A1260 Black Display

[SecretSquirrel]

Morning all! I have a problem which I hope someone else has seen before. I recently acquired a mint condition MBP15 A1260 which I knew had a problem but didn't know what. It turned out that the problem was that it would boot fine using an external display but the internal display would stay black
Thinking this was the old graphics chip problem I dug out a spare working board (at least I thought it was working) swapped them over - and have exactly the same problem. Thinking I couldn't have 2 faulty boards I swapped in a spare display but the problem remains. I was aware of the symptoms of a failed graphics chip being not booting, fans blaring, sleep light half on etc but I don't remember reading anything about a failed graphics chip still working with an external display! Has anyone seen this before? Maybe @dosdude1 ? Thanks for any info you might have!

 

[Amethyst1]

Can you see something on the display if you shine a very bright flashlight against it?

The cable that connects the display to the board may be faulty.

 

[bobesch]

Can you see something on the display if you shine a very bright flashlight against it?

The cable that connects the display to the board may be faulty.

Yep. A replacement display-assembly might be the fix.

 

[SecretSquirrel]

Sorry, if I didn't explain it clearly - I swapped the entire lid with display and cables for a spare one. So unless both cables are broken... Am I right in thinking that a graphics chip failure would affect the external display too? When the laptop boots up, you can see the display change from blank to actual black so the led backlight is working - it's just that there's nothing but black on the screen.

 

[DeltaMac]

The video chip is on the logic board. You could try swapping out the left I/O board. The backlight connects through that, so it's a possible fix. After that, it's the logic board.

 

[bobesch]

When the laptop boots up, you can see the display change from blank to actual black so the led backlight is working - it's just that there's nothing but black on the screen.

So you first see a display that has backlight? - At what point does it turn black?
And an external display through DVI-out still does work fine?
The next thing I can think about is a faulty socket for the display-cable ...

 

[SecretSquirrel]

It turns black at the same time as the login screen background appears on the external monitor. What gets me is I'm seeing the same fault on two different boards with two different displays and two sets of cables whatever combination I try. Currently looking for yet another board...

 

[B S Magnet]

It turns black at the same time as the login screen background appears on the external monitor. What gets me is I'm seeing the same fault on two different boards with two different displays and two sets of cables whatever combination I try. Currently looking for yet another board...

I’ll go on a limb here and ask whether you have, without an external display connected, performed an NVRAM/PRAM reset and/or performed an SMC reset. The symptoms you’re describing hints that the MBP could be entering “clamshell mode” even when there isn’t an external display connected.

Going out even more on a limb, have you tried to boot from an (external) drive with a different installation of OS X? By the sound of it, you’ve changed both board and display, but not the internal HDD. I don’t know its history, but it’s possible there’s a plist parameter which kicks into “clamshell mode” (using external display only and disabling the laptop display) despite the absence here of an external display.

If I were to hazard a guess, the plist toggling the “clamshell mode” flag may have inadvertently been given read-execute-only permissions (such as 555) whilst used by its previous owner, preventing even the system from overwriting the flag for clamshell mode. If you can, try booting from an external drive or from an OS X install disc, open Disk Utility, and run “Repair Permissions” on your internal HDD. I’d be curious to learn whether the ownership/permissions on plist files might be the culprit here.

 

[bobesch]

I’ll go on a limb here and ask whether you have, without an external display connected, performed an NVRAM/PRAM reset and/or performed an SMC reset. The symptoms you’re describing hints that the MBP could be entering “clamshell mode” even when there isn’t an external display connected.

Going out even more on a limb, have you tried to boot from an (external) drive with a different installation of OS X? By the sound of it, you’ve changed both board and display, but not the internal HDD. I don’t know its history, but it’s possible there’s a plist parameter which kicks into “clamshell mode” (using external display only and disabling the laptop display) despite the absence here of an external display.

If I were to hazard a guess, the plist toggling the “clamshell mode” flag may have inadvertently been given read-execute-only permissions (such as 555) whilst used by its previous owner, preventing even the system from overwriting the flag for clamshell mode. If you can, try booting from an external drive or from an OS X install disc, open Disk Utility, and run “Repair Permissions” on your internal HDD. I’d be curious to learn whether the ownership/permissions on plist files might be the culprit here.

How about starting with NVRAM/PRAM reset and booting into TargetDiskMode without attached external monitor just to see, if the internal display behaves normal then?
Would ClamshellMode have an effect on the display when the MBP is in TDM?

 

[SecretSquirrel]

I’ll go on a limb here and ask whether you have, without an external display connected, performed an NVRAM/PRAM reset and/or performed an SMC reset. The symptoms you’re describing hints that the MBP could be entering “clamshell mode” even when there isn’t an external display connected.

