MacBook Air Early 2015 13" No Power

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

after further testing on the board with it powered on to monitor the voltages ive noticed that

u2800 is getting hot.

is that normal ??

[mon2]

Re: MacBook Air Early 2015 13" No Power

So 0 is the expected measurement when checking a PCB trace.

The fact that you are measuring a boosted voltage for the backlight is a very positive result. That is, this IC is taking in a low voltage from the DC adapter or battery pack and boosting it up to drive the backlight LED array in your display.

However, for some reason, this boosted voltage is then being possibly disabled. Confirm the ENable signal for this IC.

This signal is responsible to turn the backlight ON / OFF. What we want to now learn is if this signal remains ON or does it turn OFF by the demand of the other logic on this board.

Can you confirm the 820-xxxx board # for this unit with the backlight issue?

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

820-3437-B is the board number for this one

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

hi for backlight enable its showing 3.3v and stays there.

[mon2]

Re: MacBook Air Early 2015 13" No Power

After the unit is powered on, using a flashlight / torch on the front face / edges or even the backside (behind the apple logo) -> can you see the usual LCD graphics ?

That is, the display is working but only the backlight is failed ?

Does the keyboard keycaps key LED toggle ok ?

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

ok ive just retested it with the battery connected and im now getting backlight and 24v

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

but if I turn it off and back on then there is no backlight.

[mon2]

Re: MacBook Air Early 2015 13" No Power

Do you see the graphics ok when the backlight is ON ? When the backlight is OFF, is the ENable pin high or low on the voltage ? 3v3 is a good high and the backlight should be on.

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

yeah its ok when on now and showing the login screen,

also the enable pin is showing 3v I just rebooted it again while the battery is connected and it loaded up with the backlight on.

and the chip u2800 is also not heating up now ???

[mon2]

Re: MacBook Air Early 2015 13" No Power

I do know that some macbooks demand the use of a charged up battery to allow it to boot. Not sure about this one but it may be the same model as what we had in the building about a month ago - we wasted too much time on that logic board and it worked fine with a fresh known good battery. Let me check my notes..

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

thanks I appreciate all the help.

im running the AHT. now to see what it says.

id still like to fix the original board as I think the one in there now may be a 2013/2014 board but its working..

[mon2]

Re: MacBook Air Early 2015 13" No Power

The one we had was an A1398. The CPU resistance to ground was 1 ohms !! Thought for sure it was fried. The unit worked fine after a fresh battery was installed. The keyboard has 90,000 rivets keeping it in place. As that would have taken a week to replace, the client declined to have the older unit fixed from some sugary drink spill.

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

The one we had was an A1398. The CPU resistance to ground was 1 ohms !! Thought for sure it was fried. The unit worked fine after a fresh battery was installed. The keyboard has 90,000 rivets keeping it in place. As that would have taken a week to replace, the client declined to have the older unit fixed from some sugary drink spill.

yeah I know what you mean

this one had a sugary drink spill but I did ultrasonic board clean it.

and then used IPA

and now its working oddly and ive done nothing to it..

so im wondering how long now it may last lol

but that's a guess on anyones part.

but any other things I can check on the 2015 board ??

[mon2]

Re: MacBook Air Early 2015 13" No Power

I have mixed reviews of using ultrasonic cleaners - we have 2 of them and found that liquid damage causes the components to become like lepers. Just the slightest nudge and the parts fall off of the PCB pads. These days we use IPA at selective sites and proceed with extreme caution to see if the board can be salvaged. Seen too many times, where the parts are at the bottom of our ultrasonic cleaner tank which make it more fun to repair.

Will review the earlier board comments in a bit.

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

now see that's a valid point.

I didn't think of it helping parts fall off but your right I use iPA for everything else.


thank you so much for all the help so far I can't say thank you enough.

[jasonr2000]

Re: MacBook Air Early 2015 13" No Power

I have mixed reviews of using ultrasonic cleaners - we have 2 of them and found that liquid damage causes the components to become like lepers. Just the slightest nudge and the parts fall off of the PCB pads. These days we use IPA at selective sites and proceed with extreme caution to see if the board can be salvaged. Seen too many times, where the parts are at the bottom of our ultrasonic cleaner tank which make it more fun to repair.

Will review the earlier board comments in a bit.

hi again

im sorry to ask but did you review the previous comments about the original logic board issue ??