MBA A2179 - No water, No drop - Turned off while working, doesn't turn on. Takes current, no heat.

piernov

Moderator
Staff member
CPU replacement could work, but of course requires BGA rework station, experience with it and a good CPU.
Apparently Apple has a way to recovery data from T2, without needing CPU. This requires access to Apple diagnostic servers, so third-party repair shops cannot do it.
 

samstown

Member
CPU replacement could work, but of course requires BGA rework station, experience with it and a good CPU.
Apparently Apple has a way to recovery data from T2, without needing CPU. This requires access to Apple diagnostic servers, so third-party repair shops cannot do it.
So this is a service Apple propose in Apple store in New York or you need to send it somewhere ?
 

piernov

Moderator
Staff member
I don't think they propose it. I only heard it is possible. Maybe you'll have more luck talking to an AASP, not sure…
 

samstown

Member
I don't think they propose it. I only heard it is possible. Maybe you'll have more luck talking to an AASP, not sure…
I'll investigate. For this MBA, customer said he sent it to big DR Lab and they were asking him for a password... He gave his password but they said it wasn't not the right one however he knows his password... so I wonder what tool they used and what password they were looking for. He finally gave up with the big lab as the communication was bad and he could never speak to an engineer, only sales guy telling him they needed a password.
 

piernov

Moderator
Staff member
Yes the user password will still be needed to be able to read FileVault2 encrypted volumes. Maybe he gave EFI password or something else that's different.
 

2informaticos

Administrator
Staff member
"I wrote 0 Ohm, they have 0,4 Ohms to be exact."
Did you measure between coil pins, or from coil to ground???
 

2informaticos

Administrator
Staff member
Then is pure short there; pretty sure because of fried CPU.

If you want to spend time, lift each coil one side and check where the short remains.
 

Maxibon

Member
G'day 2informaticos!

I've got a similar issue - no water damage, no drop etc.


On a known good board I get a diode reading of .0042 with 120 ohm and 1.6v on these R33 marked coils.


On the board I'm working on I get a diode reading of .160 240 ohm and 0v. Is this also a faulty CPU?

Thanks, Max
 

2informaticos

Administrator
Staff member
0.160 diode mode with 240 ohm readings are compatible.
I don't understand how can you get 120 ohm from 0.0042 diode mode; do you meant 0.042?
Be sure to ALWAYS check diode mode with red probe connected to ground.

Keep in mind, CPU coils readings to ground depends by CPU type.
In the same CPU generation, will be differences from i3 to i7 and between generations too.
None of these values points to bad CPU.
 

Maxibon

Member
Thanks for your reply

The extra 0 in 0.0042 ohm was another mistake lol.

Thanks mate, back to the drawing board ;)
 
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