820-4924: No PP5V_S4

[macRepairAmb]

Have this board that came in with some corrosion damage and wasn't powering. Clean up the corrosion and replaced any corroded components, but still not powering up. What i get is two pulses on PP5V_S4, and even ALL_SYS_PWRGD at initial point of connecting the MagSafe.

No activity on smc bypass.

PM_BATLOW_L 3.3V
PM_RSMRST_L 3.3V
PM_PWRBTN_L 3.4V
SMC_ONOFF_L 3.4V

Attempted triggering SMC_ONOFF_L while checking PM_PWRBTN_L and PM_PWRBTN_L doesn't change. Remains at 3.4v.

Any suggestions

 

[2informaticos]

Check all SPI Bus Series Termination resistors and their traces.
Clean/remove J6100, if needed.

 

[macRepairAmb]

All SPI bus resistors and traces good.
No change after removing J6100

 

[2informaticos]

Try another SMC then...

 

[macRepairAmb]

Same result with another smc.

 

[2informaticos]

Do you get steady 3V3_S5/SUS?

Check for correct oscillation at Y5110.

 

[macRepairAmb]

no clock oscillation at Y5110 just DC voltage at pin 1 @ about 1.5v.

 

[macRepairAmb]

what could cause PM_PWRBTN_L not to respond when SMC_ONOFF_L is triggered? I've replaced the SMC with the same result.

 

[macRepairAmb]

o-scope only showing DC signal. On a good board, it's about 1.35v.

U5000 measurement:
PP1V2_S5_SMC_VDDC - 1.2v
PP3V3_S5_AVREF_SMC - 3.3
PP3V3_S5_SMC - 3.4
SMC_RESET_L - 3.38
SMC_WAKE_L - 2.9
SMC_CLK32K - 32.77k

 

[2informaticos]

Y5110 should have 12MHz oscillation.
If not, check its components and traces.
You may need to change SMC.