MacBook Pro Retina 820-00138 Black Screen

[ACS-Repair]

I have an unusual problem with a 2015 MacBook Pro 820-00138 and I'm curious to see if anyone else has seen this problem. It has the integrated Intel Iris Pro graphics.
When I turn it on, the screen is black with no backlight. If I connect an external Thunderbolt Display, I will see the extended display on that screen. If I tell the computer to mirror the displays, the Thunderbolt Display will also go black. If I disconnect the internal screen and connect only the Thunderbolt Display, I will have the main screen displayed there. I have tested the screen on another computer and it is known to be good.
Is it possible for a part of the GPU to fail so that the primary display buffer would remain black?

[Stephen]

Re: MacBook Pro Retina 820-00138 Black Screen

If you tested the LCD on another computer and know for sure it works and turns on, I would test voltage on the LVDS connection and see if you are getting voltage there. Also test your Backlight fuse as well. if the backlight fuse is blown there is most likely a short on the board. Again your GPU is most likely fine on this model, these models usually dont have faulty GPUS in this year.

[ACS-Repair]

Re: MacBook Pro Retina 820-00138 Black Screen

Hi Steven, thanks for your input, it's much appreciated. I believe I have the answer to this after doing a bit of research. Unfortunately I didn't mention that the known working screen was tested on a 2014 A1398, and that was the reason it didn't work on the 2015. I had bought a 2014 A1398 complete and I thought that the 2014 and 2015 screens were interchangeable, but my research tells me that is not the case. So it looks like even though the screen was recognized on the 2015, it wasn't going to work. It also explains why the screen buffer was black. It's another learning experience! Now I'm looking for a good deal on a 2015 screen.

[Stephen]

Re: MacBook Pro Retina 820-00138 Black Screen

Of course! Mid 2015 LCD models are only for MID 2015 models.

A1398 LCD models go like this:

Mid 2012/ Early 2013 - Use the same LCD in this year
Late 2013/ Mid 2014 - Use the same lcd in this year
Mid 2015 - Only one type of LCD in this year.

Although the LCDs are identical in shape and size they are not the same. There are 3 types of Retina LCD models. This goes for 13" models as well.

Also 15" Models in Touchbar go as follows:

A1707
2016/2017 Use the same lcd

A1990 Uses a different LCD, and has true tone for the T2 Chip
which is a 2018/2019 LCD

These LCDs can look the same but have different part numbers on them. If you use an LCD that is not on a 2018 and from a 2017, the LCD will turn on but it will disable your webcam, true tone and keyboard backlight. And once you do that, you have to wipe your SSD drive and reinstall all your data with the proper LCD because it will wipe the serial off of the T2 LCD.

[ACS-Repair]

Re: MacBook Pro Retina 820-00138 Black Screen

Thanks for that explanation Stephen.
I have just received a used/broken screen that is supposed to be for a 2015 A1398. I'm not convinced that it is working properly or may not be a 2015. There is a crack on the right side that affect only 3/4 inch of the right side. Most of the screen appears to be OK.
What I find is that when the screen comes up, the backlight comes on and the screen becomes active, but the display remains black. I have it connected to an external Thunderbolt Display to monitor everything.
It takes 13 seconds for the internal display to become active. This is all while the boot screen is active on the Thunderbolt Display but still on the Apple logo and progress bar. Graphics are a bit jerky, definitely not the same as when there is no internal display connected. The delay is trying to tell me something... on other MacBooks the Thunderbolt Display won't come up until after I login. If the screens are mirrored, The Thunderbolt Display will become active at the login screen.
As a reference, this is the first time that an internal display has been connected to this computer. I'm at a loss to determine if this is a screen issue or a computer issue. I would appreciate it if anyone who has had a similar experience would comment.

[ACS-Repair]

Re: MacBook Pro Retina 820-00138 Black Screen

For clarification, when I say the screen comes up, I mean the backlight comes up. Brightness control works as it should. The pixels on the LCD appear to be working.

[ACS-Repair]

Re: MacBook Pro Retina 820-00138 Black Screen

Based on piernov's recommendation from another thread I have measured the voltages on pin 5 (3.3v), pin 9 (3.3v), and pin 28 (5.1v). These voltages are present at startup and last through for at least 1 minute. There is never picture on the screen and no backlight in stand-alone config (i.e. no external display). I have confirmed that this is a 2015 screen.
I'm trying to determine if this is a logic board issue or something to do with the screen. I don't have another screen unfortunately.

[ACS-Repair]

Re: MacBook Pro Retina 820-00138 Black Screen

I tried another screen that I bought on ebay (broken) with much the same results. I get 1.65v at the chime on the LCD_HPD line even though there is no display or backlight until the login prompt. I thought that maybe this was related to the lid sensor but I put a magnet over it and got the expected response. I'm certainly not going to invest anymore into this until I can better understand the LCD startup sequence and determine what is missing or why the delay.

[ACS-Repair]

Re: MacBook Pro Retina 820-00138 Black Screen

Just to close this off... it's been a while and I resolved this after finding a broken dual inductor on one of the data lines to the screen. It seems if any of these lines are broken the screen will not display anything, which makes sense. Thank you to all that participated.

[Simplebeans]

Re: MacBook Pro Retina 820-00138 Black Screen

Just to close this off... it's been a while and I resolved this after finding a broken dual inductor on one of the data lines to the screen. It seems if any of these lines are broken the screen will not display anything, which makes sense. Thank you to all that participated.

Well done ACS-Repair!