Macbook 820-00165 No Image , No Backlight

[Instafixx]

Hello Everyone, Namaste from India,
We have a Macbook Air A1466 820-00165 that came in for repair for No Backlight. We first replaced the screen to check but the problem was from the motherboard it seemed.
We treid repalcing the U7701 but didnt help. The image is also lost now. We put back the old U7701 for now.

Current Findings:
L7701 - With Screen 0 Voltages with Screen Connected and 8.5V without Screen.
C7710 - No Voltage.

P.S There is no chime. The fans are spinning at a high speed and the board is heating.

Any help would be highly appreciated.

[mon2]

Re: Macbook 820-00165 No Image , No Backlight

https://youtu.be/_NR-jnBD7_4

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

https://youtu.be/_NR-jnBD7_4

Hello Mon2,

Thank you for the prompt reply, but i amgetting proper value in the resistors showed in this video. R1540 / R1541 /R1542 /R1543.

[mon2]

Re: Macbook 820-00165 No Image , No Backlight

Review carefully the lcd connector to be sure there is no short / contact damage.

Is the tested lcd compatible and known good?

Do you see the keyboard caps key light toggle? This confirms that the os has booted ok and you are at the login screen. If yes, perform a SMC and PRAM reset.

Are you booting with a good ssd with a good OS? Remove the SSD and keyboard to check if the fan spin is improved?

Remove all power and the lcd screen. Meter in resistance mode. Measure the resistance to ground of the inductor L7701.

What is the resistance?

Next, attach the display but do not apply any power and repeat the same test.

What is the resistance with the lcd connected?

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

Hey ! Thanks for guiding.

Findings
1 - No Short or Connectivity Issue in the LCD Connector
2 - The LCD is compatible and good.
3 - The Macbook is not booting as i cannot toggle the caps button. Moreover the fan only starts to spin when put on charge.
4 - Removed Keyboard and SSD but the fan speed is the same.
5 - Resistance is 5.032 without Power and Display
6- Resistance is 5.032 with LCD and Without Power

[mon2]

Re: Macbook 820-00165 No Image , No Backlight

What is the meter scale used for the resistance scale ?

Is the reading ~5 k ohms ?

You are unable to see any graphics even with a flashlight / phone torch mode on the display ?

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

Hey!
We have set the meter scale to this. I hope this is right to test the resistance. PFA below !

We are unable to see any graphics with a flashlight also. We were able to see the apple logo previously before we had replaced the chip.

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

Update ! Just tried putting the motherboard in a different dead macbook and tried switching on. The fan runs normally but then switches off in 10 seconds and the same thing keeps on happening as if its rebooting or trying to boot.

[mon2]

Re: Macbook 820-00165 No Image , No Backlight

Ok. The meter is not in resistance mode.

When checking resistance -> start with the WHITE text 200 scale (lowest on your meter) -> check the resistance.

If you see '1', this means the meter is trying to tell you the resistance is higher than 200 ohms. So switch to the next higher resistance scale till you have a reading.

On your update -> the board is now power cycling ? That is a good sign.

Do you see any graphics on the display or is this power cycling without the LCD connected?

It is very possible that the backlight IC is not soldered properly. The suggestion for soldering such parts is to flux the part -> good heat BUT low air pressure. Be patient till the balls melt and test this with tweezers across two (2) edges.

With a gentle push, the IC should move but do not push to hard. Once the solder is in liquid mode, the IC can be pushed slightly and it will bounce back, naturally. This corrects any solder ball shorts under the IC.

Learned this from Louis' videos = 'make the IC dance!'. Again, do not push too hard.

This is recommended if you are in doubt of the soldering of this WLCSP package backlight device.

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

Hey! Many thanks for showing me how to check resistance. The resistance with and without LCD is 01.3 to 01.4.

There was no graphics at all. Will reball the IC as you said and let you know.

[mon2]

Re: Macbook 820-00165 No Image , No Backlight

See here about the logic board pulsing:

https://logi.wiki/index.php/820-00165_Pulsing



Pulsing every five seconds

Had a case with all voltages pulsing every 5 seconds. In my case it was failed R1275

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

Hey ! There is some weird issue with this board. Its not pulsing now. Its gone back to high speed fan spinning continuosly. i think its now time to say goodbye to it. (

[mon2]

Re: Macbook 820-00165 No Image , No Backlight

Up to you..

1) with the high fan spin, does the logic board boot ? Do you see the CAPS LED turn on / off with a press after a while ?

2) the high fan spin can be a sensor fault and/or PRAM values need to be reset.

3) Using an external dongle, you can test if the video works on an external monitor.

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

1)The board does not boot with high fan speed. No Caps Button LED.
2)Have done PRAM reset. Which sensor can be faulty.
3) Will check about external monitor and let you know in a bit.

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

Up to you..

1) with the high fan spin, does the logic board boot ? Do you see the CAPS LED turn on / off with a press after a while ?

2) the high fan spin can be a sensor fault and/or PRAM values need to be reset.

3) Using an external dongle, you can test if the video works on an external monitor.

Hey,
Luckily got another Macbook Air (Same Version) fully working condition. When we plugged in the old motherboard in this macbook - We get orange charging light but nothing on the display. No fan movement either.

[mon2]

Re: Macbook 820-00165 No Image , No Backlight

Measure and post the following voltages:

3V3_S5
3V3_SUS
PM_BATLOW_L
PM_DSW_PWRGD
PCH_DSWVRMEN
PM_RSMRST_L
PM_PWRBTN_L

[Instafixx]

Re: Macbook 820-00165 No Image , No Backlight

Hey! Sorry for the delayed response. Was down with Covid and the cleint was giving no more time hence had to return. Thanks for all the help anyway.