
repair of Apple MacBook Pro A1708 Notebo…

It is found that the 83-pin of EC is ALW_ON, the measured resistance is normal, and there is no voltage output at this pin after power-on, which is the problem of EC. Measuring pin, there is already a voltage of 3.3V Short-circuit the switch, and the current reaches about 1.5A Install the machine, plug it in, start it up, and turn it on perfectly. Troubleshooting, the maintenance is over.

Check the main power supply of 24780. According to Manual 24780, the output of 24-pin REGN 6-V linear regulator is provided by VCC. The LDO is active when ACDET is higher than 0.6V and VCC is higher than UVLO. After changing PR4413 to 10 ohms, the fault was eliminated and all problems were solved.

1 pin EN is normal, 23 pin Vin has no voltage to ground resistance of 0 ohms. After tracing forward, it is found that a current limiting resistor is burned, and a small capacitor is short-circuited behind the current limiting resistor. Find a small resistor of 10 ohms and a small capacitor, and the boot is normal.

Lenovo Xiaoxin Air 14IKBR laptop has a dark screen, traced it to Q1, measured the breakdown short circuit of 2-3 pins, removed the corresponding Q1 tube and insurance on the material board, and turned it on perfectly after the replacement.

Lay down the chip value and find that several pin values are abnormal. Measuring the upper and lower tubes shows that the extreme values of G and S of the upper tube are 50. Replace the chip and the upper tube. Power-on standby is normal again, 0.014A triggers 0.073A is normal, the machine is powered on, the machine is turned on perfectly, the fault is eliminated, and the maintenance is over

Lenovo Y700-14ISK notebook screen does n…

Repair of Dell G3 579 laptop without cha…

Lenovo ThinkPad X1 Yoga notebook compute…