Macbook 820-01700 Stuck at 5V

**powerblackout** · 01-10-2022, 12:12 PM

Re: Macbook 820-01700 Stuck at 5V

When I plug the motherboard into another macbook to do a DFU restore it immediately shows up on the other machine as DFU. When I tried to do a revive I get an error about expecting recovery mode.

When I start the revive the board goes to 20V 0.01A then I get an error

"Unexpected device state 'DFU' expected 'Recovery' (Probably forced into DFU mode externally) [com.apple.MobileDevice.MobileRestore – 0xFAE (4014)]"

**mon2** · 01-10-2022, 12:25 PM

Re: Macbook 820-01700 Stuck at 5V

No personal experience with this but @Piernov noted that T2 bridgeOS must be there for the 20V power delivery contract to work on this logic board. So your approach is logical.

See here:
https://boards.rossmanngroup.com/thr...roblems.61662/

also T2 based.

**powerblackout** · 01-10-2022, 12:57 PM

Re: Macbook 820-01700 Stuck at 5V

Thanks, after giving that a read my 0V9_SSD is 0.00v, and has a 0.342 diode reading. It goes into DFU mode without having to press any keys, it happens when the board is outside the case disconnected completely. Is there something on the board that can do that?

My AWAKE and SLPS all look fine I think:
PP1V8_AWAKE - 1.8v
PP1V2_AWAKE - 1.19v
PPVDDCPUSRAM_AWAKE - 0.8v
PPVDDCPU_AWAKE - 0.756v
PP3V3_AWAKE - 3.37v

PP1V8_SLPS2R - 1.86v
PP0V8_SLPS2R - 0.797v
PP1V1_SLPS2R - 1.1v
PP1V25_SLPS2R_SMC_AVREF - 1.25v

**powerblackout** · 01-10-2022, 10:57 PM

Re: Macbook 820-01700 Stuck at 5V

After more researching it appears U9500 controls U9580 via the SSD0_VR_P2V5_EN which on this board is always 0v, would this mean the U9500 is having issues?

**mon2** · 01-11-2022, 06:06 AM

Re: Macbook 820-01700 Stuck at 5V

Yes, it may be. Confirm the presence and voltage of PP3V3_G3H_SSD0_SNS.

**powerblackout** · 01-11-2022, 08:47 AM

Re: Macbook 820-01700 Stuck at 5V

PP3V3_G3H_SSD0_SNS is present, 3.38v.

I didn't realize there was another set of these for SSD1, I checked these two
SSD1_VR_P2V5_EN - 0.0v
PP3V3_G3H_SSD1_SNS - 3.38v

What are the chances that both U9500 and U9000 are broken? Or maybe I need to look further upstream for something that controls both of these?

**powerblackout** · 01-11-2022, 05:08 PM

Re: Macbook 820-01700 Stuck at 5V

Is it normal that the macbook immediately shows up in apple configurator 2 as soon as i plug it in? i don't have to do the keyboard shortcuts.

If I plug the charger in, then start the revive process, the charger will jump to 20V 0.01A, but PPBUS_G3H will still be 12.3V

**mon2** · 01-11-2022, 06:43 PM

Re: Macbook 820-01700 Stuck at 5V

Not familiar with the Configurator 2 tool so wait on others to comment.

20V 0.01A, but PPBUS_G3H will still be 12.3V

This is correct that the power delivery contract with 20V is ultimately selected by the ACE controller and the PPBUS_G3H steps this voltage down to 12v3. Thought I read on Logiwiki that 12v6 is the sweet spot after some more states are enabled on the power rails. Either way, you are very close on the PPBUS_G3H rail.

reference:
https://logi.wiki/index.php/PPBus_G3H

**powerblackout** · 01-11-2022, 07:11 PM

Re: Macbook 820-01700 Stuck at 5V

https://apps.apple.com/us/app/apple-...37126344?mt=12 the app that allows DFU revive/restore?

**powerblackout** · 01-11-2022, 09:25 PM

Re: Macbook 820-01700 Stuck at 5V

Do you know what controls the creation of the 0.9, 1.8, 2.5v from this chip? I checked SSD_PMU_RESET_L (1.8v), is it controlled via the SCL/SDA communication?

Attached Files

**powerblackout** · 01-11-2022, 10:52 PM

Re: Macbook 820-01700 Stuck at 5V

Another discovery. I hooked my oscilloscope up to I2C_PWR_SDA and I2C_PWR_SCL lines going to the charger, i see them go up to 1.785v but they do not have any traffic on them. I see i2c is controlled by T2 chip, this would suggest why battery isn't charging and why U9500 isn't turning SSD on? because T2 is messed up and not communicating over i2c?

