MacBook Air A1932 2019 display remains black after reopening the lid

[MicroSMD Lab]

Hi, I'm bumping this topic because I have a similar situation but the one I'm working on, the display remains black after reopening the lid. If I disconnect the battery and boot with the charger everything works until I close the lid. If I shut down with the lid open and press the power button everything works. It came in for liquid damage with a burnt audio board. I think the hall sensor in the right speaker is faulty, but I didn't do any tests yet. I'm interested in having the sleep function work with one sensor until I get the replacement speaker (assuming the speaker hall sensor is defective. I will conduct tests as suggested in this post to confirm, but I'm asking for assistance to operate the sleep function with one sensor... if possible...

[mon2]

Re: MacBook Air A1932 2019 No Sleep Mode

Carefully measure the voltage to ground of the highlighted signals with the lid open.

Post each measurement. If the lid is OPEN, each signal pin should be a logic '1'.

[MicroSMD Lab]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

Finally got around to this unit again
SMC_LID_LEFT - R4804 - Open - Pin1 = 1.79V, Pin2 = 1.79V
Close - Pin1 = 0.00V, Pin2 = 0.01V
SMC_LID_RIGHT - R4805 - Open - Pin1 = 0.14V, Pin2 = 0.14V
Decided to replace right speaker since the audio board was damaged from a liquid spill.
R4805 now reads - Open - Pin1 = 1.46V, Pin2 = 0.99V
Close - Pin1 = 0.02V, Pin2 = 0.03V
https://logi.wiki/index.php?title=M1...e_view_desktop states "Low PP1V8_AON (1.5 or 1.4v due to bad cap near regulator) would cause partial LID problems like disabled touchscreen on Toucbar, random no haptic click" not sure if this is related. Also on another page https://logi.wiki/index.php/DFU_Mode_Restore_(Macs) under the "scenarios for restore" section describes a similar issue but the voltage was 1.1V.
As always any advice on how I should proceed is much appreciated, thanks in advance.

[mon2]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

You have a few choices on this fix.

When you open the lid, what is the voltage to ground of IPD_LID_OPEN ? This is the output of the dual input OR-gate (U4802).

This logic level should be ~1v8 when the lid is OPEN; ~0 volts when the lid is CLOSED.

Next, remove all power -> meter in resistance mode -> measure the resistance of R4805. This resistor may be defective and/or U4802 is defective and causing a larger voltage drop. That is, when the lid is open, the same voltage of ~1v8 should be present on the SMC_LID_LEFT and also at SMC_LID_RIGHT.

From the posted voltage measurements, the SMC_LID_LEFT is working properly.

The parts in this region of the board are extremely tiny (0201) and not simple to solder / desolder.

Confirm the voltage to ground of IPD_LID_OPEN to continue this review.

[MicroSMD Lab]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

IPD_LID_OPEN is 1.79V with the lid open, 0V when the lid is closed and 1.79V when the lid is reopened but there is no display. R4805 measures 7.67kohm while R4804 measures 9.99kohm.
The first time I measured IPD_LID_OPEN, I took the reading from pin 32 of J6700 with the connector disconnected, the voltage was 1.79V with the lid open and closed and the display didn't come off.

[mon2]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

When the lid is open - shine a flashlight / phone in torch mode onto the front face of the display.

Can you see any of the usual graphics on the display? That is, only backlight is missing?

Your caps key led is able to toggle on/off ?

[MicroSMD Lab]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

Yes only backlight is missing and caps key led is able to toggle on and off

[mon2]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

Confirm that the backlight IC receives an enable signal to enable the backlight.

Also, with no power, measure the resistance to ground of the actual backlight power rail.

Post the measurements.

[MicroSMD Lab]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

Just to confirm, are you referring to pin 17 of U8400 (LP8548) and PPVOUT_S0_LCDBKLT

[mon2]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

Yes.

[MicroSMD Lab]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

PPVOUT_S0_LCDBKLT to gnd is in the order 100kohm. Backlight enable is tricky since it on the top side of the board and this board is not booting without a battery. Any suggestions? should I run a wire?

[MicroSMD Lab]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

I ran a wire and backlight enable is 3.28V. I saw a thread with a similar issue on the rossmann forum but in that case the facecam did not work (can't seem to find it now) so I turned on facetime and got no camera detected.

[MicroSMD Lab]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

Just checked the microphone is not working also... maybe related to U4850? The first time I checked the backlight enable I got the voltage after reopening the lid but all other times after the enable has been 0V. I also noticed that after reopening the lid, the caps lock takes about 3 or 4 presses to respond, at first I thought it was just a sticky key but when it does light up, that's when I see an image with no backlight, this image goes away after a couple seconds though and seems to return only when I press the caps lock until it lights up again.

[MicroSMD Lab]

Re: MacBook Air A1932 2019 display remains black after reopening the lid

Finally got my donor board, replaced U4850 and everything works. I did a diode mode check on J6100 while I was waiting for the donor and pin 27 (SMC_LID_RIGHT) gave a reading of 0.167. It should be closer to 0.643, thanks to logiwiki. When I replaced U4850 the diode mode reading went up to 0.593.
Thanks Mon2 for all your guidance!