MacBook Air 820-00165 shutting down when trying to boot

[Simplebeans]

I wondered if anyone could help me with the repair I am currently undertaking, I have a MacBook Air - A1466 with logic board 820-00165. The issue I am having is the MacBook Air switches on when pressing the power button and powers up to the apple logo and chime sound, then the loading bar under the apple logo reaches about 3/4 of the way and then the MacBook air just switches off. This happens the same every time I try and boot the machine.

Any ideas what could be causing this? I had a look on the logic board and everything seems fine, the CPU heatsink seemed to be getting pretty hot during boot up, so I replaced the thermal paste but its still the same heat and that has not solved this issue. I have replaced the SSD with a new one but that has not made any difference either. Any ideas?

[mon2]

Re: MacBook Air 820-00165 shutting down when trying to boot

Have you tried a SMC reset ?

https://discussions.apple.com/docs/D...the%20computer.

[reformatt]

Re: MacBook Air 820-00165 shutting down when trying to boot

Eliminate the simple stuff first. Try a genuine magsafe charger, PRAM reset, boot to safe mode and also try SMC bypass to narrow down the problem. You could try removing the SSD and booting from a USB MAC OS installer and see the result.

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

Thanks to both of you so far and I am using a geniune magsafe charger. So this is what i have tried so far:

SMC reset: made no difference
PRAM reset: when pressing the keys the macbook air does not load far enough before it switces off for the PRAM reset to work
Safe Mode: again whe pressing the key the macbook air does not load far enough before it switces off for the safe mode to work
SMC bypass: when i tried this the fan spins very loud and it gets to the apple logo with the progress bar but again switches off.

I have not tried the booting from the USB yet as i have had to order another USB drive the one I have the size is not enough. What MAC OS do i need to download because i am not sure for this, i will be creating this bootable installer from my Windows 10 machine.

Any other ideas?

[mon2]

Re: MacBook Air 820-00165 shutting down when trying to boot

Power down. Remove the SSD. Then power up again without the SSD. After a while the LCD screen should show a flashing '?' mark graphic which means the SSD could not be found.

Are you able to leave this logic board up and running to see this flashing question mark?

If the hardware is stable, the logic board should remain on this screen till you decide to turn it off.

Confirm that you can see this graphic and leave it running for 15+ minutes to validate that other hardware is not at fault on this unit.

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

Yes when I used to try and boot without the SSD previously (1 week ago, when i was waiting for my new SSD to be delivered) you used to hea the chime and then it did used to display the the flashing ? mark folder graphic but then it would just switch off.

I have just tried it again now after having my new SSD instal for a few days, I removed SSD but now you just hear the chimes, you can see the backlight come on and then switches off with nothing displaying on the screen.

I suspect the Macbook Air is still swithching off at the same time maurement but now for some reason it doent get to the ? mark folder graphic in time.

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

Sorry double post same as above.

[mon2]

Re: MacBook Air 820-00165 shutting down when trying to boot

When you lose the backlight & display - does the fan turn OFF ?

Respectively, after this event, can you use a flashlight (cellphone) from the backside of the display panel to view the same graphics ?

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

When you lose the backlight & display - does the fan turn OFF ?

Respectively, after this event, can you use a flashlight (cellphone) from the backside of the display panel to view the same graphics ?

Yes the fan, blacklight and display all power off at the same time. Shining my cellphone torch on the macbook air display after the power off displays no graphics on the screen.

[mon2]

Re: MacBook Air 820-00165 shutting down when trying to boot

Consider to check for possible bad caps.

Meter in resistance mode (2k). Remove all power.

Check the resistance to ground of each coil. Looking for any really low resistance on the coil which will denote a possible faulty cap on that rail. Believe we have some of these logic boards in the building so if in a pinch, we can cross compare values.

When you lose power - what color is the LED on the magsafe power adapter ?

After you lose power, what are the voltage readings for:

a) PPBUS_G3H

b) PPVIN_G3H_P3V42G3H

c) PP3V42_G3H

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

Consider to check for possible bad caps.

Meter in resistance mode (2k). Remove all power.

Check the resistance to ground of each coil. Looking for any really low resistance on the coil which will denote a possible faulty cap on that rail. Believe we have some of these logic boards in the building so if in a pinch, we can cross compare values.

When you lose power - what color is the LED on the magsafe power adapter ?

