ASRock B75 Pro3 motherboard does not run code when powered on

Main board No.: ASRock B75 Pro3 Rev: 1.03

Fault phenomenon: the main board does not run out of code when powered on and has no reset

Maintenance process:

A B75 Pro3 motherboard of ASRock, the fault is that the power on test does not run out of code. It is measured that CPU VCC is available, reset is not,CLK is.

ASRock B75 Pro3 motherboard does not run code when powered on Figure 1.
Open Boardview and check the time sequence. It is found that the reset is sent by the bridge after the CPU chip VCC is given to PG. it can be seen that 39 and 40 pin of Boardview 8859 are pulled up by 3V, and the measurement is only 0.5. It is judged that the wire is broken.

ASRock B75 Pro3 motherboard does not run code when powered on Figure 2.
Jump wire by VCC.

ASRock B75 Pro3 motherboard does not run code when powered on Figure 3.
After flying the line,switch power supply started and stopped for a while, and then it was powered on automatically again, indicating that the machine was successfully reset and the sound of buzzer was heard.Plug in the memory,Normally booting up.This is the end of the repair.