Macbook Air 13 A1466 820-3437-B and 00165-A

[toinounet21]

Hi, I picked up a big batch of Macbook Air A1466 and just tried them, a lot boot in SMC Bypass mode, I have known this procedure for a long time but I still have doubts about the meaning. What does it mean if it boots correctly in this mode? I assume everything is OK apart from the SMC? I've checked on one every pads around it all seems to be OK, except PROCHOT but if I'm not wrong it comes from the SMC?

Thanks for your answers

[MuertoGB]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

Incorrect, it may not be the SMC but a tripped sensor, or something else downstream that the SMC does not like. Remember, its the SMCs job to detect faults and halt power if necessary.

Visual inspection is your best starting point. Check power to the SMC, do you have MagSafe charging light? Do you have a short circuit on PP3V3_S5_AVREF_SMC?

After inspection, what is the power draw from your PSU from each board with the battery disconnected?

[reformatt]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

I just picked up 20 boards myself, all were fixable. 820-00165 boards with 8GB are the most valuable, as these can run Monterey natively.

As MuertoGB, the most common issue when it works in SMC bypass is a missing PP3V3_S5_AVREF_SMC. This is usually a shorted cap next to the SMC. If there is liquid damage there, then there is likely to be crap under the SMC as well. I used to reflow these, but now reball them instead. You cannot see corrosion under the chip or pads without taking it off.

The biggest weakness of all MAC boards are the exposed copper test points. These often get eaten away by corrosion etc, and most of the boards I fix have that issue.

[toinounet21]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

Thanks for your answers guys, I've just checked one board for now, PP3V3_S5_AVREF was one of the first checks and is OK, I will check sensors, BTW I have at least 3 boards which doens't starts, starts in SMC bypass mode and have backlight issue, could there be any link with the SMC or just boards with this fault that were maybe put aside and dirty over time?

Muerto, I just saw your SMC reprogramming tool, I did something similar a few years ago with SMCs bought on Aliexpress and everyone here thought I was crazy xD, never had the time to do a tutorial and I completely forgot the procedure, I will look at it when I will have time.

[toinounet21]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

After inspection, what is the power draw from your PSU from each board with the battery disconnected?

What do you mean? Is there a tool to measure current like on the USB-C Macbooks? I haven't done any repairs for several years and may not be up to date

[MuertoGB]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

What do you mean? Is there a tool to measure current like on the USB-C Macbooks? I haven't done any repairs for several years and may not be up to date

Yes, cut the cord from a faulty MagSafe 2 85W charger, this can be used with a bench power supply.

[toinounet21]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

Oh OK I see, which voltage precisely and what are the intended values, what they means?

BTW how to check current sensor?

[reformatt]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

Personally I use a USB-C to Magsafe 2 adaptor via a Uni-T ammeter. I use a 87W USB-C Apple adaptor as this supplies up to 4A. Some of the other USB-C power supplies I have struggle with 4A on MAC's for some reason, so I just stick to the Apple one.

Current (without battery connected) will tell you a lot of what is going on. A 820-00165 board without display/battery/SSD will initially will go to 520ma or so, bounce around a bit, then settle to 320ma once it's posted and attempting to boot. Chipmunk USB tester is great for bench work, as you'll get a green flashing LED when the board is probing for something to boot off. Static 420ma is usually bad RAM.

Sensor issues usually result in a booting machine but max fan speed and throttled CPU. If it's not booting but work in SMC bypass, first thing for me is to take off the edge bonding and reflow the SMC. If that fixes it, I recommend you pull it off and reball it.

[toinounet21]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

Ok, I will try that, hum for the three first boards it's fun because the three had just one little oxydation point, after have cleaned and replaced the parts concerned, the problem stay the same on the three

[toinounet21]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

Just tested on the three boards, one miraculously came back to life, probably after having finished drying following ultrasonic cleaning, the other two stagnated at 27/29mA

[toinounet21]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

Hum... I'm really not up to date... I just realized that 00165-A that I was thinking of starting only in SMC bypass mode just doesn't start with the charger I used... I really don't know why some boot with and some doesn't (85W, don't know if it's original or not, but the other one I used with which all boards boot is definitely not an original, just a good copy)

[piernov]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

https://logi.wiki/index.php/User:Pie....2C_what_do.3F

First thing is to be 100% sure you are using a known good genuine Apple Magsafe of the correct generation and power rating. Using a lower power rated Magsafe than what is required will prevent the board from going to S4 state or higher when battery is dead/removed/discharged. Refer to https://support.apple.com/en-us/HT201700 . Using a non-genuine Magsafe as well as using a Magsafe1 instead of a Magsafe2 can cause the same issue with some boards (most notably 820-00164, 820-00165 and 820-4924 but others can be affected too). In both of these situations, BATLOW# (PM_BATLOW_L) will stay low.

[dellxps15]

Re: Macbook Air 13 A1466 820-3437-B and 00165-A

make sure no backlight is actually the problem and not cpu not working.