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820-00281 No power

T

tcampbell34

Member
Hello. I have a 820-00281 that is not liquid damaged, and the board looks completely clean. When I connect the charger it goes to 20v .380a and just stays there. CPU and GPU voltage is not present but all the main rails seems to be fine. All_SYS_PWRGD is 3.22v. I compared diode mode values on all the big coils with a good board and they seem fine. Here are some of the voltages I have measured.

ALL_SYS_PWRGD - 3.22
SMC_DELAYED_PWRGD - 3.41
PM_PCH_SYS_PWROK - 3.31
LPC_PWRDWN_L - 0
PLT_RST_L - 0
CPU_VCCST_PWRGD - 0.976
CPU_VR_EN_R - 3.22
PPVCC_S0_CPU - 0
PM_DSW_PWRGD - 3.41
PM_PCH_PWROK - 3.32

L7030 - 12.66
L8000 - 1.012
L7960 - 0.964
L7900 - 1.2
L7600 - 5.14
L7660 - 3.3
L8410 - 0
L7410 - 0
L7420 - 0
L7211 - 0
L7221 - 0
L7231 - 0
L7330 - 1.053
LA640 - 0
LA650 - 0
LA350 - 0
LA300 - 0
LB700 - 0
L3500 - 0
 
T

tcampbell34

Member
Sorry forgot L8020.

L8000 - 1.012
L8020 - 1.8

I checked the voltages on all the outputs on page 74 and they are all present.
 
2informaticos

2informaticos

Administrator
Staff member
Missing PPVCC_S0_CPU can be caused by bad PCH, or CPU.
However, try known good BIOS, as it is also involved there.
 
T

tcampbell34

Member
Yea I think its the PCH. I noticed after leaving the board connected to the charger for a few minutes, the PCH seems to get warm. The CPU does not feel warm at all. I have never replaced a chip of this size before. It it something that can be done using just the Quick 861DW or I will need some kind of rework station?
 
T

tcampbell34

Member
Update on this one. I replaced the PCH on this board but I still have the same exact symptoms, so I don't think it was a PCH issue. The new PCH also gets warm though, as if there is a short to ground somewhere. I can't seem to find any shorts. Could a bad CPU cause the PCH to heat up?
 
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