MB can't detect own display after using external

Hi andmic,

Have you tried resetting the PRAM? Hold Command + Option + P + R on startup until it gives you a second POST chime. I had the same issue happen with my 13" MacBook Pro last week and this resolved the issue.

Hi andmic,

Interesting... so let's rehash:

1.) You've reset the PRAM. Let's try it again, this time hold the key combination down until you hear at least three POST chimes. Probably won't change anything but it can't hurt.

2.) You indicated that you disconnected the battery, did you perform an SMC reset? That is, with the battery removed and no connected power you hold the power down for 8-10 seconds and then reconnect everything.

3.) If you put the OS X Installation DVD that came with your computer into the machine and startup holding the "C" key, anything? What if you try starting up holding the "Option" key, anything?

I'd say, if after those three steps we're still unsuccessful in getting video on the built-in display but successful in getting video on the external monitor it's time to bring it into an Apple Authorized Service Provider or an Apple Retail Store. The behavior you're experiencing is not normal.

By all means follow the suggestions above.

I would also check the adapter and the video port on the Macbook. You may need a strong light and a magnifying glass. Look for bent pins especially in the video port.

I mean the socket on the MacBook that you plug the adapter into.

It is a very scary port. A poster on this forum had a problem with his video output and the Apple Tech found a bent pin in the port socket.

You have that video port that may affect both screens. A pin could be bent and shorting whatever is common to both screens.

A little far fetched maybe, but worth eliminating. An Apple tech may have to deal with it - with the usual "needs new circuit board" panacea.

I have had precisely the same problem. After two years of using this setup, suddenly the MBP cannot detect the internal display.
- The first time it occurred (earlier this week), I restarted the MacBook while holding down the R key, in order to reset the screen configurations.
That worked until the next time I unplugged the external monitor.

I have:
- reset PRAM (multiple times, three chimes)
- pulled the power and battery and performed an SMC reset.
- pulled all the peripherals and booted up using the OS X installation DVD

This was the interesting part!! I was able to boot up the OS X installation. The internal display was just fine. No problems with it whatsoever. I repaired permissions, and I verified the disk.

When I rebooted from the HD, the internal screen went black after the 'wagon wheel' stopped spinning under the Apple logo (as it always does on a boot).

I then decided to blow away the files
~/Library/Preferences/ByHost/com.apple.preference.displays.<some number>.plist
~/Library/Preferences/ByHost/com.apple.windowserver.<some number>.plist

This was what I found in the following thread:
http://discussions.apple.com/message.jspa?messageID=9344967

The System booted back up with the internal display recognized !!!.... until, I did a "detect displays", at which point the screen went black again!!!

I am now back where this whole thing started. I have an appointment at the Genius Bar tomorrow.

1) The fact that when booting from the DVD works without problem leads me to think this is an all-software issue
2) I'd like to figure out *** has borked the system. I note that I am unable to use teleport (a way of sharing a single keyboard & mouse) across two Macs on a LAN.

Because I'm about to leave on travel and HAVE to have a functioning MacBook, I'm contemplating doing a clean install, reinstalling software and then pulling back my work files from TimeMachine. (Oh joy.)

rhm2k wrote:
I have had precisely the same problem. After two years of using this setup, suddenly the MBP cannot detect the internal display.
- The first time it occurred (earlier this week), I restarted the MacBook while holding down the R key, in order to reset the screen configurations.
That worked until the next time I unplugged the external monitor.

I have:
- reset PRAM (multiple times, three chimes)
- pulled the power and battery and performed an SMC reset.
- pulled all the peripherals and booted up using the OS X installation DVD

This was the interesting part!! I was able to boot up the OS X installation. The internal display was just fine. No problems with it whatsoever. I repaired permissions, and I verified the disk.

When I rebooted from the HD, the internal screen went black after the 'wagon wheel' stopped spinning under the Apple logo (as it always does on a boot).

I then decided to blow away the files
~/Library/Preferences/ByHost/com.apple.preference.displays.<some number>.plist
~/Library/Preferences/ByHost/com.apple.windowserver.<some number>.plist

This was what I found in the following thread:
http://discussions.apple.com/message.jspa?messageID=9344967

The System booted back up with the internal display recognized !!!.... until, I did a "detect displays", at which point the screen went black again!!!

I am now back where this whole thing started. I have an appointment at the Genius Bar tomorrow.

1) The fact that when booting from the DVD works without problem leads me to think this is an all-software issue
2) I'd like to figure out *** has borked the system. I note that I am unable to use teleport (a way of sharing a single keyboard & mouse) across two Macs on a LAN.

Because I'm about to leave on travel and HAVE to have a functioning MacBook, I'm contemplating doing a clean install, reinstalling software and then pulling back my work files from TimeMachine. (Oh joy.)

Problem (apparently) resolved!!

From the thread noted above, I found this:

The fix for this was also relatively simple. After a bit of googling, I stumbled upon a thread of folks having a very similar issue. The fix was to plug the laptop into a completely different monitor. Lo and behold, wouldn't you know it worked! I powered the laptop off, plugged it into a different monitor, powered it on and then immediately closed the lid. The external monitor then comes to life as the sole display. I then shutdown again, and reconnected the actual display I was trying to use and did the same thing--plug into monitor, power on, then immediately close the lid. Worked perfectly!

And... sure enough. I've plugged into a different external monitor at work, and... the internal display is now active (as is the external display). Detect displays seems to work.

So... solution here seems to be to remove the preference files, restart and plug into at least TWO different external monitors.

Wierd.

= RHM2k