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MBA A2179 - No water, No drop - Turned off while working, doesn't turn on. Takes current, no heat.

S

samstown

Member
Hello,

I got my first dead MBA 2020 A2179 and I don't have schematics.

MacBook looks perfect, no water, no drop, nothing bad on motherboard. Customer said he was working and then sudden death. Now, when pressing power button, nothing on the screen, no fans.. but the little LED near CPU on Fan side is on, it's a very tiny LED, you almost need to turn light off on the room to see that the LED is on... but it's on.

I've connected USB-C current tester, I can see it goes to 0 when I press the power button long time, after 1 seconds it takes again ~950 mA. I can't feel heat anywhere. So far, the board still in place, I didn't removed it. I tried removing battery connector, doesn't help.

I want to be really carefull as device still under warranty, customer want DATA recovery.

Thanks
Sam
 

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2informaticos

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

Try to find 820-xxxx code of your board, if you want to get schematic.
However, not easy to find schematic for 2020 model.

Try Revive option in DFU mode.
Do NOT use Restore, as it will erase SSD!
 
S

samstown

Member
Thank you Admin, happy to be on this forum.

I'll take the board out and see if I can identify the model.

I've tried DFU, no luck, doesn't get detected in AC2. I am pressing power + right shift + left CTRL & Option for 10 secs then release those three keys and keep power pressed.

Is there any other key shortcut I could try ? Any idea what are most common "sudden death" on those machine ?
 
2informaticos

2informaticos

Administrator
Staff member
Read here about DFU...

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...
boards.rossmanngroup.com boards.rossmanngroup.com

If you cannot access DFU, check if all AWAKE and SLPS2R voltages are present.
 
S

samstown

Member
Hello.

I got a MacBook Pro and I did "Revive" from DFU. Process was ok. After that, I still have a black screen but I can hear a strange noise when powering the MBA. It's a fast "clic-clic-clic" this is exactly the noise customer reported after sudden death. I would like to attached the audio/vidéo (forum doesn't like mp4 format), I know it doesn't really helps... but still.. what I hear comes from... I think ... from CPU.

Using AP2 whith patient MacBook Air in DFU, there's an option to "backup" would that help to recover data ?

Thanks
Sam
 
2informaticos

2informaticos

Administrator
Staff member
Do you get voltage on big coils?
Check for short; is what the sound points to.
 
Last edited:
S

samstown

Member
thanks. Big coils have voltage, in red on the pics. I haven't find short yet. This "clic, clic" sound should come from a filter ?

So board is 820-01958-A
 

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S

samstown

Member
Thank you. So on the other side, I found two shorts, I think those in red are filters, right ? They have 0 V and are short to GND. So I should remove and replace those or check anything else before ?

I can't find what component make the "clic, clic" noise, it's really hard. The noise start always after 7 seconds. I think it's near the short filter but impossible to locate it properly.
 

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2informaticos

2informaticos

Administrator
Staff member
These caps should be placed on CPU voltage.
Could look like short for you; maybe is not, in fact.
Why didn't reply to piernov post???
 
S

samstown

Member
2informaticos said:
Can you post exact ohm resistance???
I talk about the 4 "R33" marked coils in the second picture...
Click to expand...
Thank you for your patience, sorry.... You mean those 4 R33 ? I guess not those... as I've mentionned Voltage and resistance in previous pics. If not, I am not sure which one, can you show me on pics, I wrote 0 Ohm, they have 0,4 Ohms to be exact.
 

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2informaticos

2informaticos

Administrator
Staff member
0.4 ohm is short, dead CPU.
This is the resistance you get with multimeter leads only; so external resistance is 0 ohm.
 
S

samstown

Member
Thanks, bad news. I don't really care about the device but need data recovery ? MBA goes to DFU, anything we can try ? Can we not replace CPU ?
 
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