Apple Macbook Air A1466 Laptop with Sometime Cannot Power On Problem  

Repair this type of laptop problem is very hard to fix it, but after you know how to troubleshoot and repair it, sometimes it can be an easy repair job too. Come in an Apple Macbook A1466 laptop with complaint very hard to power on or sometimes can power on, but sometimes cannot.  

This Apple Macbook A1466 laptop when it can power on/start up, sometimes will appear no display, the fan rotates a while then stop, after fan stop it will start to rotate again. 

When the laptop power on the fan will rotate, when the laptop cannot power on/startup, their power on current will stuck in between 0.16A~0.26A.  

Because of this laptop can power on, that’s mean it can trigger. So check the laptop mainboard each output voltage inductors. All the output voltage inductors have the normal voltage there, except the CPU voltage supply no output. Follow by checking their Mainboard chips PG (Power Good) signals appear or not. When check the U7600 chip PG signal line, found in between the P1V05S0_POOG and ALL_SYS_PWRGD line resistor R8164 missing! This laptop was repair or check by another repairer before, and the laptop mainboard looks like watermarking there.  

Search the Apple Macbook laptop schematic diagram and found this R8164 resistor values is 100K ohm. Try to put back a good 100K ohm resistor in R8164. But the laptop still the same problem.

Continue to check the U7600 and their corresponding components, all are in good condition, but their PG signal still not appear. Again, refer to the schematic diagram, U7600 PG signal is come from R8164 push up of U7600 pin-2 ALL_SYS_PWRGD, then SLP_S3 push up to 3V. So use the multimeter check their line continuity from in between the R8164 to other ALL_SYS_PWRGD signals lines. Found the line continuity to ALL_SYS_PWRGD was broken! So use the nearby ALL_SYS_PWRGD signal point connect it with a wire to R8164. Power on the laptop and the CPU voltage supply is appear now!

Finally, the Apple Macbook Air A1466 laptop problem solved!  

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Laptop Chip Level Repair Guide