27" imac and 23" Cinema Display not waking

Discussion in 'iMac' started by bodtwo, Oct 17, 2014.

  1. bodtwo macrumors newbie

    May 24, 2011
    Hi all,

    I've a late 2011 27" imac with an aluminium 23" Cinema Display that's been running fine up until I installed 10.9.5. Since then the external display is not coming back on after the screens have gone to sleep.

    The only way I can get it to work is to pull the power cable from the Cinema Display, plug it back in and when I do that the imac recognises it and it works.

    I've tried a PRAM and SMC reset but the problem persists, I've even installed Yosemite but I get the same issue.

    Any ideas?

    Thanks all.
  2. bodtwo thread starter macrumors newbie

    May 24, 2011
  3. eduardrw macrumors 6502

    May 20, 2013
    Won't help you debugging your problem but:
    I run a 27' late 2009 iMac with 30" Cinema display - no problems with wake ups at all.
    Maybe time for a clean install.

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