Macbook air 820-00165-A fixing

[bargo]

Throwing the kitchen sink at this.

with the lio cable connected, do you see the green led on for the MagSafe power head? Often the lio cable is defective between the 2 boards.

https://boards.rossmanngroup.com/thr...n-light.63378/

what is the voltage on SMC_RESET_L ?

With LIO cable connected it starts green after 2 seconds it goes to orange (battery disconnected)

SMC_RESET_L at 3.34v

EDP_PANEL_PWR is 0volt (this scenario EDP_PANEL_PWR stays low) only when LIO cable disconnects it goes high after few power cycles

[mon2]

Good. Follow this flow chart:

https://logi.wiki/index.php/G3_to_S3..._and_Broadwell

[bargo]

Does that mean, it needs to stay green before moving forward?

here it shows green then 2 seconds orange in that flow chart.

[mon2]

There is a lot going for the magsafe led turning green (first) and then switching to orange. This led color change is handled by a 1-wire communication protocol created by Dallas Semiconductor / Maxim and now owned by Analog (believe this is the order of acquisitions). That is, the SMC is performing these duties by sending out very time sensitive signals of high / low to toggle the LED. The orange color denotes the battery is low or missing - another good sign.

Does the green led turn OFF and then power cycle repeats? The flow chart is gold to follow. If you are power cycling, suggest to remove all power -> meter in resistance mode -> measure the resistance to ground of each and every inductor (grey in color usually). If the resistance is low -> check if the power rail that is linked to this inductor is a low voltage rail or not. If it is a low voltage rail then expect a low resistance on that rail - by design.

However, if the resistance is low and the rail is something like 3v3 then there is a shorted part on that rail. The current sense loop on that power rail is sensing this excessive current draw and powering down the local power rail, hence your power cycle loop. We have seen many A1466 logic boards with this fault due to shorted tantalum caps. Keep in mind that this macbook is relatively old so capacitors will age (some more than others). Tantalum caps which are polarized (+ and -), just short when they die. They are crap IMO. This is the #1 reason we do not use them at all in our product designs. We have products running 7-10 years 24/7 and still kicking. Japan banned their use ages ago. We prefer ceramic caps which are not totally innocent but less prone to this serious fault. A $0.50 USD part can kill a macbook or make it look like it is dead.

Confirm again that the led remains ON (does not matter if green or orange). If you have power cycling then the hunt is on for a shorted part. What is the voltage to ground of ALL_SYS_PWRGD ? This signal must be a stable 3v3 to denote that all power rails on the board are stable.


Another review should be on the SMBUS lines (SCL / SDA) that are used from the SMC to the ISL chip that creates the boosted voltage for PPBUS_G3H. If either of these lines is defective, the ISL will not be boosted.

[bargo]

Ok I think I miscommunicated something that made you think there is a power cycle of any kind, power cycle is a process where you shutdown and restart the machine which i do manually.

The light starts green 2 seconds later it goes to orange, all rails are fine and coming up, we dont have edp_panel_pwr if we connect LIO cable though it comes only without connecting the LIO cable.

So even Lid SMBUS work fine without the LIO cable.

I went through all the chart a year ago and validated all voltages are present

[mon2]

Test with another LIO cable. They are known to go bad. Even better to test with another known good power daughter LIO board that is used with this unit. Need to do a Costco run so will check later but review which signals that are on the main logic board on this LIO connector. Check in diode mode with and without the LIO cable.

Any partial or full fan spin? Any liquid damage?

personally never seen it but the flash may be corrupted. The a1466 is very well documented for repair cases on repair wiki, etc.

Do check again that the smbus lines on the battery connector are not being shunted to ground.

[bargo]

I'm testing with 2 different LIO boards and cables, same exact results. SMBUS lines seems to be fine according to what happens to battery reads. I did not find a flow chart for the EDP_PANEL_PWR signal and other important signals like EDP_BKLT_EN or the chime sound signal for example.

anyway this is my second bios trial, both have been cleaned. But maybe I will try an already cleaned image and update the serial number.

i hope i dont need to redo the SMC chip again anyway

[mon2]

Measure the voltage to ground of SMC_LID (J9500 connector = LIO connector on the logic board) with and without the LIO cable.

[bargo]

I just found that C1845 is missing, how critical is this 0.1uf badcap ? I will measure that after I get that cap inplace

[mon2]

It is not important. A single missing cap will not be missed.

[bargo]

I guessed its not important but i put it back on so it looks better. The voltage to ground for SMC_LID is 3.41v with LIO and without is 3.38v

[mon2]

Remove all power. Measure the resistance to ground of R5171 pin #1 = SMC_LID. Measure with and then without the LIO cable attached.

[bargo]

Remove all power. Measure the resistance to ground of R5171 pin #1 = SMC_LID. Measure with and then without the LIO cable attached.

Both reads similar 450k to 480k ohm

[mon2]

Is the trackpad connected or disconnected? Disconnect it if it is attached. It is not required at this time.

[bargo]

same thing, do you know if there is any available bios for 7,2 the ones I found here are for 7,1




One more thing, do you know if any macbook air early 2015 (known by serial number, I have no body) that comes with I-5257U processor, apparently this CPU is coming out from a MacBook Pro 13 inch 2015

Maybe I need a MacBook pro bios instead. (I bought it like this, CPU have been installed on this board but apparently the I-5256U processor never came into Macbook Airs)

I will just flash that bios

[bargo]

same thing, do you know if there is any available bios for 7,2 the ones I found here are for 7,1




One more thing, do you know if any macbook air early 2015 (known by serial number, I have no body) that comes with I-5257U processor, apparently this CPU is coming out from a MacBook Pro 13 inch 2015

Maybe I need a MacBook pro bios instead. (I bought it like this, CPU have been installed on this board but apparently the I-5256U processor never came into Macbook Airs)

I will just flash that bios

NO WAAAY MAAAN

I have a screen now, i can see the flashing disk icon without SSD. no chime still but USB stays active, no keyboard light.

Once we put SSD the screen changes to no ENTRY without grey background then shuts down after few seconds

Another disk is being in trial, the screen remains black longer now

[bargo]

Ok interestingly the mac goes into the linux grub, I remember the last time this disk had both linux and osx, now its strange that the bios tells grub that what used to be hd0 is now at hd7, seems to be related to the bios change, so it could be i just need to find the correct bios settings for this compo, maybe some stuff needs to be copied from the macbook air bios to this one, have little experience man

[bargo]

ok i was wrong that CPU is actually Core i5-5250u according to linux, so it must have been examined otherwise by me, but now with macpro 12,1 bios the machine works, like most of the important things work, other than it thinks that it has 16gb while it have 8gb.. Any good known bios for this version with clean me or without its ok i can clean it,

Apple MacBook Air 7.2 A1466 13.3

[mon2]

Post the same request in the dedicated bios forum.

So the earlier failed bios attempts were for the wrong logic board?

[bargo]

No its the opposite the earlier failed bios attempts were all for the correct bios and logicboards according to the posts i found for that logic board in the title, but the wrong bios worked.