Macbook Air A1466 - 820-00165 Display flickering

miranda_ss

New member
Hi guys, first post here.

This A1466 - 820-00165 display starts flickering and blinking a few moments before the end of system bar startup running. When the login screen appears, I almost can't see. This is not happening with the external monitor. Tried a new display and the same happens. If I log in and activate the Colors filter, everything works fine again, but the screen gets dark if I don't touch the mouse or keyboard after a few seconds.

After a few days checking this board, I noticed that this flickers starts when vcore drops on both inductors L7310 / L7320. Any Idea?
 

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

Check SMC_LID level when problem appers.
There may be corrosion between U7701 balls; need to replace it.
Check all traces and adjacent resisors.

Any history available?
 

miranda_ss

New member
Thanks!

SMC_LID is 3.3v stable. Checked on R5171.
U7701 replaced, nothing changed.

No liquid damage, board is nice and clean.
 

miranda_ss

New member
The backlight is working good every time, no instability. That was my first guess too.
The U7200 is where things are strange to me. CPUVR_FCCM, CPUVR_PWM and CPUVR_PWM1 are stable until flickering starts.
 

miranda_ss

New member
I received today another 820-00165 today for cleaning and will check differences between boards. The U7200 suspect I had is not valid. This one is unstable too, so that's not the problem, it is the normal operation.
 

2informaticos

Administrator
Staff member
Do PRAM reset 2-3 times, also SMC reset.
Just in case, disconnect internal SSD and test with known good USB macOS.
 

miranda_ss

New member
Made PRAM reset 5 times, also SMC, no news
Tested with known good USB macOS, no news
Tryed to reinstall on a new SSD, impossible. Black screen or image flickering after apple logo.
 

2informaticos

Administrator
Staff member
Be sure to use original Magsafe 2 charger.
Problem appears w/ and w/o known good battery connected?
Also test starting in safe mode and SMC bypass.
 

miranda_ss

New member
- Used 2 different known good original magsafe 2.
- Yes, it appears w/ and w/o known good battery.
- No news in SMC bypass or safe mode.

Why that problem "go away" temporally when I enable color filter? What really change on screen?

This machine is really testing my patience!
 

2informaticos

Administrator
Staff member
Check all resistors and traces around U7701.
Be sure XW7720 is good.

You can try changing video connector; at least clean it.

If external video is OK, shouldn't be iGPU related.
 
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