08 Sep

MacBook Air Liquid Damage:

MacBook Air 13 inch, Model A1466, the Year 2015, Logic Board Number 820-00165. This MacBook Air laptop can be powered up and chimes but no display. The customer could see the dim image by shinning a touch from the Apple logo to the screen. Three computer shops had failed to repair this Mac laptop. The staff of the last computer repair shop told the customer that the LCD screen also got damaged and the customer could not see the dim image any more.

MacBook Air Faults Diagnosis:

This is a typical “no backlight” issue of MacBook Air laptop. As a new MacBook Air screen will cost about $500, our first task is to check whether the LCD screen is working or not. By connecting a working MacBook Air logic board to the screen, we confirm that the screen is fully functional. Then we inspect the logic board and find something immediately.

The LCD 3.3V power supply circuit has been burned as shown in the above photo. Further measurement confirms that it was caused by a shorted circuit in the screen connector.

MacBook Air Repair:

  1. Replace the screen connector and all burned components.
  2. Use a multimeter to measure the connector pins to make sure there is no any shorted circuit.
  3. Connect the MacBook screen to the logic board and power up the Macbook, we can see the dim image now, but still no backlight.
  4. The backlight power rail is generated by a chip on the back of the MacBook Air logic board. Let’s have a look:

There is something underneath the backlight chip U7701. Let’s have a close look using a microscope.

There is a bug dropping! Two of the solder balls underneath the chip had gone due to the corrosion. Replace the chip we have backlight now. Job has been done.

MacBook Air Repair – Conclusion:

There was a bug dropping in this MacBook Air. The bug dropping corroded the backlight chip and caused the “no backlight” issue. Someone thought the no backlight issue was caused by a blown fuse. Then he used a large amount of solder to bridge the fuse even though the fuse is working perfectly. Somehow he managed to short the pins of screen connector and burned the 3.3V power rail, resulting in more damage – no image at all. Luckily, the MacBook screen did not get damaged. If the screen is damaged, this MacBook Air Laptop will be classified as “not economically repairable”.

IT-Tech Online offers advanced MacBook repair in Melbourne. We provide postal Mac repair services to customers Australia wide. Call us on (03) 9563 8588 to get your MacBook fixed today.

Note: U7701 is the chip number of Apple MacBook Air schematics 820-00165.

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