A1932 820-01521 no power / no S5 voltages

[cruiser_]

hi there,

I have this 2008 macbook air with unknown history. No signs of spillage etc. No signs of previous work on the board. Absolute no runner, no signs of life.

Upon attaching the charger, 20V is negotiated and I got all the below voltages. The only wrong voltage was on PP1v8_SLPS2R_PMUVDDGPIO (short) which I temporarily fixed by removing C7800.

I am not getting any S5 voltages.

RECOVERY/Forced DFU starts off and cancels after some seconds with error 9 (failed to receive message from device).

Any help in suggesting next steps or confirming whether it's SSD(NAND) or T2 issue would be greatly welcome.

Thanks in advance


PP3V3_G3H_RTC 3.3
PP3V3_G3H 3.3
PP3V_G3H 3,0
PPBUS_G3H 12.6
PP5V_G3S 5.1
PP1V8_G3S 1.8
PP3V3_G3S 3.3
PP1V8_SSD 1.8
PP0V9_SSD 0.9
PPDCIN_G3H 20,5
PP2V7_NAND 2,49
P2V7NAND_EN 1.8
P2V7NAND_PGOOD 2.47
NAND_RESET_L - 1,79
PMU_ONOFF_L - 3,29
PPVDDCPU_AWAKE: 0,75V
PPVDDCPUSRAM_AWAKE: 0,81V

Also OK
+PP1v2_AWAKE +PP1v8_AWAKE
+PP3v3_AWAKEPP1v8_SLPS2R_PMUVDDGPIO
+PP1v1_SLPS2R
+PP1v8_SLPS2R
+PP0v8_SLPS2R
+PP0v82_SLPDDR
+PP0v9_SLPDDR
+PP1v1_SLPDDR
+PP1V25_SLPS2R_SMC_AVREF

[mon2]

Re: A1932 820-01521 no power / no S5 voltages

PP2V7_NAND 2,49
P2V7NAND_PGOOD 2.47

The above rails look low. Remove all power.

Meter in resistance mode (2k scale). Check the resistance to ground for these lines.

[cruiser_]

Re: A1932 820-01521 no power / no S5 voltages

hi mon2, I was hoping to get your attention, you're a real star of the mac issues solving

PP2V7_NAND - R beyond scale, diode 0,361->0,406 -> increases
P2V7NAND_PGOOD - R beyond scale, diode 0,158 -> 0,248V -> increases

[mon2]

Re: A1932 820-01521 no power / no S5 voltages

Hi. This is a lot of trial and error with some logic. Still very much in learning mode for these boards. Have not personally faced this case but do review the power supply power up sequence for your logic board here:

https://repair.wiki/w/A1932_2018_-_2019_MacBook_Air

See if it helps and post your updates. There are a lot of good techs here so perhaps more minds will help to fix this board.

[mon2]

Re: A1932 820-01521 no power / no S5 voltages

Also review this thread:

https://boards.rossmanngroup.com/thr...ly-dead.60588/

[cruiser_]

Re: A1932 820-01521 no power / no S5 voltages

Thanks mon2. I am all to familiar with these unfortunately.

If all SLP and AWAKE voltages are present, and a DFU revive fails, replace U7800 empirically. If the problem persists after replacing U7800, the T2 chip is the likely cause of the fault, and a diagnosis of a failed T2 chip can be made.

It seems my case is narrowed down to faulty U7800 or T2 but maybe there is something I missed? Also, I cannot find any more info on diagnosing T2.

[mon2]

Re: A1932 820-01521 no power / no S5 voltages

Do you have 20v negotiating on each type C port?

What is the current draw?

The _AWAKE lines' voltage look low as well.

Update - It is funny that you are reviewing U7800. Have a logic board in for repair which we suspect is also linked to this PMIC being defective as numerous rails from this component are not turning ON.

