27" iMac Connected to HDTV Blue Screen

Discussion in 'Mac Basics and Help' started by Paulyboy, Jun 6, 2010.

  1. Paulyboy macrumors 6502

    Joined:
    Jan 26, 2007
    #1
    I have a 27" iMac and an LG 47" 1080p HDTV. I just bought the Griffin Video Display Converter, which is certified by Apple to pass both video and audio from the mini display port on the late 2009 iMacs. It works perfectly in that regard but there is an issue.

    Whenever somebody turns on the HDTV the iMac's screen flickers the color blue on and off, sometimes staying that way permanently. Permanently the color blue that is. The only way to get out of it is to turn the iMac off and then back on (restarting it).

    I have the “Mirror Displays” checkbox checked in the “Display Preferences”. When I uncheck that box it treats the connected HDTV as an extension to the iMac display, whether the HDTV is on or off, which makes my cursor disappear off one side of the screen. This is why I leave mirroring on.

    I've actually seen this problem with other adapters and even another iMac (a late 2006 one). Although usually in those other cases the screen would just flicker blue on and off for about a minute after turning on the connected HDTV. Only on rare occasions with the screen stay stuck on blue like it's doing now almost every time.

    I'm assuming there must be some sort of solution for this or something I'm not doing right as this adapter is certified by Apple for these iMacs. Perhaps some sort of setting on the iMac or the TV itself? Any help would be greatly appreciated.

    -PN
     
  2. spinnerlys Guest

    spinnerlys

    Joined:
    Sep 7, 2008
    Location:
    forlod bygningen
    #2
    As the HDTV only has a resolution of 1920 x 1080 pixel, and the 27" iMac has a resolution of 2560 x 1440, MIRROR DISPLAYS forces the iMac's display to reduce its resolution to 1920 x 1080, unless it doesn't, as you haven't reported any such issue.

    Have you tried to just pull the adapter out of the Mac while the HDTV is not connected?

    Btw, the blue screen is just a sign of changing resolutions.

    Have you tried this?
    http://support.apple.com/kb/ht1379
    http://support.apple.com/kb/HT3964
     
  3. Paulyboy thread starter macrumors 6502

    Joined:
    Jan 26, 2007
    #3
    Thanks for the suggestions. I will try these things when I get a chance. I should note that I usually have my iMac set to 1600 x 900 resolution, which the HDTV should support as well.

    I'll report back my findings as soon as I get a chance to try your suggestions. Thanks again. :)

    -PN
     
  4. spinnerlys Guest

    spinnerlys

    Joined:
    Sep 7, 2008
    Location:
    forlod bygningen
    #4
    You have that Mac set to a resolution roughly 40% percent of its original resolution? That must look abysmal.
     
  5. Paulyboy thread starter macrumors 6502

    Joined:
    Jan 26, 2007
    #5
    Looks fine to me. My eyes aren't what they use to be, and I don't sit really close to the iMac, so the native resolution just makes everything so tiny.

    -PN
     
  6. Paulyboy thread starter macrumors 6502

    Joined:
    Jan 26, 2007
    #6
    Okay the problem appears to be solved. I switched the resolution on my 27 inch iMac to 1980 x 1080 and now switching the HDTV on, or doing anything with it, doesn't cause a permanent blue screen. It only flickers briefly – the same kind of flicker you see when switching resolutions.

    Being that 1980 x 1080 is the same resolution as an HDTV maybe that has something to do with it? In any case I will just start using my iMac regularly in the 1980 x 1080 resolution, as opposed to the 1600 x 900 resolution. It's not as tiny as I thought and I'm already getting used to it. I guess this way people won't make fun of me as much now either. :)

    -PN
     
  7. Kevo82 macrumors newbie

    Joined:
    May 2, 2010
    #7
    When you use 1920x1080 on the 27" iMac, the image it's full, or you get black bars? I guess that you use mirror displays and overscan options.

    I want to know if a 27" iMac would be better than a 21.5" iMac for connecting to the TV, because the native resolution of the 21.5" iMac it's exactly the same as the 1080p HD TV (1920x1080)
     
  8. Paulyboy thread starter macrumors 6502

    Joined:
    Jan 26, 2007
    #8
    I haven't connected my iMac and HDTV like that in awhile now but when I did there were no black bars. On a 21.5" iMac you could use 1280x720 (720p) perhaps?

    With the very soon to be released Mountain Lion having AirPlay to Apple TV mirroring built in it seems like picking up an Apple TV for $99 would be the better way to accomplish this now.

    -PN
     
  9. Kevo82 macrumors newbie

    Joined:
    May 2, 2010
    #9
    No, if you connect the 21.5" iMac, both displays will work normal because both have the same resolution.

    The 27" iMac has a higher resolution, and I wanted to know if it's using a lower resolution in full display or with bars. Anyway I think that you have to select 1920x1080 in the iMac display settings


    Do you think that ANY program will work to mirror display to the AppleTV, or just from iTunes?

    Because I use XBMC for local movies and Safari for online TV shows. I don't use iTunes for movies, because all my movies are mkv blu ray rips.

    I had a 720p jailbroken AppleTV with XBMC but I wasn't pleased with the freezing during a 1080p movie (via cat6).
     
  10. Paulyboy thread starter macrumors 6502

    Joined:
    Jan 26, 2007
    #10
    I think it's suppose to mirror ANYTHING on your Mac (audio and video) but I don't know for sure.

    -PN
     
  11. Kevo82 macrumors newbie

    Joined:
    May 2, 2010
    #11
    It would. Perfect but I doubt that. I think it will work just like AirPlay, from iTunes.

    With iOS also works from YouTube and a few others but with OS X only from iTunes. This would mean that I have to encode all my movies to mp4 and I don't want that.

    I have a HDMI in the wall from one room to another so it will be OK. Apple TV has some issues that you don't want to see when watching a movie.
     

Share This Page