820-01958 chime, blank display and restart

[kingskie]

Hi all,

i have macbook air A2179 820-01958 that some water damage around:
- CC714 and CC715 (PP5V_G3S)
- C6523 (PPVOUT_S0_KBDBKLT_R)
- F3000 (PPDCIN_G3H and PPHV_INT_X_G3H)

after clean all those components. i tried to turn it on bust have blank display and always restart (based on chimes)

here are the measurements:

- PPBUS_G3H = 12.58V
- PPBUS_HS_CPU = 12.58V
- PPDCIN_G3H = 19.98V
- PP5V_G3S = 5V
- PP5V_S5_LDO = 5V
- PP3V3_G3H_RTC = 3.271V
- PP3V3_G3H = 3.271V
- PP1V8_G3S = 1.795V
- PPVCC_S0_CPU = 1.6V
- PP1V1_S3 = 1.095V
- PP0V6_S3 = 1.01V

N.B CPU is very hot

what could be wrong?
any help would be appreciated.

thanks before

[mon2]

Re: 820-01958 chime, blank display and restart

hi.

1) do not power on as PP0V6_S3 = 1.01V is incorrect and could cause damage. This rail should be 0V6.

2) See attached. Inspect the parts in the red box. Each value should be correct to properly allow for the buck regulator to regulate to 0V6. Based on the measured value, the FB resistor(s) are not the proper value.

[kingskie]

Re: 820-01958 chime, blank display and restart

hi.

1) do not power on as PP0V6_S3 = 1.01V is incorrect and could cause damage. This rail should be 0V6.

2) See attached. Inspect the parts in the red box. Each value should be correct to properly allow for the buck regulator to regulate to 0V6. Based on the measured value, the FB resistor(s) are not the proper value.

i checked value for:
R8150 9.8ohm
R8151 90.8ohm
R8152 2K ohm

so i changed R8152 but the value still 2K ohm...if P0V6_S3_FB is shorted that means the value for R8151 shouldnt be normal right?

[kingskie]

Re: 820-01958 chime, blank display and restart

i just found out that PP1V1_S3 is shorted to ground

[M4n0l0307]

Re: 820-01958 chime, blank display and restart

hi.

1) do not power on as PP0V6_S3 = 1.01V is incorrect and could cause damage. This rail should be 0V6.

2) See attached. Inspect the parts in the red box. Each value should be correct to properly allow for the buck regulator to regulate to 0V6. Based on the measured value, the FB resistor(s) are not the proper value.

Thank you friend !