820-01814 No image on LCD and USBC ports acting strange

[samolo75]

Hi, I hope you are doing great,
I am confronting this weird behavior from this MBP from 2019.
The motherboard is 820-01914A MBP 15inch 2019
The initial symptoms the user told me was that from one day to another the display was just black and the toucchbar would show only the ESC button.
Connecting an external monitor they wiped everything and installed again. The computer boots but "same" thing. Now with external monitor you can "use" the system. The backlight from the internal display works and reacts when changing the brightness, but stays black no matter what.
I found another weird behavior of the USB C ports. The ones on the right can be used only for charging the laptop or charging your phone from them, but they will not detect anything else (they do detect the charger and set the charger to 20V and get the right current).
The USB C ports on the left will detect the USB hub and display to the HDMI monitor connected to it, but will not detect a mouse connected to it, at least not right away. It happened to me once that I was digging around the settings and all of the sudden after 20min or so playing with the system the mouse was detected and a window popped up to set it up.
I don't think both issues are related, but I am still learning.
I measure the 3.3 and 5V going to the display and all looks good. I have being trying to deal with the display issue first because I do not even know where to start with the USB C weird behavior.
Visual inspection does not show any signs of water damage, just a bit dusty, but looks pretty good. When I dismounted the USB C ports I did find some possible water damage, not much, and it was actually on the USB ports that work the best, not on the ones that only charge.
I would appreciate any ideas!! Thanks you!!

[mon2]

Re: 820-01814 No image on LCD and USBC ports acting strange

You can check the USB ports in diode mode.

Remove all power. Meter in diode mode.

Red meter probe, yes red to ground.
Black meter probe to D+ of the USB connector or ESD tvs diode.

What is the reading? Continue to test each port and also the D- pins, CC1, CC2, etc.

Post each measurement.

Can you confirm the 820-**** number of your logic boards? You have posted 2 different numbers.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

Thanks for the help. I made the measurements. Something looks off. Sorry, I confirm that the board is 820-01814-A

XA USB BOT N = 0.3
XA USB BOT P = 0.3
XA USB TOP N = 0.3
XA USB TOP P = 0.3
XA CC1 = 1
XA CC2 = 1

XB CC1 = 0.9
XB CC2 = 0.9
XB USB BOT N = OL
XB USB BOT P = OL
XB USB TOP N = OL
XB USB TOP P = OL

TB USB BOT N = OL
TB USB BOT P = OL
TB USB TOP N = OL
TB USB TOP P = OL
TB CC1 = 0.9
TB CC2 = 0.9

TA CC1 = 0.99
TA CC2 = 0.99
TA USB BOT N = OL
TA USB BOT P = OL
TA USB TOP N = OL
TA USB TOP P = OL

Do you think this can be related to the display issue?
Edit: I reflowed two of the CD3215 and nothing changed

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

Sorry. I am sure I measured the thing correctly. I did it again and for the AX P and N (from what I see those are D+ and D-) that I would get 0.3 I was getting now OL. The XA and XB both work for charging and with the USB hub connected to a monitor. the TA and TB only work for charging (those are the ones I reflowed with no changes, still just charging). So it looks like all of them measure more or less the same.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

New update. I tried the DFU restore. Nothing changed. Interestingly I had to use one of the ports that was initially not working for it and it worked, at least it looked like it worked. The process stopped in the middle when the faulty computer was restarting and then I had to restore using a external monitor and disconnecting the internal monitor to see anything on the screen.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

EDIT from the previous post. I had to use one of the "working" USB ports.

[mon2]

Re: 820-01814 No image on LCD and USBC ports acting strange

The diode readings look to be ok. If very close to zero then considered to be faulty.

Review this thread:

https://www.ifixit.com/Answers/View/...during+startup

It is one that we will follow soon for a logic board that went south after the client attempted some firmware update. In summary, we brought in a new touchbar but always got stuck with this fault which appears to be the FIRMWARE inside the touchbar being out of sync. @Piernov mentioned this about a year ago when we worked on the unit last.

Either way, attempt this process to see if it can properly update your DFU based firmware.

Do update this thread with your progress.

PS: Review the solution by Gurpreet Singh.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

I tried DFU and reinstalled mojabe and the problems is the same. I tried the FT Camera and does not work either. I connected the external monitor cable, connected a external monitor. As before backlight is on, no image on the LCD and started Photo Booth using the other monitor and it says that there is no camera connected. I was not able to find the schematics of what happens on the Display side.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

@mon2 thanks for the help. For the solution proposed about reinstalling the latest software I got a doubt. In my case the problem is with the screen and not the touchbar. The problem I have is that when the internal display is connected and I try to go on those recovery modes, I see nothing on the external monitor. I need to disconnect the internal monitor to do so, but if some sort of firmware is missing in the internal monitor, how do I do it to install the software and have the monitor connected? Shall I try to do a hot plug?
Something I observed, I am not sure how important it is. If I connect the internal monitor, right at the times the backlight turns on, there is a dim white vertical line in the middle of the screen that goes dims down pretty quick and disappears.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

I manage to put the macbook in safe mode (display connected) and install Ventura (from Mojabe). After a while of the installation process it is still the same but in Ventura. Internal LCD and FT cam not working.

