[SOLVED]820-3115 Voltages present minus PPVTT_S0_DDR_LDO

[bjf]

Scattered liquid-damage. Everything is present on this board except PPVTT_S0_DDR_LDO. DDRVTT_EN (MEMVTT_EN) is not present. I've repaired main power circuit, replaced BIOS just in case. Everything about this board seems in order other than that one voltage (and the voltages that would come after it - CPU etc.) I haven't seen this one before. Any ideas would be greatly appreciated. I've attached pictures. They get shrunk pretty bad by the forum uploader but it might help a little.

 

[dukefawks]

What is voltage on PLT_RST_L? If it is high then MEMVTT_EN should be pulled high through R2810.

 

[bjf]

0V on PLT_RESET_L\
I'm trying to dig and see where this comes from and why I might not be getting this voltage. Nothing so far.

 

[dukefawks]

Is CPU Vcore present?

 

[bjf]

No, it looked like CPU Vcore required PPVTT_S0_DDR_LDO to be present. I thought I would need ALL_SYS_PWRGD in order to get CPUIMVP_VR_ON to enable U7400. Is that not true, is this just a CPU Vcore issue? I have 0.50V on CPUIMVP_VR_ON.

 

[dukefawks]

Well, you need to figure out why there is no ALL SYS PWRGD. U7300 is excluded from that, so some other voltage must be missing.

 

[bjf]

Thanks, got it. I missed the fact that PVCCSA_EN was not present. Replaced U7600 and Q7100 and it's up and running. Thanks for your help.