00165-a

Anterweb

Member
Having a right shit night of it tonight!

Have this mac air, it was a trade in from a customer had a damaged screen, I replaced the screen cleaned it installed monterey and had it up for sale for weeks. Got a call from someone today that wanted it, so took it from the shelf to give it a clean and get it ready. Won't fkin turn on!

It worked perfectly before I even used it for browsing the net for a couple of weeks.

I get fan spin and both green and orange light on charger, no bong no display, nothing on external display and I can't seem to get any USB activity.
Voltages all look good so went over the usual suspects and find R7122 /R7121 are bad, I've replaced these but still the same symptoms, I got fed up with it at one stage today and walked off leaving it with plugged in, came back 2 hours later and it was at a login screen! Yey I shout. Shut it down clean it, now same thing again it just won't boot, fan spin, lights on magsafe no display,

Any ideas?
 

Anterweb

Member
Do you get VCORE and PLT_RESET_L? = No
ALL_SYS_PWRGD. = No again.,

With the board on the bench to test voltages I get green then orange light on charger but no fan spin., But if I put the board back in the case and connect the battery I do get fan spin! and all main power rails seem to be there, I can read good voltages on all coils but no boing and no screen,

Shouldn't this board auto turn on with battery disconnected?
 
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2informaticos

Administrator
Staff member
Yeah, it should.
But you didn't specify which voltages appear on the MLB alone on the desk.
What about 3V3_S5/SUS at least?
Did you test with original 45/60W Magsafe 2 charger?
 

Anterweb

Member
Connecting an oldf keyboard to trigger SMC_ONOFF_L,. I do get drop pulse on PM_PWRBTN_L and fan starts to spin

PM_BATLOW_L is steady is a steady 3.30v
 

2informaticos

Administrator
Staff member
You don't need keyboard to trigger SMC_ONOFF_L; didn't see R5115/16 pads?

If fan starts to spin, more voltages should be present; check on the big coils.
Is good to use an USB tester.
 

Anterweb

Member
I Normally use R5115/16 after U showed me these but sometimes when trying to measure you have to be a bit of an octopus! having a few old keyboards with working power button make it a bit easier sometimes,

Still seems to power on, Just no bong no display,.
Measured coils


L2920 = 1.0V
L7750 =5.1V
L3130 = 8.33V
L3095 =1.4 mV??
L7701 =3.6 mV ??
L7520 = 5.08V
L7560 = 3.16V
L7430 = 1.214V
L7630 =1.063V
L7320 = 1.783V
L7310 = 1.785V

Do you use the one Harold sells? been thinking of getting this? any other of his tools worth me getting as it seems daft just ordering the USB tester alone?
 
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2informaticos

Administrator
Staff member
I have Harald USB tester and I use it daily.

As you now get VCORE, let us know about ALL_SYS_PWRGD and PLT_RESET_L.

BTW, soldering a small push button on R5115/16 pads, is the best way to test the board alone on the desk; use 5-10cm wires for connection.
 
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Anterweb

Member
Going to order from Harold today!

And get a couple of push buttons., thanks

ALL_SYS_PWRGD and PLT_RESET_L both at 3.30v with fan spinning.
 

2informaticos

Administrator
Staff member
Check all SPI Bus Series Termination resistors and their traces.
Be sure J6100 is clean.
Try known good BIOS.
Also check all voltages from pages 11 & 58.
 

Anterweb

Member
That should keep me busy :ROFLMAO:

II tried to try a fresh bios but I just keep getting a weird error message on the madusa when tyring to write a clean bios file.. Seems to read it OK. Have you encountered this before?
 

Anterweb

Member
Went to give this a go last night but.

Last time I tried it I had 2 other Airs on my shelf with the same logic board that I pulled the bios from, I now dont have these and stupidly diddnt save the bios dump to the PC. Do you have agood bios for this I could try please?

Thanks in advance,.
 

Anterweb

Member
This is really odd! after you mentioned check J6100 is clean I thought id just have a look at it under the scope, |"Board in case"

Looks immaculate! but whilst there I turn on using R5115/ pads, and it goes BOING and boots into desktop shocked I go to the kitchen and make a coffe.

On return its screen has gone off and its doing a quarter fan spin, So I power it off and try again, now back to original problem again, no matter what is or isnt connected or how I power it on I just get fan spin no boing no display,

Does this give us any more clues as to whats going on here?
 

2informaticos

Administrator
Staff member
Heat PCH/CPU with quality flux.
May have luck to be a problem caused by accumulated crap.

You can also try reballing SMC.
 

Anterweb

Member
Heated PCH and SMC with Amtech flux, Board looked a mess so ran it through the Ultrasonic,
Put back together and it booted fine and ran perfectly.

Half an hour later wouldn't turn on, couldn't even get a fan spin this time it just looked dead,

removed heat sink again loads more flux and a little more heat for a little longer on just the PCH, Cleaned up put back together and its been working perfectly all evening!

Crap under PCH maybe?

Let's see if it turns on in the morning ;)
 
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