Another discovery! I put the ammeter between the two machines, when the revive process starts the ammeter reads 4.93v 0.2a, and the T2 chip gets to about 80 F while the rest of the board is at 70 F. While it is doing this the PP2V5_NAND_SSD0 etc are still 0

**powerblackout** · 01-12-2022, 12:41 AM

Re: Macbook 820-01700 Stuck at 5V

I got it up to 4.46V 1.03A using a beefier usb cable. it appears it is charging the battery from the other macbook, I see the PPBUS_G3H voltage rising and I see i2c traffic on the ribbon going to the battery. This all only happens once a revive is started.

The DFU revive failed with error code 4005, I finally found a site that had some information on what that means https://logi.wiki/index.php/DFU_Mode_Restore_(Macs)

4005 = SSD not found.

So if T2 chip is actually starting to be revived, but can't find SSD for the T2 partition, and i2c appears to be functioning, where else should I look to find why it can't turn SSD on? Why U9500 Why!

**mon2** · 01-12-2022, 06:51 AM

Re: Macbook 820-01700 Stuck at 5V

U3900 (SMC) is the I2C bus master and the voltage readings for I2C_PWR_SCL and I2C_PWR_SDA look good.

I got it up to 4.46V 1.03A using a beefier usb cable.

This voltage sounds low. Personally have not yet used the configurator 2 tool but working on some T2 logic boards now so may have this need.

SSD_PMU_RESET_L is driven by U3900, J32 ball (marked as OUTPUT).

Meter in resistance mode, remove all power. What is the resistance to ground for PP2V5_NAND_SSD0 ?

Attached Files

**powerblackout** · 01-12-2022, 08:29 AM

Re: Macbook 820-01700 Stuck at 5V

Measured SSD_PMU_RESET_L it is 1.8v, the L means it pulls the line to 0v when it wants the chip to reset? So 1.8v means it should be working?

Resistance for PP2V5_NAND_SSD0 immediately after i remove power is 62 ohms. is 87 ohms 30 seconds later and keeps rising. 1 minute later it's passed 100 ohms.

**mon2** · 01-12-2022, 09:57 AM

Re: Macbook 820-01700 Stuck at 5V

Resistance looks ok.

Confirm the voltages for the attached locations on U9580 which creates this 2v5 rail for the SSD.

Attached Files

**powerblackout** · 01-12-2022, 02:49 PM

Re: Macbook 820-01700 Stuck at 5V

PPBUS_G3H_SSD1_SNS - 12.3v
PPBUS_G3H_SSD0_SNS - 12.3v

SSD1_VR_P2V5_EN - 0.0v
SSD0_VR_P2V5_EN - 0.0v

SSD1_VR_P2V5_EN_R - 0.0v
SSD0_VR_P2V5_EN_r - 0.0v

**mon2** · 01-12-2022, 03:29 PM

Re: Macbook 820-01700 Stuck at 5V

Remove all power.

What is the resistance to ground for the following ?

SSD1_VR_P2V5_EN
SSD0_VR_P2V5_EN

Technically, these are enable pins for the local 2v5 regulators. If the resistance on this rail is not low, then you could in theory, remove the series resistor (R9098 for SSD1; R9598 for SSD0) bridging the driver & this local TI regulator -> then hard strap the enable pin to be logic high to force it always ON. This in turn should turn on the regulator to power on the SSD (of your choice).

The enable pin will consider a voltage > 1V to enable. You can strap the ENABLE pin to 3v3 on the board.

If you decide to do this, ping back so we can agree on a proper location for this rail.

Attached Files

**powerblackout** · 01-12-2022, 03:45 PM

Re: Macbook 820-01700 Stuck at 5V

SSD1_VR_P2V5_EN - 3.2 megaohms
SSD0_VR_P2V5_EN - 3.1 megaohms

Yes I could force enabling the pins to see if the SSD even works. Would this be a permanent solution?

**mon2** · 01-12-2022, 03:55 PM

Re: Macbook 820-01700 Stuck at 5V

First, I would test it but gathering that with the power rail always enabled, the battery will drain faster.

However, this could be a case of the chicken and the egg - you need to manually enable the SSD so that you can restore the T2 firmware and after this is resolved, apply the series resistor back onto the logic board and test again.

In theory, this may be the resolution. Very curious and wanting to hear of your success.

Macbook 820-01700 Stuck at 5V

Macbook 820-01700 Stuck at 5V

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