlight again

- Logic board again supposed to be good, but this one was used on machine that had an inverter. mine has no inverter." can't use it with a LED backlit LCD panel. What is your current logic board? Check the 820-XXXX number. Also, what LCD panel are you using. Give us the make/model number.

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Sounds like you either have a bad LED driver or the fuse links are blown on the logic board.

Do you have an DVM to test the fuses? The fuses are similar to the resistors they will have a dot or an O marking and they should be near the LVDS connector.

Update

U9701 is the LED driver. On this board I believe it is a custom Apple driver codenamed GOSHAWK. F9800 is the fuse.

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Dan,

Thanks for the fast response. Some people say that the fuse on this model is on the GPU side of the board approx to the left of the left fan. Maybe you can answer a tech question that is baffling me. On this used board the same model number as the old board 820-2330-A there is a unused connector port in the center of the board not on the GPU side. This connector is empty, on my board there was no connector there. What is it used for? Possibly the inverter for whatever computer the board came from? If so will this board still work for my computer, with no inverter?

Thanks a bunch Dan!

Roger

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I'm not sure I know which connector you are speaking about. Apple has in some versions of logic boards placed automation testing ports so the logic board can be tested during manufacture. I've seen a few boards the port was no longer present (which is why you may find the same exact logic board not have it).

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I would recommend you follow old turnkey as he's more knowledgable with the component level stuff than me. You do need to be careful on swapping things around as you can damage things. In the case of the older CFL backlights they used a high voltage system (inverter) where as the newer models use LED backlights which use much lower voltages but do require a bit more amperage.

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Roger DeCicco, post some images of your logic board with your question. Use this guide Adding images to an existing question to do that. If you post images from both sides, we can most certainly identify the fuse as well as the driver. Then check the fuse for continuity and the voltage on it. You should have `12.6V on it.

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Old turkey,

Thanks for the images. I found the fuse and tested it, and found no continuity. I will be replacing the fuse. However, this is on the old damaged board. I have a tech question on the new/old board purchased. All works except the backlight, I can't test that fuse until I remove it from the machine. This board had been in a machine that had an inverter for the LCD screen. I now have it in my machine which doesn't have and inverter. Do you think this will work, right now it's in and all works except no backlight, but I will be changing the LVDS cable on Wednesday just in case. I also have a new LCD screen in computer. What are your thoughts?

Thanks you for your time!

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