MacBook Air A1466 not powering. Fan spin at very speed.

[kalzabdul]

Hi. I have an A1466, 820-3437-B not powering but there is corrosion around Q8150 and three resistors R8151, R8156, R8154 fell off due to the above.
But when i short SOPGD_C to ground the fan spins very fast but no cpu power
All S0 rails present except PPVCC_S0_CPU.
Below are some other voltages I believe are involved in creating CPU vCore;
All_SYS_PWRGD. • 0.95v
SOPGD_C • 0.98v
CPUVR_FCCM •2.36v
CPUVR_BOOT • 4.85v
CPUVR_PWM. •0.2v
CPU VR_EN. •0v
CPU_VR_READY •0v
PP5V_S0_CPUVR_VDD •5v
PPVIN_S0_CPUVR_VIN. •8.67v
VMON_Q2_BASE •1.8v
VMON_Q3_BASE •0v
VOMN_Q4_BASE •0.7v

[kalzabdul]

Re: MacBook Air A1466 not powering. Fan spin at very speed.

Is there any one with a clue, please it’s urgent

[mon2]

Re: MacBook Air A1466 not powering. Fan spin at very speed.

hi. a lot of information is missing and more details are required.

1) start with page # 49/76 of the pdf schematics.

2) does your magsafe adapter light (green? orange?) stay on when applied to the computer? Are you using an orginal apple adapter? the clones are nasty and can be dangerous to the board. At the very least, if using a clone (not recommended), attach the magsafe adapter FIRST to the computer and then plug it in. We have seen sparks from the connector if docking a hot (clone) adapter. Crap designs from Asia.

3) with the adapter attached, confirm the voltage reading

@ PPDCIN_G3H. Value?

@ D7005, pin #3. Value ?

@ L7905, pin # 2. Value ? This rail must be stable @ +3v42 to power the critical components of the logic board.

If this rail is not at this value, power down - remove battery / adapter - then use a meter to check the resistance to ground on L7905, pin # 2. Value ?

@ PPBUS_G3H = F7140, pin # 2. Value ? If F7140 is zero, check pin # 1 of F7140.

If this rail is not at this value, power down - remove battery / adapter - then use a meter to check the resistance to ground on F7140, pin # 2. Value ?

In general, checking the resistance to ground of each grey coil is a good idea to quickly review if you are facing a bad capacitor on the logic board. We have fixed at least 3 A1466 units using this approach. A low resistance value is a reading that is < 10 ohms - then we can investigate further.

[piernov]

Re: MacBook Air A1466 not powering. Fan spin at very speed.

VMON_Q3_BASE •0v

Missing/bad PP3V3_S0, R8154 or R8158.