Dear members,
I have a GA-945GCM-S2L mainboard that I am fixing. All voltage rails are fine in this mainboard, except for VTT_GMCH.
When CPU is out of the board, VTT_GMCH is fine at 1.22v. In this case, we have:
Pin1 of Q287: 1.22v
Pin2 of Q287: 1.5v
Pin3 of Q287: 1v
Pin4 of U85: 12v
Pin5 of U85: 1.22v
Pin6 of U85: 1.22v
Pin7 of U85: 1v
VTT_PWRGD: 1v
CPU_VCORE: 1.06v
resistance on VTT_GMCH: 200 Ohms.
When CPU is inserted, VTT_GMCH is low at 0.2v. In this case, we have:
Pin1 of Q287: 0.4v
Pin2 of Q287: 1.5v
Pin3 of Q287: 0.2v
Pin4 of U85: 12v
Pin5 of U85: 1.22v
Pin6 of U85: 0.2v
Pin7 of U85: 3.6v
VTT_PWRGD: 0v
CPU_VCORE: 0.0v
resistance on VTT_GMCH: 9 Ohms.
I have tested it with 3 CPUs (two Celeron-D CPUs and one Pentium 4 CPU) and the mainboard has this same problem.
I have replaced Q287 and EC169 but the problem persists.
I did not replace U85 because I think it is working correctly.
What do you think is the problem?
Thanks
I have a GA-945GCM-S2L mainboard that I am fixing. All voltage rails are fine in this mainboard, except for VTT_GMCH.
When CPU is out of the board, VTT_GMCH is fine at 1.22v. In this case, we have:
Pin1 of Q287: 1.22v
Pin2 of Q287: 1.5v
Pin3 of Q287: 1v
Pin4 of U85: 12v
Pin5 of U85: 1.22v
Pin6 of U85: 1.22v
Pin7 of U85: 1v
VTT_PWRGD: 1v
CPU_VCORE: 1.06v
resistance on VTT_GMCH: 200 Ohms.
When CPU is inserted, VTT_GMCH is low at 0.2v. In this case, we have:
Pin1 of Q287: 0.4v
Pin2 of Q287: 1.5v
Pin3 of Q287: 0.2v
Pin4 of U85: 12v
Pin5 of U85: 1.22v
Pin6 of U85: 0.2v
Pin7 of U85: 3.6v
VTT_PWRGD: 0v
CPU_VCORE: 0.0v
resistance on VTT_GMCH: 9 Ohms.
I have tested it with 3 CPUs (two Celeron-D CPUs and one Pentium 4 CPU) and the mainboard has this same problem.
I have replaced Q287 and EC169 but the problem persists.
I did not replace U85 because I think it is working correctly.
What do you think is the problem?
Thanks
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