HP DM1 Laptop Doesn’t Boot, +VCC_CORE Voltage Missing

A HP laptop doesn’t boot, press power button, the current 0.35A stopped, According to experience, doubt power supply for cpu problem. So test +VCC_CORE (PL13), found +VCC_CORE voltage missing. Observe carefully, there is a small hole on the lower mosfet PQ26, it was damaged. Removed PQ26, test the resistance between PL13 inductor and gnd, the value is normal.

So, replace a new PQ26, connect power and boot again, the current still is 0.35A and stopped. Touch power ic RT8165B, very hot, suspected it was damaged, so replace a new RT8165B. Boot again, the current 0.20A stopped, +VCC_CORE voltage missing, yet. Take the schematic diagram, test +VIN, VCC, PVCC, EN, etc,...read more