820-00165: Missing PP5V_S4RS3

[macRepairAmb]

Board came in with corrosion on U7600 and U3200. Cleaned and replaced both, but still not powering up.

I'm missing PP5V_S4RS3 - 0v
PP3V3_S5_REG_R is present at 3.3

When attempting smc bypass, the fan spins for twice for about 2 secs each time and then stops.

Any suggestions?

 

[2informaticos]

When in SMC bypass, all voltages try to appear?
Check all big coils and ALL_SYS_PWRGD too.
Be sure to get AVREF_SMC voltage.

Test board alone on the desk; no LIO flex connected, nor trackpad.
Check 3V3_SUS, PM_BATLOW_L and PM_DSW_PWRGD.

 

[macRepairAmb]

PP5V_S0 - tries to come on. Goes up to 0.7 then drops (same as with the fan coming on and off)
All the coils are doing the same thing as PP5V_s0 as the pulse up and down, except the lcd backlight which expected since the display is not connected.
ALL_SYS_PWRGD - goes up to 1.6 before dropping out as well.
AVREF_SMC - 3.3 the whole time. never drops out

Same result with LIO flex not plugged in

3V3_SUS - 3.3
PM_BATLOW_L - 3.3
PM_DSW_PWRGD - 3.4

 

[2informaticos]

"All the coils are doing the same thing as PP5V_s0 as the pulse up and down"
Even L7310/20?

Pin 3/U1950 pulses to?

In normal mode, check SMC_DCIN/PBUS_VSENSE and SMC_DCIN/BMON_ISENSE.

 

[macRepairAmb]

Yes, it also pulses on L7310/20 and Pin3/U1950

SMC_DCIN_VSENSE - 2.8
SMC_PBUS_VSENSE - 0
SMC_DCIN_ISENSE - 0.027
SMC_BMON_ISENSE - 0