a1706 820-00239-A boots up just sometimes

[Harryrepair]

Hello all,

i have got a Macbook a1706 which boots up just sometimes.

PPBus_G3h 13.06V
PPVCCSA_S0_CPU 1.1V
CPUVR_PGOOD 3V

Vcore 0V

All other Power Rails seem to be OK.

Sounds to me like a bad solder connection.

Any hint where and how to search ?
I thought on reballing U7100 maybe.

Kind Regards

[SMDFlea]

Re: a1706 820-00239-A boots up just sometimes

Whats the history of it,any liquid damage etc .Have you gone through the list of power rails and checked everything

[Harryrepair]

Re: a1706 820-00239-A boots up just sometimes

I measured all Power Lines.
Attached my results.

[piernov]

Re: a1706 820-00239-A boots up just sometimes

Cpu_vr_en_r?

[Harryrepair]

Re: a1706 820-00239-A boots up just sometimes

Cpu_vr_en_r 3.24 v


On charger:
20.3 V
consumption 0.15a

[piernov]

Re: a1706 820-00239-A boots up just sometimes

Try to flash the BIOS.

[Harryrepair]

Re: a1706 820-00239-A boots up just sometimes

How do i do that?
This is new to me.