macbook air 820-3024-B green light no fan spin

[kingskie]

Hello,

I have a problem with macbook air 820-3024-B. there was a liquid damage on U7021 around pin
22 P5VP3V3_VREG3
23 PPBUS_G3H
24 P3V3S5_DRVH
25 P3V3S5_LL
26 P3V3S5_VBST
27 P3V3S5_DRVL

after that i clean and change the U7021 but still no fan spin.

here is the measurement after i change the U7021
22 P5VP3V3_VREG3 -- 3.37V
23 PPBUS_G3H -- 8.4V
24 P3V3S5_DRVH -- 0V
25 P3V3S5_LL -- 0V
26 P3V3S5_VBST -- 0.64V
27 P3V3S5_DRVL -- 0.64V

U7021 is hot even i change for the second and third time. i even changed Q7260 but still the same

can anyone help?

thanks in advanced

[Askic]

Re: macbook air 820-3024-B green light no fan spin

Your PPBUS_G3H is a bit low. When SMC is turned on it will boost PPBUS_G3H voltage from 8.1/8.2 to 8.5/8.6V.

Open schematics and boardview and measure all power rails on page 7/74.

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

Your PPBUS_G3H is a bit low. When SMC is turned on it will boost PPBUS_G3H voltage from 8.1/8.2 to 8.5/8.6V.

Open schematics and boardview and measure all power rails on page 7/74.

here is the measurment

PPBUS_G3H 8.41v
PPBUS_S5_HS_COMPUTING_ISNS 0V
PPDCIN_G3H 17.39V
PP3V42_G3H 3.41V
PPVRTC_G3H 3.41V
PP5V_S5 1.6V
PP5V_SUS 0V
PP5V_S3 0V
PP5V_S0 0V
PP3V3_S5 0V
PP3V3_SUS 0V
PP3V3_S3 0V
PP3V3_S0 0V
PP1V8_S0 0V
PP1V5_S3 0V
PPVCORE_S0_CPU 0V

[Askic]

Re: macbook air 820-3024-B green light no fan spin

PPBUS_S5_HS_COMPUTING_ISNS 0V
PP5V_S5 1.6V

Most probably, you have a short on S5 5V line. Did you check for short circuit on this line (check both in resistance mode and diode mode on your multimeter)?

What is the value of SMC_BC_ACOK?

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

ppbus_s5_hs_computing_isns 0v
pp5v_s5 1.6v

most probably, you have a short on s5 5v line. Did you check for short circuit on this line (check both in resistance mode and diode mode on your multimeter)?

What is the value of smc_bc_acok?

smc_bc_acok 3.2v

resistance
pp5vs5 on c5710 0.393

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

i forgot to tell that the U7201 is hot when i plug the charger. before i thought that U7201 is short but after i changed 3 times it is still hot

[Askic]

Re: macbook air 820-3024-B green light no fan spin

On your place, I would remove the U7201 chip, inspect pads and test them against ground. If the chip is good and it's getting hot, there must be some other component connected to it that is shorted

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

On your place, I would remove the U7201 chip, inspect pads and test them against ground. If the chip is good and it's getting hot, there must be some other component connected to it that is shorted

Here are the measurements to ground after i removed the chip:

PIN 1 = OL
PIN 2 = 0.398
PIN 3 = OL
PIN 4 = 0.445
PIN 5 = 0.467
PIN 6 = OL
PIN 7 = 0.706
PIN 8 = 0.404
PIN 9 = OL
PIN 10 = OL
PIN 11 = 0
PIN 12 = 0.418
PIN 13 = OL
PIN 14 = 0.426
PIN 15 = OL
PIN 16 = OL
PIN 17 = 0.261
PIN 18 = 0.633
PIN 19 = OL
PIN 20 = 0.471
PIN 21 = 0.453
PIN 22 = OL
PIN 23 = 0.429
PIN 24 = 0.261
PIN 25 = OL
PIN 26 = OL
PIN 27 = OL
PIN 28 = 0
PIN 29 = 0.427
PIN 30 = OL
PIN 31 = OL
PIN 32 = 0.410
PIN 33 = 0

[Askic]

Re: macbook air 820-3024-B green light no fan spin

Everything seems OK. I'm now really puzzled too.

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

Everything seems OK. I'm now really puzzled too.

so am i
it is really weird..
any other opinion?

[Askic]

Re: macbook air 820-3024-B green light no fan spin

I'm still convinced that you have a short on a power rail.
So, some switch (MOSFET open) closes and drives power rail line to short.
I would again pay attention to MOSFETS (60/74). Inspect Q7840 for example. On pin 29 of U7201 you should have 5 V, this voltage is later used to create other voltages on the line such as PP5V_S5, P5VSUSFET....

It is possible that something heats up of elements shown on page 60. Try to sense it or use isopropyl alcohol.

[mon2]

Re: macbook air 820-3024-B green light no fan spin

Thanks for the last post with correction.

1) The switching regulator is U7201 (not U7021).

2) What is the PP5V_S3_REG rail voltage? This is generated by this same dual switcher IC.

3) Turn off the power to the board and check the resistance on L7220, pin 1. What is the reading? Maybe a shorted cap on that rail?

4) Perhaps Q7220 & Q7225 should be reviewed / replaced.

5) What is the resistance reading (with power off!) on L7260, pin 2 ?

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

i already watch over that area but no sign of heat comes up...but tommorow i will try to replace that Q7840...i will let you know...thanks a lot bro

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

Thanks for the last post with correction.