After you lose power, what are the voltage readings for:

a) PPBUS_G3H

b) PPVIN_G3H_P3V42G3H

c) PP3V42_G3H

Here are the voltage readings for you mon2. Meter in voltage mode (20V) and this is with both the battery and magsafe charger connected at the same time, bearing in mind after the power off happened i waited about 5 minutes before testing the voltages, also see the screenshot (https://drive.google.com/file/d/1Gb4...ew?usp=sharing) for the testing points that i used on the logic board to measure these voltages, this is the first time i am working on a macbook air myself so i hope this is all correct:

a) PPBUS_G3H - tested L7130 coil on both sides - reading 8.59V
b) PPVIN_G3H_P3V42G3H - tested on U7090 chip at PIN 6 - reading 14.56V
c) PP3V42_G3H - tested on L7095 on both sides - reading 3.43V

It was interesting you mentioned about the colour of the magsafe LED on power down, when the battery is not fully charged when i plug the magsafe charger in the LED goes from green to orange colour and remains an orange colour on power down as well, however what was strange was i unplugged the battery from the logic board and again plugged in the magsafe charger and the LED still went from green to orange colour and also was an orange colour on power down. I thought the LED is supposed to only go orange when it has a battery and is taking some charge?

Now the battery is fully charged the MagSafe LED just stays as a green colour when plugged in and on the power down.

Mon2 for the resistance to ground testing is there any perticular coils you want me to check or all the obvious ones I can see on the logic board?

Thanks for all your help so far.

[reformatt]

Re: MacBook Air 820-00165 shutting down when trying to boot

Retry the PRAM reset. Proper sequence is you hear the chime, the screen flashes, and you hear the chime again.

Shut downs on 820-00165 boards that have no immediately visible corrosion are very difficult to track down (especially Apple FRU boards which usually end up in the donor bin). To see an Apple logo, you've gotten to the end of the power sequence and read the EFI. It may be an overcurrent situation and/or faulty feedback from a current sense resistor (see pg 54). My approach would be to examine everything under a microscope very carefully, especially around the edges of the boards. Main things to look for on A1466 boards are corroded test points, crap in and under the SMC/U6100/U8005, and crap on the joints of any of the QFN buck conveter IC's. The hardest things to spot are when an insect has taken a dump on the end of a passive component. This type of corrosion is very easy to miss.

You may also want to check the ISL6259 resistors R7121/7122/7151/7152 for current sense and around the SMC for any signs of dried up liquid spillage.

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

Retry the PRAM reset. Proper sequence is you hear the chime, the screen flashes, and you hear the chime again.

Shut downs on 820-00165 boards that have no immediately visible corrosion are very difficult to track down (especially Apple FRU boards which usually end up in the donor bin). To see an Apple logo, you've gotten to the end of the power sequence and read the EFI. It may be an overcurrent situation and/or faulty feedback from a current sense resistor (see pg 54). My approach would be to examine everything under a microscope very carefully, especially around the edges of the boards. Main things to look for on A1466 boards are corroded test points, crap in and under the SMC/U6100/U8005, and crap on the joints of any of the QFN buck conveter IC's. The hardest things to spot are when an insect has taken a dump on the end of a passive component. This type of corrosion is very easy to miss.

You may also want to check the ISL6259 resistors R7121/7122/7151/7152 for current sense and around the SMC for any signs of dried up liquid spillage.

Hi reformatt i tried the PRAM reset again and this time the macbook air makes the first chime sound and then it shows a blank backlit screen with no apple logo and then stays on the blank screen until it switches off again (never reaches the second chime sound). It does not seem to be able to fully complete the reset because of the power down issue.

I completed a check of the board under the microscope and did not find anything that was a concern. The only thing i found was very small green dot (could be corrosion) next to the ISL6259 power IC, i have cleaned this off with some isopropyl alcohol and a toothbrush. Please see this screenshot (https://drive.google.com/file/d/1_tu...ew?usp=sharing), i have circled where this green dot was and the size of the circle is close enough to the actual size of it. Apart from this the logic board is clean.

I tested the voltages as well at the coils, meter in voltage mode (20V) and measurements taken on both sides of the coils and this was when the macbook air was switched on (no magsafe charger plugged in, running on batter only) and attempting to power up:

L7701 - 7.60V - 7.90V fluctuating voltage (measured when the backlight switches on)
L3095 - 0V
L7520 - 5.10V
L7560 - 3.33V
L7430 - 1.20V
L7630 - 1.05V
L7310 - 1.80V
L7320 - 1.80V

I also tested the ISL6259 resistors, meter in resistance mode (200Ω), this is the readings i got:

R7121 - 10.5 omhs
R7122 - 10.3 omhs
R7151 - 2.6 omhs
R7152 - 0.04 omhs

[mon2]

Re: MacBook Air 820-00165 shutting down when trying to boot

L3095 @ 0v is not normal.

