External Display - What's Wrong?

[Melodeath]

I have a mid-2010 MBP and a 20" Samsung external monitor. I have a miniDisplay port to DVI adapter which I use to connect to the external display. Up until about the end of 2010, I used the external display and everything was great. I unplugged the cable whenever I needed to be mobile, and the screen switched to the laptop screen. Anytime I wanted to use the display, I just plugged the miniDisplay plug back in and it shot back to the external monitor.

I then stopped using the monitor and just used the laptop screen full time.

Now, I'm trying to use the external display again, but it's not working. When I plug the display plug in, the MBP screen goes light blue for a second, like it's switching to the video card, but the external display doesn't detect anything.

I got it to work once, by closing the lid of the MBP, then opening it and moving the mouse, which somehow shot the signal to the external display, but I haven't been able to replicate this. What am i doing wrong? It use to be just plug n play, and now it's not working and seems like I have to do something special.

OSX 10.6.8 (I was on an earlier version of 10.6 when it worked perfectly)

 

[upaymeifixit]

Sounds like it is having a problem extending the desktop (this would explain why it worked in clamshell mode. I am going to guess it has something to do with 10.6.8.

Try booting up in safe mode (hold shift at startup) to see if it's a software conflict. Post the results.

 

[Melodeath]

Well, I put it in clamshell mode, the comp went to sleep (and all USB devices lost power), then I hit spacebar on an external keyboard. The comp woke up but went back to sleep bc it was still in clamshell. I then gave up and opened the computer up, put fingers on the trackpad, then external display worked. IIRC

So I had both displays going at once, which is how I always had it.

 

[upaymeifixit]

So... it's working now?

 

[Melodeath]

No no - I was just going into depth regarding how I got it working the one time since I started having this issue.

 

[Melodeath]

Update: I disabled gfxStatus from the Login items. Didn't help.

I restarted with the miniDisplay hooked up already. Didn't help. Ughh

 

[upaymeifixit]

Have you tried starting in safe mode?

 

[Melodeath]

With the recent video update for mid-2010 MBPs, I decided to try my external monitor again, but I am again having no luck.

I tried various resets with an AppleCare tech back in July, and it was concluded that 10.6.8 simply "broke compatibility" with my monitor - is that even possible? The monitor is 4 years old - doesn't seem old for a monitor.

 

[Melodeath]

Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A405 Safari/7534.48.3)

I just tried another a totally different monitor. Plugged into DVI. Plugged into MBP. Switch monitor to digital input. Monitor immediately goes to power saver mode. Any ideas? Is my miniDisplay port busted?

 

[Melodeath]

It didn't work when I booted into Windows 7, either, so it can't be a software issue

 

[unixperience]

if you have another computer try that. There is a chance your minidp-dvi is broken. they do die. Fortunately they can be bought on amazon for about 8 bucks(including shipping). Just see if you can try somo other input to the screen, butDONT use your adapter. theres a good chance its the adapter
additionally, when you have it plugged in and the screen goes blue you can check in system profiler under displays, see what it says

 

[Melodeath]

Thanks! Your idea inspired me to ask around and I was able to borrow a miniDisplay>VGA adapter, and this worked with my monitor. So it looks like the culprit is not my port or the software, but the miniDisplay>DVI adapter. I wonder if this cheap one from Amazon has a warranty haha

When I chose to mirror the displays, my MBP viewable area became a square instead of the usual 15" widescreen, but maybe that's normal for VGA?