General

Quarter Fan Spin (QFS)
    CPU VCore
        ca. 6 ohm to ground
        Missing CPU VCore - check RTC circuit
    Quarter fan spin (QFS) means S0 state rail problem
    U7200 solves a lot of quarter fan spin (QFS) problems.
    Check PP5V_S5 for pulse
    Check PPBUS_S5_HS_COMPUTING_ISNS
    Check U7400 for CPUIMVP_TON
    Check U7400 for CPUIMVP_VR_ON
    Check for ALL_SYS_PWRGD (pulsing NOT good)
    Check P1V05_S0
    Check S0 rails for pulsing

ALL_SYS_PWRGD Pulsing
    

RTC
    Pulsing output can cause QFS
    check 3.3V

Pros

0.5 to 0.7 Amps is all good
PPBUS_G3H = ca. 8.15V = SMC Reset mode

General board error
    0.2 Amps - short
    0.02 Amps - missing S4 or S5 rail
    0.12 to 0.14 Amps - all rails on but 1 S0 rail missing

Backlight Errors
    0.511 to 0.469 feedback trace on Backlight circuit
    0.2 to 0.3 bad LED driver
    0.565 bad switch trace
    0.519 to 0.496 is good
    0.007 (Diode) broken LCD connector

PM_SLP_S4_L
    0.02 amps missing pm_slp_s4_l
    0.19 short on pm_slp_s4_l


PPBUS_G3H
    12.23v on U7000 (pin 23) no SMC data line on pin 10
    12.56v on U7000 (pin 23) SMC data line on pin 10 is up

820-2849
c9560

MCP Boards
    mcp is pch and gpu
    c7771 should be 1.5v
    c9560 looks like gpu failure




Airs

0.5 to 0.7 Amps is all good

General board error
    2.2 Amps - short to ground
    .025 Amps - missing PM_SLP_S4_L but S5 rails are only ones present
    .085 - .090 Amps - missing rail
    .180 to .250 Amps - All but one S0 rails present

Water Damage
    U1950 bad PP3V42 pad