See here for the power rails required for the 820-00165:

https://www.logi.wiki/index.php/Power_Rail_List

L7701 is too low for the backlight voltage to be on.

1) Check the LCD connector for possible corrosion. Use alcohol and q-tip to wipe and clean the contacts.

2) Meter in resistance mode (2k is ok).

Red meter lead on PPHV_S0SW_LCDBKLT; Black meter lead to ground.

What is the resistance ?

3) U7701 is the backlight IC. It operates over I2C (SMBUS) interface. Respectively, the SMBUS interface must be present and working to configure the backlight voltage setting.

Meter in DC volts scale (20V is ok).

With the battery on, what is the voltage reading for:

SMBUS_PCH_CLK
SMBUS_PCH_DATA

You can measure these at the 0 ohm resistors in series with each line (R7753 & R7757).

4) Post the voltages for the ENABLE pin of U7701.

a) Voltage @ PPVIN_S0SW_LCDBKLT ?

b) Voltage @ BKL_EN ? You can measure this voltage at the junction of R7731 & R7715.

We need to be sure that the BKL_EN voltage is high enough to enable the backlight.

If the above conditions are met and the resistance is not too low on the backlight rail then it is possible that U7701 is defective and needs to be replaced. This is a common failure and we have replaced the same a number of times. The part is available offshore but best to source from Arrow or TI.com directly to get the real deal.

5) See attached - post the voltage readings for 1-5 test points.

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

Hi mon2 does the L7701 coil readings depend on whether the macbook air has the magsafe charger plugged in or not? The voltage readings i provided in my last post was when there is no magsafe charger plugged in, running on the battery only. I just plugged in the magsafe charger with the battery plugged in also and measured and now i get the following readings:

L7701 - 8.55 - 8.57V fluctuating.

I also get different readings for the L7130 coil depending on if i have the magsafe charger plugged in or not, i have taken these readings as well to show the differences in both scenarios:

Without the magsafe charger plugged in just running on the battery:
L7130 - 8.37V - macbook switched off
L7130 - 7.90 - 8.15V fluctuating with macbook switched on and trying to boot

Magsafe charger plugged in with the battery plugged in also:
L7130 - 8.59V macbook switched off
L7130 - 8.59 - 8.62V fluctuating with macbook switched on and trying to boot

The L3095 coil is that is part of the TBT 15V Boost Regulator and will that only will show any voltage reading when there is a thunderbolt cable plugged in? (I do not have a thunderbolt cable plugged in) Correct me if i am wrong i am still learning.

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

Hi mon2 I checked the resistance to ground for each of the coils, the battery was disconnected and no magsafe charger plugged in, these are the readings I got below:

Multi meter in resistance mode (2KΩ) black probe on ground point and red probe to coils:
L7310 - .014KΩ
L7320 - .014KΩ
L7360 - .296KΩ
L7430 – 1.3KΩ
L7560 – 1.9KΩ

Multi meter in resistance mode (200KΩ) black probe on ground point and red probe to coils:
L7520 – 43KΩ
L7130 - 54KΩ
L3095 - 74KΩ
L7701 – 59KΩ

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

Sorry the coil in my last post was labelled incorrectly, it is not 'L7360', I have corrected it below:

L7630 - .296KΩ

[bluestone]

Re: MacBook Air 820-00165 shutting down when trying to boot

Check for short on C5125, if not could be bad sensors

[ACS-Repair]

Re: MacBook Air 820-00165 shutting down when trying to boot

I'm working on a similar problem. Try this:
Flip the computer over and remove the bottom if required. Locate C1060 and heat the area with an SMD station at 200c for 10-15 seconds, enough to heat the cap to be fairly warm. Quickly flip the computer over and start it up. Report back the results.

[Simplebeans]

Re: MacBook Air 820-00165 shutting down when trying to boot

I'm working on a similar problem. Try this:
Flip the computer over and remove the bottom if required. Locate C1060 and heat the area with an SMD station at 200c for 10-15 seconds, enough to heat the cap to be fairly warm. Quickly flip the computer over and start it up. Report back the results.

Thanks I tried this but its still the same result and the macbook air switches off. What's the purpose of this then and any other ideas?