Hi all , I am working on a Apple MacBook Air A1466 820-00165-A logic board. The problem was no back light & all was working fine. I replaced the Backlight chip but still no display & now it does not even turn on. I replaced with a known good back light chip assuming the soldered chip was shorted. But still no luck. Now I measure voltage rails. 3.3V is perfect but 5V Rail Pulses (on & off). TPS51980A, 5V ENABLE pin 4 P5VS4RS3 EN R also fluctuates on & off. 5V comes & then shut off again. This happened continously. I checked for any short to ground, but none. When I check for where this signal is genrated, PM_SLP_S4_L also go on & off. Any help would be greatly appreciated. Thanks
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Re: MacBook Air A1466 820-00165-A 5V Rail Pulses (on & off)
Hi.
Review this excellent website / webpage:
https://www.it-tech.com.au/mac-q-a/pm-slp-s4-l-timing/ -
Re: MacBook Air A1466 820-00165-A 5V Rail Pulses (on & off)
And...
https://logi.wiki/index.php/820-00165_PulsingComment
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Re: MacBook Air A1466 820-00165-A 5V Rail Pulses (on & off)
Thanks you so much "mon2" for the knowledge above.. I will surely read tomorrow & let you know the out come.Comment
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Re: MacBook Air A1466 820-00165-A 5V Rail Pulses (on & off)
If you are getting pulsing of rails up to CPU Vcore, then that is usually U6100 related. Make sure none of the termination resistors are knocked off or corroded.
If the display is detected, then you should see 8.6V on L7701 (means backlight enable is on and F7700 is ok), then troubleshoot U7701 from there (should have 25V on C7797/C7799). Don't forget to give J8300 a good clean too with IPA. I had one the other day that wouldn't detect the display until cleaning it, despite it looking perfect.Last edited by reformatt; 01-05-2022, 12:09 AM.Comment
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Re: MacBook Air A1466 820-00165-A 5V Rail Pulses (on & off)
Thanks for the reply "reformatt"... Just for fun sake I re-programmed U6100, but still the same. As of now the Enable pin of 5V of U7501 is also pulsing. Yesterday I went through the power rails once again & observed that PP3V3 S5 is perfect but PP3V3 S4 is also pulsing. 3.3v comes & then off & on, though accordingly this rail should be AWON. I am still checking, it a challenge & have to repair it.Comment
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Re: MacBook Air A1466 820-00165-A 5V Rail Pulses (on & off)
The only rails that are always on are PP3V42_G3H, PPBUS_G3H and the S5 rails. So your statement that a S4 rail is always on is incorrect. You need to check all rails up to CPU Vcore to see if they are pulsing. Also check if you have activity on pin 1 of C6100 with a scope.Comment
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hi, i also have the same (P5V_S4RS3) MacBook Air A1466 820-00165-A 5V Rail Pulses (on & off) The strange thing is when I kept machine for 1 day and connect the power It powers on with Chime and booots half way with Apple logo and stuck. at that time when I power of and try power up Fan spins for few seconds and goes off with no P5V_S4RS3 and also the P5V_S4RS3 EN pulses on and off with 3,24 V. Plezzz doesn any one can help me
08-26-2024, 09:54 AM -
I received a 2013 Macbook Air A1466 820-3437-B motherboard with serial number C02L6GQ9FSV8 that came in WITHOUT a bios chip. I got a new bios chip and reprogrammed it. Macbook now powers on but doesn't boot the SSD. I've flashed a ton of bios but still same problem. Windows installation works with this Macbook but never a mac installation. Unfortunately, since I didn't receive this macbook with a bios chip, I don't have the original bios. What can I do now?... -
Hi, I'm Daniel, and I'm new to the world of repairing motherboards.
I would like to create a table, or more likely a guideline about the voltage rails and their possible resistance rail.
I know that the motherboard design has a very big depend on the rail's resistance, but I would like to know what is the smallest value for a rail that can be acceptable. For example, I heard that some new gaming motherboards can have 0,5 Ohm resistance on the GPU rail, but on an older type, it could be a sign of a shorted GPU rail.
So, I generated a table with AI so I can... -
Hello all,
Working on my wife's 13' Macbook air. It's been in a box since she upgraded but I figured it could be good practice.
Details:
Macbook 13' A1466
Board (820-3209-A)
Battery OEM 7.3v 50Wh 6700 mAh (020-7379-A)
Pictures below of Boardview and schematic...
I don't know how to test the voltage on a MacBook battery. I just assumed it had an enable pin but the best I could read was 300 something mV poking around the battery connector.
It's an older model and it is very likely that battery has become... -
Hi all,
i got a A1466 with serious water damage. I was able to clean the whole board and only found a fuse with a coroded trace. Cleaning and resoldering did the job and the macbook started normal but after some time the screen began "flashing" like turning on and off while the Macbook was still running. I checked the board again but was not able to find the problem until now.
Any ideas where to look?...
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