820-00164 quarter fan spin

[PhilipC]

Have a macbook air 11" 2015 that was working, was in a middle of installing sierra and suddenly turned off (it was plugged in). Now does not want to turn on (quarter fan spin orange then green then orange light). Tried disconnecting battery and still the same. Reflowed SMC - same. Replaced R7121 and R7122 as they were reading 100ohms instead of 10. Replaced U6100, U5110 and C5101 and still nothing. Wasted half of my day on this. Any ideas? Would appreciate it. P.S. tried a different dc-in board already

 

[dukefawks]

Put back original U6100 first!! U1950 pin 8 inspected? U6100 termination resistors checked? Was this liquid? Vcore pulsing too?

 

[PhilipC]

Put back original U6100 first!! U1950 pin 8 inspected? U6100 termination resistors checked? Was this liquid? Vcore pulsing too?

Forgot to mention. Original U6100 has been put back.
U1950 pin 8 reads 5v
U6100 termination resistors checked all good
No liquid damage or at least no signs of any. (no corrosion)
vcore reads 1.8v then goes back to 0

 

[JohnB8812]

Pin 8 should be 3.42 not 5 there is possibly the problem

 

[PhilipC]

Pin 8 should be 3.42 not 5 there is possibly the problem

replaced it, 3.42v now but problem still remains

 

[dukefawks]

Vcore still pulsing? How long does it stay on?

 

[PhilipC]

Vcore still pulsing? How long does it stay on?

measures 1.81v when the fan is spinning then goes off to 0v and fan stops and stays there
fan stays on for like half a second but reading 1.8v goes off almost immediately after the fan starts

 

[dukefawks]

Any history on this thing? Seems unlikely it "just" failed installing. That chance is smaller then winning the lottery.

 

[PhilipC]

client said that it was turning off randomly - "used to happen very rarely then started happening more and more often" then that's when i tried to re-install the OS and crashed mid-way and never started after that. No liquid damage. She said that she used to carry it in her rucksack all of the time but was careful

 

[dukefawks]

Yeah if this thing has no signs of liquid damage it could be anything. Probably has been banged and flexed in that bag for years. Some cracked trace/ball somewhere. This is not worth messing with, sorry.

 

[PhilipC]

Yeah if this thing has no signs of liquid damage it could be anything. Probably has been banged and flexed in that bag for years. Some cracked trace/ball somewhere. This is not worth messing with, sorry.

do you think it's worth replacing the SMC at this point? as that's the only thing that I haven't done to this point

Edit: Replaced SMC and still the same. Guess it's just a short in one of the rails. Thank you for trying anyways.