Macbook A1466 PPBUS at 8.2V

[Instafixx]

820-00165 - No magsafe Light. No Fan Spin. PPBUS at 820-00165.
SMC is already reballed ( or perhaps changed).

PPBUS at 8.2V is SMC isnt running.
Should we just replace the SMC or we can check other parameters first

 

[2informaticos]

Did you check SMC_RESET_L at least?
Also check SMC's basic voltages, page 37; U5000 (2 OF 2).

 

[Instafixx]

SMC_RESET_L is 0.1V

Do we need to check other or Replace Voltages.

No Short to Ground on SMC_RESET_L.

Resistance Across Pins on R5100 is 15k Ohms.

 

[2informaticos]

Disconnect U5100 and check if goes high.

 

[Instafixx]

You mean U5110?

 

[2informaticos]

Yes, sorry for typo...

 

[Instafixx]

Yes it goes high after removing U5110.
Get Magsafe Light as well now.

Update : I just rechecked it after like 3-4 hours.
SMC_RESET_L again back to 0.1V.

Was it that the board was a bit warm that time and showed different results?
To verify, I just put some flux on the area above the SMC (R5115 Area) and heated it with the hot air gun.
Again started getting Magsafe Light and SMC_RESET_L went high.

Cooled it down again and again it went missing. Weird

 

[2informaticos]

Do you mean that SMC_RESET_L goes off, after some time, even when U5110 is removed?

 

[Instafixx]

Yes. SMC_RESET_L goes low if the board when the board cools down. If i heat up the area mentioned above it goes high.
All of this when U5110 is removed. I did this twice.

 

[2informaticos]

Inspect J6100 for corrosion; you can even remove it.

Force the signal with 10K, instead of 100K (R5100).
If still happens, remove R7100 and check again.
Reballing/changing SMC is the last option.

Once signal is stable, resolder U5110.

 

[Instafixx]

After removing JTAG connector it was stable for a while. Put back U5110. Machine is on now. Let me use it for a day.