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Lenovo IH81M mainboard no power on repair.
Lenovo IH81M VER: 1.0 motherboard no power on, replace c453 U40, the fault is removed.
Machine model:Lenovo IH81M VER: 1.0 ms-7825.
Fault phenomenon:no power on.
Maintenance process: directly measure rsmrst (standby good signal) 0V is abnormal, and then find PCH at the front level_Dpwrok deep sleep signal is easy to find, but 0V is still not detected.Forward measurement + 3vsb_3 V was normal by DSW.
Lenovo IH81M mainboard no power on repair Figure 1.
Find U40 is sending out PCH_Dpwrok signal.The real picture is as follows:
Lenovo IH81M mainboard no power on repair Figure 2.
U40 working condition: U40 5 pin VCC 3.3V normal + 3vsb_Provided by DSW.The 0.9V of 1 pin is abnormal, the 0.9V of r635 is abnormal, 3.3V of r635 is normal, c453 Capacitor 1 pin VCC is normal after blowing off c453 Capacitor.
Lenovo IH81M mainboard no power on repair Figure 3.
Lenovo IH81M mainboard no power on repair Figure 4.
Afraid of high temperature impact on U40, in order to stabilize the replacement of c453 U40, troubleshooting!
