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Go Back   GSM-Forum > GSM & CDMA Phones / Tablets Software & Hardware Area > iPhone ,iPod & iPad (Apple Inc. Products) > iMac, Macbook Pro, Macbook Air

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Old 11-02-2018, 10:33   #1 (permalink)
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Thumbs up [Solution] How to repair Macbook no display?


Situation:
MacBook air black screen issue during system boot. Instead of a traditional blue screen, the MacBook air is booting to a completely black screen with the initial “chime” sound. And keyboard backlights are also on. Which means the MacBook is on, well supplied by power and runs normally, and you just can’t see that it is.

You can repair Macbook no display as following:
Disassembling
Power button power up. The MacBook is booted to a completely dark screen. Yet keyboard backlights are on, which indicates that the MacBook is on with no screen display. Disassemble the MacBook. Disconnect flex cables and remove screws. Then detach the logic board and remove the SSD and WiFi modules.



Diagnosing
Run a cosmetic inspection—whether there are mildew, component missing or burnout on the logic board. No particular damage.



The test grounding resistance value of fuse F7700 with diode mode and the value proves to be normal.




Then connect AC adapter and test voltage value of fuse F7700, the displayed value is 8.58V—normal value.



Test grounding resistance value of logic board display port pins with diode mode. All display normal value. A test grounding resistance value of backlight resistors with diode mode. All display normal value.



Connect AC adapter and test voltage values of display chip U7701 and nearby components. BKL_SCL displays abnormal voltage value (3.3V under normal circumstances).



Roll out the maintenance bitmap and locate BKL_SCL. Confirm the corresponding resistor as R7753. Then roll out the circuit diagram. Analyzing the circuit network, we find that SCL is connected to pin D3 of U7701 via resistor R7753. Then we can infer that U7701 might broke down.





Repair
The detail steps to repair Macbook no display click here
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