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The March 2015 update of Apple's 13" MacBook Pro Retina Display, model A1502, features fifth-generation Intel Core i5 and i7 processors and introduces the Force Touch trackpad.

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A1502 LCD no video on wakeup, backlight is on

I am trying to fix an early 2015 13" MBP.

Got it working (mostly) except on wake from sleep (or when rebooting during an install) I lose video output on the LCD. Backlight is on (verified by turning bringhtness all the way up, I get a light vertical display output from second lvds channel)

If I don't close the clamshell, use screen saver with "never sleep" timeout, it works fine (except needing hard power down if I update OS)

Unfortunately due to cats who love walking on keyboards, I need to close the lid.

I have tried:

  1. SMC and P/N VRAM reset
  2. unplug/replug battery (battery is "normal")
  3. safe mode
  4. booting external SSD (same problem)
  5. reinstalling OS
  6. googling many hours for answers

I suspect something with LCD voltage rails coming out of sleep, but I need to find the schematics and board view to check.

I will try an external hdmi monitor, which I suspect will work, but that does not help with getting sleep working.

Any/all help much appreciated,

Bill

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External HDMI monitor works when clamshell is opened up.

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Apple -> Restart reboots to blank LCD, external monitor works fine.

Apple -> Shutdown, then power on, LCD and monitor come up fine

I suppose I could disconnect the lid closed sensor, but that is less than ideal.

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I suspect there must be an LVDS (eDP?) buffer that is being enabled by the SMC on cold startup, that is disabled when the lid is closed, and not being re-enabled properly by the SMC when waking up on lid opening.

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@danj - You probably know the problem...

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@mikronauts - Let’s back up here a bit… What happened on your repair journey? You talk about your cat loves walking across your computer is it possible it marked your system?

As far as your video retina systems use iDP signaling while the cable is similar to the older LVDS cable the signals are very different like the older analog TV and our current digital TV signaling both use an antenna so we can’t assume the conduit is the same just like how water and gas both use pipes.

As far as what the external display uses. It uses either DP or Thunderbolt connection (the video in both is DP)

The logic board uses a MUX to spilt out the video to the internal and Thunderbolt ports. If you are getting a good external image via both TB ports then we know the issue is strictly within the internal displays path if it doesn’t offer a good image.

As far as wake/sleep that is a different circuit which would need to be independently tested and repaired. While from the use perspective they do fit hand to glove they are not one in the same.

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Hi Dan,

I got the laptop from an e-cycler.

Powered up fine, started charging the battery. Eventually I got a blinking folder.

SSD could not be detected from USB installer, it had some "gunk" on it. I replaced it with a 500GB Apple SSD.

During install, I lost video when the installer rebooted. Hard power off / power on successfully completed the install.

Mousey (the cat that loves keyboard surfing and sleeping on keyboards) did not water the keyboard :) I only let her sleep on desktop keyboards.

Thank you, I will read up on iDP, have not run into it before.

I tried two external monitors, a mini dp to displayport with a 1080p HP E231, and a mini dp to hdmi with an asus 4k monitor.

Both worked, the Asus ended up going to the "static noise" screen which I believe signals an hdcp issue. I previously tried hdmi to hdmi, which worked.

The internal display path for the LCD is fine from a cold boot, as long as I stop the laptop from sleeping, and I don't do any warm boots.

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@mikronauts - OK, so we should run the onboard diagnostics to see if any errors pop. Restart your system and press the D key to enter. Let’s know what you got.

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It would only display from a cold boot, and said:

No Issues Found.

Reference code ADP000

I even tried to attach an external monitor in mirror mode, still no joy on a warm reboot.

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Interesting update.

After the diagnostic run, I chose "Restart" (I still had an external monitor connected)

After the restart, the LCD came on.

I closed the lid, and when I opened it, the LCD came on (along with external monitor)

Then I unplugged the montor, closed the lid, opened it... lcd did NOT come on.

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I plugged the monitor back in, turned the laptop on.

With a monitor connected, I can close the lid, open it back, and I get the LCD display and monitor behaving correctly.

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Final update:

I checked the schematic, there is no mux between the eDP LCD and the i5 SOC on this model.

I downloaded and read the SOC datasheet, thinking perhaps there was an external voltage regulation issue on wakeup - but the video core voltage regulation is in the SOC, not external.

I bit the bullet, and bought a replacement logic board on eBay (got one with 16GB) and just finished installing and testing it.

WORKS FINE

Therefore I must conclude the issue was within the SOC, something to do with changing power states.

I can use the defective board with an external monitor, or perhaps I'll replace the SOC in the future.

I appreciate all the helpful suggestions I received!

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William Henning crwdns2934231:0crwdne2934231:0
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