Lenovo ThinkPad X1 Yoga laptop can't be charged and repaired

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired

Machine model: Lenovo ThinkPad X1 Yoga

Main board number: 14282-2M

Malfunction: The laptop does not charge.

Maintenance process:

A Lenovo ThinkPad X1 Yoga laptop failed to isolate Current protection. After disassembling, it was found that BQ24780S charging chip burned, many Fuse were broken, and two 20-ohm Fuse resistors were also broken. Replace a charging chip and connect all the broken Fuse. The adapter can be turned on, or it can be turned on with battery, but the computer is not charged. After unplugging the charger, it still shows that the adapter is connected.

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired Figure 1.
Check the working conditions of the charging chip first. Some drawings of the charging chip are as follows:

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired Figure 2.
Here is an output of adapter status. After measurement, it is 3.3V whether the adapter is plugged in or not, which is obviously problematic. Check the manual of this chip.

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired Figure 3.
When the pin of ACDET is greater than 2.4v, the acok level is high, that is, 3.3V On the contrary, if the pin of ACDET is less than 2.4V,ACOK is at low level, that is, 0V.
Then measure ACDET, which is 11.3V when there is no access adapter, and as high as 15.4V after access adapter.

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired Figure 4.
VCC of ACDET is obtained by dividing the common point VCC by these two resistors. Measure these two resistances. When R7117 (66.5 kω) is measured,diode value exceeds 10MΩ. After washing and soaking with Cleaning solvent, it was found that a corner was broken.

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired Figure 5.
It is the resistor of 0201 package, and its volume is very small. I found a pile of resistors to make this ratio.

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired Figure 6.
According to the power-on test,VCC is normal. No adapter is plugged in at 1.7V and 2.6V, but the ACOK signal is still 3.3V Check the charging chip manual.

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired Figure 7.
It is found that the maximum pin of ACDET is 7V, and the measured VCC is larger than this VCC, so the charging IC must be dead.
Replace the charging chip and the resistor of the same type.

Lenovo ThinkPad X1 Yoga laptop can’t be charged and repaired Figure 8.
Power-on test, charging is all right, it will be charged to 97% in a moment, and the repair is completed.