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Released June 2012, Model A1278. Intel processor with Turbo Boost, Up to 512 MB DDR5 Video RAM

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no backlight after water damage.


You're doing great job here!

I would like if you could help me too.

I have Macbook A1278 with 820-3115-B motherboard after water damage.

There is no backlight of screen (flashlight trick works) and keyboard. I check voltage :

I2C_BKL_1_SCL 3,3V at R9753

I2C_BKL_1_SDA 3,3V at R9757

LCD_BKLT_PWM 3,3V at R9704

PP3V3_S0_BKL_VDDIO 3,3V at C9711

PPBUS_SW_BKL 12,4V at C9712

PP5V_S0_BKL 5V at C9710 and C9714

PPBUS_S0_LCDBKLT_FUSED 12,4V at F9700 and on out Q9706

PP3V3_S0_LCD 3,3V at R9008 and R9009

PP3V3_LCDVDD_SW 3,3V at L9004


PPBUS_SW_LCDBKLT_PWD 12,4V at R0910 and then 3,06V at R9715

and there it 0V at BKL_ISEN1,..,BKL_ISEN6, so this is mean that U9701 need to be replace?

Albo Magsafe works 1 on 5-10 tries. I have to plug it slowly and then there is green light and it starts (no battery inside).

Please help me with backlight and connector.

Thanks in advance.

PS: Sorry for my english

Answer this question I have this problem too

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Did you check Q9707 to see if the backlight gets enabled?


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1 Answer

Usually, the backlight fuse always gets blown. Replacing F9700 ought to do the trick. There should be roughly 10-12.4V on both sides of the fuse if it's working properly. If it was blown, you'll get no voltage on one side of it. Thus, the backlight will not activate.

The fuse looks something like this image.

In terms of the MagSafe problem, I would just clean everything up with denatured alcohol. Make sure everything's clean and there isn't any gunk between the contacts.

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There is 12.4v on fuse and it's doesn't blow. I'll try clean connector better. Thanks for will to help.


I've clean it but this doesn't help.


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