GA-B85N Phoenix-WIFI does not trigger repair

GA-B85N Phoenix-WIFI does not trigger repair

GA-B85N Phoenix-WIFI does not trigger, replace IO, 6 pins of BIOS are disconnected from solder joints, fly wires, and the fault is relieved.

Machine model: GA-B85N Phoenix-WIFI

no power on: fault phenomenon

Maintenance process: start fault no power on, visually check that the EC of the main board has been dragged tin, and the nearby resistance Capacitor has been passed by Repeat welding.
The pwrbtn signal sent by EC to PCH was checked by direct positioning. There was no VCC,Measuring diode value and Short circuit.Check that VCC at the other end of pwrbtn pull-up resistor is normal, and the fault is still the same after replacing 8.2k pull-up resistor.Thinking: pwrbtn without VCC is Io bad or PCH bad?

GA-B85N Phoenix-WIFI does not trigger repair Figure 1.
Check the PCH standby and find that the bridge does not send SLP_According to the comprehensive judgment of EC, pwrbtn is most likely to be damaged without VCC io.
This is Gigabyte desktop motherboard, 8 series bridge, before buying new IO, decided to brush BIOS.After brushing BIOS,switch succeeded.When switch was not detected, pwrbtn VCC was normal, and current of change was found after switch.

GA-B85N Phoenix-WIFI does not trigger repair Figure 2.
After switch, the CPU fan turns, CPU VCC has 1.65v, reset 0.2V, but the CPU itself does not have high temperature.Shenma situation, CPU VCC is normal, but the CPU itself is not high temperature, thinking: when there is no reset idea, repair or focus on the CPU module?
Combined with the fault of the machine, after thinking for a moment, it is estimated that 1.65v is the vboot VCC of CPU, which is similar to the old G41 board. There is also CPU VCC without CPU. In view of this fault, it is decided to return to the maintenance origin and focus on bridge inspection.
When checking the standby condition, we find that the SLP of EC is not switch_S3 is 2.8V. Although the main board of switch is powered on normally, but SLP_S3 is still 2.8V, and switch is still the same.I remember that although pwrbtn is normal now, before the BIOS is not brushed, the pwrbtn given by EC to the bridge does not have VCC, so I decided to change io. After switch, the CPU body will soon be high temperature,booting up, and then check the SLP of EC_S3, standard 3.3V.

GA-B85N Phoenix-WIFI does not trigger repair Figure 3.

GA-B85N Phoenix-WIFI does not trigger repair Figure 4.
no power on e rbo is returned to the client, it will be returned to the client_S3 is still 2.7V, and all faults are restored to before repair.It is found that there is something dirty on one of the pin bits of Io. I don’t know if it causes Short circuit between IO pin bits.After several times of power on, the pwrbtn of IO to the ground is 0.After the new Io was replaced, it was turned on normally for many times, and it could not be shut down. The pwrbtn waveform was accurately located. Finally, it was found that the problem was Switch line.

GA-B85N Phoenix-WIFI does not trigger repair Figure 5.
Therefore, dig out the BIOS to verify whether the BIOS participates in switch. The results are as follows:

GA-B85N Phoenix-WIFI does not trigger repair Figure 6.
This machine BIOS dig out,switch,switch cycle auto power off, it can be seen that this BIOS does not affect switch.But found that this machine BIOS 6 pin, unexpectedly and solder joint disconnected, look at the picture carefully.Finally,Jump wire is transferred to 6 pin of the backup BIOS.Switch has been OK for many times. It is OK to install a system. The maintenance is over.

GA-B85N Phoenix-WIFI does not trigger repair Figure 7.