[mon2]

Re: 820-01814 No image on LCD and USBC ports acting strange

right at the times the backlight turns on, there is a dim white vertical line in the middle of the screen

The LCD is damaged (period). The LCD has to be replaced.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

The LCD is damaged (period). The LCD has to be replaced.

This is also what I am suspecting. There is no signs of the screen being smashed or anything. Would that explain that the FT Cam also does not work?
Is there a chance to get the schematic and boardview of the board that goes with the display?
Thanks again for your help

[mon2]

Re: 820-01814 No image on LCD and USBC ports acting strange

For the display repair, there are 3 solutions:

1) (hard way but cheaper; takes longer) - you will purchase only the LCD and carve away the layers that build up the display assembly. Review the videos by Master Liu on Youtube. Not for the faint of heart. We do want to attempt this, at least once in our lifetime. The bare LCD and any reflective papers, etc. are available on Aliexpress.

2) Source the same from a known good donor unit. Very concerned about possible compatibility and of course the honesty of the reseller (ie. Ebay specials). Best if you source a working display from your region so that you will know that it is compatible.

3) Purchase a brand new display assembly with logo from Aliexpress - we do this often. Will be with zero dead pixels; pre-tested; but more expensive. The camera will be new as it is inside the display assembly.

We have used this store (and also XJS on Aliexpress) with success:
https://www.aliexpress.com/item/3302...80007263272_13

Be sure to chat with them to understand that the unit is fully pre-tested with zero dead pixels + with logo.

You should also be able to purchase replacement screens on your local Amazon portal. Then you have the support of Amazon and can return it if you are not happy with the results.

The camera may be defective due to a damaged cable or connector / connector seating. Does your 'About this Macbok' detect the presence of the camera at all ? The detection should be over the I2C bus. Testing with a known good display will allow you to validate the screen and the camera.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

I thought I posted this already. I manage to go in safe mode and install the latest OSX and not luck, it stayed the same.
New finding is that I found that the little cable going from the MB to the display had the power line for the FT CAM broken. I measured and resistance on the display side and seems fine, not shorted to anything else or ground, I tried with another cable from a macbook pro 13 inch which is the same, tested it with the multimeter to make sure it had the same internal connections, but the problem is the same with the display (I could not test the FT Cam) as I could not mount the board because I could not screw the cable connector and it was too lose.
I will try to get a display. But I am also curious if the little board that comes with the display could be the problem as the cables and the panel look fine. I can another of those board from a different computer, no panned connected but does have back light, same main reference different revision (820-00452-A is what I have -4 is the donor board". I found that it has a test point labeled 1V8 which measuring in diode mode (+ to ground) gives 0.15 on the computer I am trying to fix and 0.5 on the donor board. I disconnected the backlight just in case. And on the donor board I measured the pins on the cables that would go to the missing panel and it is not connected to any of them. I the schematic section I asked for the schematic for this board.

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

In the USB section it shows a FT camera but the serial number has a exclamation mark. But well, not it is clear why the FT Cam does not work. I wonder how that happened as it does not look shortcut, but the cable had an obvious bubble on top of that line like it got hot.

[mon2]

Re: 820-01814 No image on LCD and USBC ports acting strange

Can you post a the USB screen view where the camera is detected?

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

Here the camera in USB. Edit, I added picture of the board. The test point on the right with the label 1V8 is the one giving 0.15 in diode mode in the computer I try to fix and 0.5 in the donor.

[mon2]

Re: 820-01814 No image on LCD and USBC ports acting strange

What are the voltage to ground measurements of the following points?

Facetime Camera interface:

I2C_FTCAM_SCL
I2C_FTCAM_SDA

ALS (ambient light sensor):

I2C_ALS_SCL
I2C_ALS_SDA

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

They are all 1.8V. This is with the display disconnected. It is a bit difficult to access with the display connected. I initially tested I2C_CAM_ISOL_SDA and SCL because I thought the CAM ones would be also on that connector and they are also 1.8V

[samolo75]

Re: 820-01814 No image on LCD and USBC ports acting strange

I replaced the flex cable from the MB to the display and now the facetime camera works. The LCD still not working. The USB ports keeps doing weird stuff. I connect the USB hub to it and the HDMI output works, the Ethernet port works, the SD card reader works, but if I connect a mouse it does not work. I had a couple of times where after around 20 min from the computer to being on it started working, and this is what I found from the hardware information on the mac. Apparently the USB 2 hub does not work initially. Please, any ideas?