Are you aware of the details of this part ? It is very costly offshore ($30++ USD on Aliexpress) so trying to rip it off a 'locked PCB' in transit from Ebay.

What are the markings on your U7800 component ?

[cruiser_]

Re: A1932 820-01521 no power / no S5 voltages

Unfortunately I dont have these fancy USBC meters, so cannot say for sure what the draw is on the 20V.
On the regular USB 5V side I am getting 0.19A-0.24A (fluctuates a bit, should it?) on both ports (there are only two).
With Apple charger attached, for either of the ports I am getting 20,6V on PPDCIN_G3H_CHGR_AMON so I presume the negotiation works?

I was thinking about the low NAND voltages and AWAKE voltages; some sources suggest they should be 2.7V and AWAKE at 1.06V. However, looking at the schematics I am not so sure.
For the latter, my understanding of the schematic is the expected values are 0.625-1.06 & 0.8-1.06 for PPVDDCPU/SRAM_AWAKE, which mine correspond to.
For the NAND part, I saw some people reporting 2.5V on this allegedly 2.7V line. This still puzzles me a bit - perhaps time to go over the feedback line of R9070/R9071/R9073/R9072. It would be great if someone had values there.

U7800 wise (the PMIC chip). On my board it is 338s00267-a0. Feel a bit stingy about ordering and replacing this 30 US$ part out of sheer desperation

I am wondering about how the communication for DFU operation takes place.
At what point does the USB-communications (which I believe provide USB ids and initial reading for 'Apple Controller') 'turns' to T2 which then turns to NAND for writing? Maybe something off happens there?

[cruiser_]

Re: A1932 820-01521 no power / no S5 voltages

A bit of an update...
I reflashed the T2 ROM/SPI chip, the change now is the device boots up in DFU mode every time.

Tried restoring with either Apple configurator or idevicerestore.

The device now enters DFU, then Recovery mode, then RecoveryOS mode whlie being revived, however it does seem to have problems with the process.

..
default 14:18:43.083458+0100 com.apple.configurator.xpc.DeviceService tid:13317 - Recovery mode device connected
...
default 14:18:43.162226+0100 com.apple.configurator.xpc.DeviceService tid:195b - Data was : getenv ota-uuid
default 14:18:43.162290+0100 com.apple.configurator.xpc.DeviceService tid:195b - command device request for 'getenv ota-uuid' failed: 2008
default 14:18:43.162354+0100 com.apple.configurator.xpc.DeviceService tid:195b - Failed to copy env variable, error:21
...
default 14:18:53.695234+0100 com.apple.configurator.xpc.DeviceService tid:195b - RestoreOS mode device connected
...
default 14:19:04.085577+0100 com.apple.configurator.xpc.DeviceService tid:13323 - RestoreOS device removed before restored completed
default 14:19:04.187907+0100 com.apple.configurator.xpc.DeviceService tid:13323 - [PurpleReverseProxy]: Apr 05 14:19:04 com.apple.configurator.xpc.DeviceService[23347] <Error>: RPSocket.cpp:508(RPSocketReadBuffer): EOF on <RPSocket 0x7f982f525830: (null) fd=10>
default 14:19:04.188112+0100 com.apple.configurator.xpc.DeviceService tid:beaf - recv(8, 4) failed: connection closed
default 14:19:04.188332+0100 com.apple.configurator.xpc.DeviceService tid:beaf - unable to read message size: -1
default 14:19:04.188359+0100 com.apple.configurator.xpc.DeviceService tid:13323 - [PurpleReverseProxy]: Apr 05 14:19:04 com.apple.configurator.xpc.DeviceService[23347] <Error>: RPSocket.cpp:218(signal): No client callback, missing event 8 for socket 0x7f982f510850
default 14:19:04.188482+0100 com.apple.configurator.xpc.DeviceService tid:beaf - Failed to receive message from device, might be connection problem with USB host.
default 14:19:04.213857+0100 com.apple.configurator.xpc.DeviceService tid:beaf - <Restore Device 0x7f982f53e5a0>: Restore failed (result = 9)
default 14:19:04.213962+0100 com.apple.configurator.xpc.DeviceService tid:beaf - Can't send dump_console command since device is not in recovery mode
default 14:19:04.214050+0100 com.apple.configurator.xpc.DeviceService tid:beaf - AMRestorePerformRestoreModeRestoreWithError failed with error: 9
default 14:19:04.214303+0100 com.apple.configurator.xpc.DeviceService tid:beaf - State Machine Dump, status:ERROR - [stateFU remaining-cycles:1] -> [state:Recovery remaining-cycles:1] -> [state:RestoreOS remaining-cycles:0 (current state)]
default 14:19:04.214472+0100 com.apple.configurator.xpc.DeviceService tid:beaf - State is now set to error: AMRestorePerformRestoreModeRestoreWithError failed with error: 9

