Gigabyte B250-HD3 does not have CPU power supply repair

Gigabyte B250-HD3 does not have CPU power supply repair

Gigabyte B250-HD3 does not have CPU power supply , replace with a new CPU, the fault is removed

Machine model: Gigabyte B250-HD3 REV:1.0

Fault phenomenon: No CPU power supply

Gigabyte B250-HD3 does not have CPU power supply repair Figure 1.

Maintenance process: the mainboard is not reset, and each VCC is normal, that is, there is no CPU VCC.The power management of each chip is 866_Ready is normal, 3.3V is sent to io.IO is it8686e and VR from PWM is received_After RDY, n will be issued_PCH_Vrmpwrgd, the measurement found that 1.7V is abnormal.N_PCH_Vrmpwrgd is 3.3V pull-up, and then converted to CPU through partial voltage_VCCST_Pwok to CPU.

Gigabyte B250-HD3 does not have CPU power supply repair Figure 2.

Gigabyte B250-HD3 does not have CPU power supply repair Figure 3.

Either the problem of pulling up or there is a place for Short circuit to pull down n_PCH_VRMPWRGD。short-circuit nr122 can output CPU VCC by pulling 3.3V. It seems that the fault point is here. If the nr127 NBC1 is removed, the fault is still the same. If the nr122 is removed, 1K is normal. If the EC is disconnected, the fault is still the same.

After disconnecting wr34, it finally recovered to 3.3V, which seems to be the CPU_VCCST_Pwok lowers n_PCH_VRMPWRGD。CPU measurement_VCCST_The pwok value is 1.7V, which is abnormal. The normal partial pressure should be 1V. The measured wr34 is only dozens of ohm, and the normal value should be 6.04k. Replace the wr34 and return to 1V.N_PCH_Vrmpwrg will not be pulled down again.However, there is still no booting up, the CPU has been broken, the replacement CPU finally lights up, and the fault is repaired.Wr34 is very easy to deposit ash under the CPU corrode, which may become common failing.

Gigabyte B250-HD3 does not have CPU power supply repair Figure 4.