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Old 05-21-2022, 03:11 PM   #1
mferna14
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Default MacBook Air A1932 No Display

Hi All, I am working on a MacBook Air A1932 (2018) No Display, motherboard 820-01521-A. It is totally clean & no sign of any liquid spill on it, like new. I notice that this notebook is going easily into DFU mode & while trying to restore, it give me the error, please check photos. In the background all seems to be working, CPU gets hot & the trackpad vibrates & the fans moves too. What can be the problem, any help would be greatly appreciated. Thanks
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Old 05-21-2022, 07:34 PM   #2
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Default Re: MacBook Air A1932 No Display

Error 21 resolution is posted here:

https://logi.wiki/index.php/DFU_Mode...roubleshooting

The T2 rom dump is available here:

https://www.badcaps.net/forum/showthread.php?t=104860

But note that a special socket will be required to host this tiny and flash device.

Even more important...the flash operates at 1v8.

Be sure to confirm if your programmer can support this low voltage and flash part number.

Last edited by mon2; 05-21-2022 at 07:50 PM..
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Old 05-21-2022, 09:36 PM   #3
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Default Re: MacBook Air A1932 No Display

Thanks "mon2", really appreciate. I had a feeling it has something to do with the T2 Rom Chip. Thanks for all the information. I saw the programmer unit for these chip, they are costly! Will the ordinanry SPI programmer not work to program these chips if I change the programming voltage to 1.8v???
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Old 05-21-2022, 11:01 PM   #4
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Default Re: MacBook Air A1932 No Display

Which programmer do you own?

My concern is that while the Vcc (power) may be 1v8, the spi interface lines from the bus master (programmer) must also be swinging at the same levels.

To handle this properly, logic level translators must be used or the programmer interface should have its Vio rail operate at 1v8. Then, the flash will see the safe logic levels and can be powered at 1v8.
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Old 05-22-2022, 09:45 AM   #5
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Default Re: MacBook Air A1932 No Display

In a correction to my earlier post - I linked the CD3215/3217 ROM dump. Such rom dumps are used to correct the power delivery firmware used by the ACE controller.

Respectively, if I understand the wiki page correctly, you require the T2 ROM dump for your logic board. No experience with this topic yet but assuming that the best approach is to find a dump from a logic board of the same.

On Tuesday - will check if we have this model which I believe we may at the office.
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Old 05-22-2022, 11:42 AM   #6
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Default Re: MacBook Air A1932 No Display

I am using the Universal Programmer RT809H Serial ISP Programmer & the T2 chipsets W25Q80D & AT25SL321(ISP) description is there in the programmer software. Now I think I just need this socket "A1989 Rom Socket Assistant U2890 Notebook Chip W25Q80DVUXIE Adapter USON 2x3 0.5" available on eBay. Maybe I can give it a try, never know might have a solution in hand.
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Old 05-22-2022, 12:11 PM   #7
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Default Re: MacBook Air A1932 No Display

Hi. Yes, the linked adapter should work for your use.

The schematic shows U2890 as W25Q80DVUXIE. Datasheet is attached.

Upon review of the schematic, the Vcc for this flash device is 3v3 and not 1v8 as originally thought.

It should work as noted.

Comment: We may be indexing the wrong flash device - this the THUNDERBOLT flash which is used to hold the firmware for the ACE controllers (CD3215).

The T2 rom I have read is 1v8 so for that we DO require a level translation IC to convert your 3v3 signals to 1v8 else the flash device can be killed.

Will search some more...

Update: you require a 3x4mm socket like this one:

https://hklrf.com/T2-Rom-EFI-Socket-...pter_4519.html

BUT - big BUT again, there are no logic level translators on this passive PCB. So if your programmer shoots out 3v3 signals - it will kill your flash device !!

You will need to check if your programmer can support 1v8 target flash devices before proceeding.
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File Type: png t2_rom.png (101.3 KB, 17 views)
File Type: png t2_rom_dimensions.png (285.5 KB, 13 views)
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File Type: pdf w25q80dv_dl_revh_10022015-1489677 (1).pdf (2.17 MB, 6 views)

Last edited by mon2; 05-22-2022 at 12:17 PM..
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Old 05-22-2022, 06:31 PM   #8
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Default Re: MacBook Air A1932 No Display

T2 rom appears to be @ U4770.

See attached.

p/n MX25U3235F (1v8 for the Vcc)
4MX8

Check to see if your programmer can support this device.
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Old 05-22-2022, 07:38 PM   #9
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Default Re: MacBook Air A1932 No Display

mon2 your SURPERB knowhow & knowledge makes me crazy at times... You really put a lot of thinking & reading in all this, you really are an ASSET for Badcaps. Anyway I have read all what you send me & am going to order some W25Q80DV rom chips which is listed on 820-01521-A schematics, infact I will order both, the "MX" series too. Trying would not hurt, & in this way if this works everyone in the forum will know how to do it next. Thanks for all the help., really appreciate you helping me.

Last edited by mferna14; 05-22-2022 at 07:46 PM..
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