Similarly, with idevicerestore it seems it's failing around NAND operations:

Connected to com.apple.mobile.restored, version 15
Device 00008012-001171E20AC20026 has successfully entered restore mode
Hardware Information:
BoardID: 23
ChipID: 32786
UniqueChipID: 4910290261114918
ProductionMode: true
Previous restore exit status: 0x100
Starting Reverse Proxy
ReverseProxy[Ctrl]: (status=1) Ready
Checkpoint 1621 complete with code 0
Checkpoint 1540 complete with code 0
Checkpoint 1679 complete with code 0
About to send RootTicket...
Sending RootTicket now...
Done sending RootTicket
Checkpoint 1547 complete with code 0
Waiting for NAND (28)
Checkpoint 1549 complete with code 0
Updating NAND Firmware (58)
Checkpoint 1550 complete with code 0
Checkpoint 1551 complete with code 0
Checkpoint 1628 complete with code 0
Checkpoint 1552 complete with code 0
Checkpoint 1555 complete with code 0
Checkpoint 1662 complete with code 0
ReverseProxy[Ctrl]: Connection closed
ReverseProxy[Ctrl]: Terminating
ReverseProxy[Ctrl]: (status=2) Terminated

sometimes goes further:

Updating NAND Firmware (58)
Checkpoint 1550 complete with code 0
Checkpoint 1551 complete with code 0
Checkpoint 1628 complete with code 0
Checkpoint 1552 complete with code 0
Checkpoint 1555 complete with code 0
Checkpoint 1662 complete with code 0
About to send NORData...
Found firmware path Firmware/all_flash
Getting firmware manifest from build identity
Extracting LLB.j140k.RELEASE.im4p (Firmware/all_flash/LLB.j140k.RELEASE.im4p)...
Personalizing IMG4 component LLB...
Extracting DeviceTree.j140kap.im4p (Firmware/all_flash/DeviceTree.j140kap.im4p)...
Personalizing IMG4 component DeviceTree...
Extracting iBoot.j140k.RELEASE.im4p (Firmware/all_flash/iBoot.j140k.RELEASE.im4p)...
Personalizing IMG4 component iBoot...
Extracting sep-firmware.j140k.RELEASE.im4p (Firmware/all_flash/sep-firmware.j140k.RELEASE.im4p)...
Personalizing IMG4 component RestoreSEP...
Extracting sep-firmware.j140k.RELEASE.im4p (Firmware/all_flash/sep-firmware.j140k.RELEASE.im4p)...
Personalizing IMG4 component SEP...
common.c:supressed printing 14407486 bytes plist...
Sending NORData now...
Done sending NORData
ReverseProxy[Ctrl]: Connection closed
ReverseProxy[Ctrl]: Terminating
ReverseProxy[Ctrl]: (status=2) Terminated

So the device gets disconnected/reboot during the process.

I was monitoring the process on the mini scope and saw that all SSD voltages and NAND voltages are nice and steady.
What could be possibly interfering with it?