Going out even more on a limb, have you tried to boot from an (external) drive with a different installation of OS X? By the sound of it, you’ve changed both board and display, but not the internal HDD. I don’t know its history, but it’s possible there’s a plist parameter which kicks into “clamshell mode” (using external display only and disabling the laptop display) despite the absence here of an external display.

If I were to hazard a guess, the plist toggling the “clamshell mode” flag may have inadvertently been given read-execute-only permissions (such as 555) whilst used by its previous owner, preventing even the system from overwriting the flag for clamshell mode. If you can, try booting from an external drive or from an OS X install disc, open Disk Utility, and run “Repair Permissions” on your internal HDD. I’d be curious to learn whether the ownership/permissions on plist files might be the culprit here.

Thanks for that suggestion @B S Magnet - I'll try it when I get a chance over the next few days and let you know what I find.

 

[SecretSquirrel]

Tried all suggestions but sadly no success. It must be the board. Thanks anyway.

 

[bobesch]

Tried all suggestions but sadly no success. It must be the board. Thanks anyway.

Well, as @DeltaMac already mentioned, maybe then the inverter-board or the plug/socket...

MacBook Pro 15" Core 2 Duo Models A1226 and A1260 Left I/O Board Replacement

Provides power to the machine and includes all ports on the left side of the machine.

de.ifixit.com

I'd look for a cheap defective A1260 with the typical GPU-failure (or just the left-i/o-board) for replacemet of the i/o-board.
Cannot imagine, that the logicboard is causing the problem, if an external Display does work fine.

 

[SecretSquirrel]

Sorry it's been a while since you all posted suggestions - life takes over, you know what I mean, I'm sure. I've been rebuilding Macs, Powerbooks, Macbooks and Macbook Pros for 12 years and I've never seen a puzzle like this. To recap, this is the story so far...

I have a very clean A1260 MBP, perfect condition except the internal display doesn't show anything although external display works fine. To date, I've replaced the logic board (twice), the left IO board and the whole display panel (cables and all). There's still no internal display. All that's left of the original machine is the bottom case, the top case and the keyboard. I've disconnected everything not needed to boot ( isight, WiFi, super drive) but no change. Because the machine is in bits, I can see the LED backlight is working fine - it's like it's deliberately displaying black.

I'm completely stumped. On the other hand, I now have enough bits to build another working machine! 😁

 

[SecretSquirrel]

After a lot of head scratching, I'm now wondering if the sleep sensor is faulty and the laptop is thinking the lid is closed when it boots up. Will try to find a cheap replacement top case to carry out some more testing...

 

[Needleroozer]

After a lot of head scratching, I'm now wondering if the sleep sensor is faulty and the laptop is thinking the lid is closed when it boots up. Will try to find a cheap replacement top case to carry out some more testing...

It looks like ioreg can tell you if the laptop thinks the lid is closed:

How to Check if Macbook Lid is closed via Terminal?

I'm running OS X 10.8 (Mountain Lion). I was wondering if there was a terminal command to check if the macbook pro's lid is currently closed. If I used grep, what would I be looking for exactly, and

stackoverflow.com

ioreg -r -k AppleClamshellState -d 4 | grep AppleClamshellState  | head -1

“No” means it’s open; “Yes” means it’s closed. This worked on my A1260 (running Mavericks) and a 2014 13” rMBP (Mojave).

If the laptop thinks its lid is shut, you could check the sensor cable (highlighted in yellow in the attached picture) and see if it traces back to the main top case connector without trouble.

I couldn’t find a direct match for the Hall effect sensor in the top case (SOT-23 with code 12E) online, but it looks like most SOT-23 Hall effect sensors have a pretty standard pinout with an active-low output on pin 2.
The schematics I found for the A1260 online show that the sensor line has a 100K pullup to PP3V3_S5_SMC, which means that unplugging the sensor’s connector on the top case should tie that line high, thus telling the SMC that the lid is not closed.

I haven’t tried unplugging the sensor on my A1260 because it’s a bit of a nuisance to remove the top case, but I think it is definitely worth a shot if the sensor thinks it’s tripped even when the lid is open.

 

[SecretSquirrel]

Thanks - I'll give it a go!

 

[SecretSquirrel]

Unfortunately, a different top case made no difference. Having replaced the logic board (twice), the LH I/O board, the display panel, the LVDS cable and the top case I was left with little else to try. By this time I had the whole machine completely dismantled so in disgust threw the whole lot in a box and left it on a shelf for 3 months. Recently, having calmed down, I fished it all our again and re - checked everything again but still no luck. Reluctantly admitted defeat and went for a look on ebay to see if there was anything interesting - and bagged two in working condition for a total of £70. They need a bit of work but I have a large stock of parts from this saga. Will post details later.