1) The switching regulator is U7201 (not U7021).

2) What is the PP5V_S3_REG rail voltage? This is generated by this same dual switcher IC.

3) Turn off the power to the board and check the resistance on L7220, pin 1. What is the reading? Maybe a shorted cap on that rail?

4) Perhaps Q7220 & Q7225 should be reviewed / replaced.

5) What is the resistance reading (with power off!) on L7260, pin 2 ?

thanks for the reply mon2
tommorow i will measure what you asked.

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

Thanks for the last post with correction.

1) The switching regulator is U7201 (not U7021).

2) What is the PP5V_S3_REG rail voltage? This is generated by this same dual switcher IC.

3) Turn off the power to the board and check the resistance on L7220, pin 1. What is the reading? Maybe a shorted cap on that rail?

4) Perhaps Q7220 & Q7225 should be reviewed / replaced.

5) What is the resistance reading (with power off!) on L7260, pin 2 ?

1. yes correct. i type wrongly
2. PP5V_S3_REG is 0V
3. L7220 pi 1 resistance to ground is 0.414
4. already replaced but still the same
5. L7260 pin 2 resistance to ground is 0.271

[mon22]

Re: macbook air 820-3024-B green light no fan spin

Hi. Mon2 here. Was unable to login for the past 2 days. The login procedure appears to be broken, at least for us. To ask for help, you have to login. Yet we cannot log in. Good logic.

2. PP5V_S3_REG is 0V
3. L7220 pi 1 resistance to ground is 0.414
5. L7260 pin 2 resistance to ground is 0.271

Ok, confirm that for (3) & (5) of above, that you are in RESISTANCE mode. Not diode mode.

Black probe on Ground.
Red probe on the requested inductor pins.

Assuming these are indeed resistance (ohms) readings, they are very low in value. This would indicate that you have at least one bad cap on that voltage rail.

This could be the root cause of your problems. After your confirmation of the readings, the logical step will be to inject a voltage that is under the voltage of the rail.

Do you have a voltage injector? Or a good power supply?

We sourced a 30A voltage injector which works fine except for a very dim display. Have used it a few times with very good results.

Interested for you to inject say 2-3 volts on the 5 volt rail and check the current drawn by your power supply. The idea is to never exceed the 5 volts if on a 5 volt rail. Respectively for the 3v3 rail, try 2 volts.

Be sure that you do not see any liquid damage on the PCB - if yes, clean it up with alcohol / ultrasonic cleaner. Personally we find that alcohol cleaning with a q-tip works very well.

Also, we spray the bank of caps we suspect to be bad with alcohol. Then watch for a mist of smoke upon the voltage injection and/or heating of a cap. Method works very well and sometimes you can even smell the bad tantalum as it heats up. Seen the part split in 2 pieces / powder as this process continues.

Once done, the current drawn on this rail will be much lower and respectively, the resistance will be much higher to denote that the short is removed.

Unless someone has better suggestions, this is the approach to consider.

[mon2]

Re: macbook air 820-3024-B green light no fan spin

OMG - finally able to log in again.

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

Hi. Mon2 here. Was unable to login for the past 2 days. The login procedure appears to be broken, at least for us. To ask for help, you have to login. Yet we cannot log in. Good logic.



Ok, confirm that for (3) & (5) of above, that you are in RESISTANCE mode. Not diode mode.

Black probe on Ground.
Red probe on the requested inductor pins.

Assuming these are indeed resistance (ohms) readings, they are very low in value. This would indicate that you have at least one bad cap on that voltage rail.

This could be the root cause of your problems. After your confirmation of the readings, the logical step will be to inject a voltage that is under the voltage of the rail.

Do you have a voltage injector? Or a good power supply?

We sourced a 30A voltage injector which works fine except for a very dim display. Have used it a few times with very good results.

Interested for you to inject say 2-3 volts on the 5 volt rail and check the current drawn by your power supply. The idea is to never exceed the 5 volts if on a 5 volt rail. Respectively for the 3v3 rail, try 2 volts.

Be sure that you do not see any liquid damage on the PCB - if yes, clean it up with alcohol / ultrasonic cleaner. Personally we find that alcohol cleaning with a q-tip works very well.

Also, we spray the bank of caps we suspect to be bad with alcohol. Then watch for a mist of smoke upon the voltage injection and/or heating of a cap. Method works very well and sometimes you can even smell the bad tantalum as it heats up. Seen the part split in 2 pieces / powder as this process continues.

Once done, the current drawn on this rail will be much lower and respectively, the resistance will be much higher to denote that the short is removed.

Unless someone has better suggestions, this is the approach to consider.

hi mon2,

thank for reply.

i do have 10A 30V power supply sunshine brand (china brand)
i think i measure wrongly. here is the measurement as you suggest
3. L7220 pi 1 resistance to ground is 39.6k
5. L7260 pin 2 resistance to ground is 17.04k

[mon2]

Re: macbook air 820-3024-B green light no fan spin

The resistance values look to be ok and do not indicate a shorted capacitor on these voltage rails.

Check that the external pcb traces for this same dual regulator are reaching the actual component.

[kingskie]

Re: macbook air 820-3024-B green light no fan spin

The resistance values look to be ok and do not indicate a shorted capacitor on these voltage rails.

Check that the external pcb traces for this same dual regulator are reaching the actual component.

every traces are ok..
i just measure that PP1V05_S0 is short to ground.. is it ok?