The MacBook family was first introduced in May 2006 and replaced the iBook as Apple's consumer laptop.

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A1181 No Backlight & no power on Pin 4 backlight connector

I have a Macbook A1181 with the 820-2279-A Logic Board and 13" display that the backlight is not working.

I know the display works being when its on, you can see an image on the screen but its very dark to see.

I purchased a replacement inverter thinking that was the problem but still no backlight. My only issue is could it be that the replacement inverter I got is bad as well? I really don’t know how I can test if the inverter is exactly supplying voltage on the other end that the LCD plugs into? Being if I plug a volt meter into that end won’t it fry my volt meter?

I was able to finally figure out a way to test to see if the backlight was bad on the Macbook screen itself. After plugging that into another spare laptop, it does light up. I did try plugging a spare screen monitor into the Macbook and it doesn't light up.

I tested the 4 wires coming from the backlight connector on the logic board and I do get the same reading from the board to the other end of the connector which confirms the backlight harness is good. However I saw a post with what voltage I am supposed to see from the Backlight connector.

pin1 (right side): 12V,

pin2 : ground,

pin3: 5V,

pin4 (left side): 3.3V.

While the laptop is running with a volt meter I do not get any voltage from Pin 4 which is supposed to be 3.3v? Is this the reason why I am not getting any backlight to my screen? Is there a resister or something causing this not to supply voltage to this pin causing the backlight not to work? Any tips on what I should check/replace would be greatly appreciated.

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Michael Dougherty, pin 4 is coming from the backlight power management. Check the AND gate U9053 as well as coil L9001. Ultimately, it does sound like a bad inverter, and you better not test it with a conventional multimeter due to the high AC voltage.. If you need to identify the components, post an image of your logic board with your question. Hope this helps, good luck.

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