iPhone X can not be charged fault repair

Machine model: iPhone X
Malfunction: The mobile phone can’t be charged. There is a charging icon, but the more it is charged, the less it is.

iPhone X can not be charged fault repair Figure 1.

iPhone X can not be charged fault repair Figure 2.

Maintenance process: actually, the lighting cable plug-in can be recognized, and there is a charging icon but no charging current. This fault is caused by a problem with the charging chip or the charging circuit. After excluding Accessories, insert lighting cable to measure whether the battery interface VCC exists, and determine that it is the motherboard problem. Directly observing the motherboard separate, we found that the charging chip and the upper L3341 and L3340 had been replaced by the previous home.

iPhone X can not be charged fault repair Figure 3.

After re-processing the place that was moved last time, the test failure of the upper test rack remains the same. When the charging chip is removed, it is found that A1 to F1 pin do not have diode value. These pin are PP_BATT_VCC batteries VCC.

Boardview shows that PP_BATT_VCC is connected to Q3350.
According to past maintenance experience, Q3350 can be short-circuit, directly short-circuit B2, C2, B3 and C3 pin. Test diode value back to normal again, installation test still doesn’t charge. Then remove the charging chip, carefully measure and find H3 pin pin. Check schematic, which is TIGRIS_LDO.

iPhone X can not be charged fault repair Figure 4.

It can be seen from schematic that this signal is directly connected to two Capacitor externally. With 4V VCC, it is found that Colophony (Solder)on C3361 melted first.