ASUS B85M-F fan runs normally, and it is not lit for repair

The ASUS B85M-F fan is always running, the light is not lit, the BIOS is brushed, the PQ804 is removed and replaced with a new one, but the fault is still the same, so the PQ801 is removed and connected to the PQ800 through a 10K resistor, and the PQ800 is replaced with a new one, and the fault returns to normal.

Machine model: ASUS B85M-F

Fault phenomenon: after triggering, the fan keeps rotating and the light is not on

Maintenance process: Get the machine, measure that all the major voltages are normal, and the CPU power supply is also out. First, brush the BIOS, and the fault remains. Next, check the power management chip. The chip is ASP1252, and the 10 pin is a PG signal. After checking the PQ804 along the 10 pin, it is found that it is broken. Replace it with a new one, start it, and find that the fault has changed. The fan will stop after a few seconds, and it can be triggered again.

Dismantle PQ801, the tube controls the EN voltage and lights up successfully after triggering. It can be seen that a new fault point appears after heating, because the EN was normal before. The PQ801 is connected to the PQ800 through a 10K resistor. After removing the PQ800, it is found that it is also damaged. After replacement, the machine starts up and everything is normal.