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  1. #1

    geoffstgermaine's Avatar
    Member Since
    Aug 30, 2006
    Winnipeg, MB
    24" iMac
    Display problem when disconnecting iMac from TV
    I did a search here and elsewhere and haven't found this problem mentioned anywhere.

    I have a 1st Gen white 24" iMac with the Nvidia 7600. Occassionally when disconnecting it from my television, I get severe display problems, which is best described as the screen appearing as a bunch of blocks with horizontal lines matching the colours of the current background.

    The connection I have is from the iMac to my Onkyo receiver via a mini-DVI to DVI connector and a DVI to HDMI adapter with an HDMI cable connecting to the Onkyo receiver. The receiver is connected to the TV with another HDMI cable.

    Like I said, the problem is only intermittent and I would say it happens approximately 15-20% of the time. In order to correct the problem I have to reboot the computer... I've tried switching back to the iMac output on the receiver or turning the receiver back on (both cases can cause the display problem) and it never goes back to normal. In about 30% of the other times switching the display the iMac goes into mirrored mode (I don't use mirrored normally, I use the TV as the secondary display). I've also never had the problem when connecting to the iMac, only when disconnecting.

    Has anyone seen anything like this before or know of anything to try to stop this from happening? It's mostly just an annoyance having to restart the computer about 20% of the time when disconnecting the video out to the TV.


  2. #2

    chscag's Avatar
    Member Since
    Jan 23, 2008
    Keller, Texas
    2017 27" iMac, 10.5" iPad Pro, iPhone 6s+, iPhone 7+, Numerous iPods, High Sierra
    With all the connections you currently have it's hard to say where the signal is being disrupted. (I believe that's what is happening - causing the distortion.)

    As a test, hook your iMac direct to the TV instead of going through the Onkyo receiver.


  3. #3

    bobtomay's Avatar
    Member Since
    Dec 22, 2006
    Texas, where else?
    15" MBP '06 2.33 C2D 4GB 10.7; 13" MBA '14 1.8 i7 8GB 10.11; 21" iMac '13 2.9 i5 8GB 10.11; 6S
    First off, every technical sheet you'll find from any manufacturer (whether TV or computer) will tell you to turn off your equipment when connecting and/or disconnecting a display to a computer, because of issues like this.

    Having said that, I think a lot of us (myself included) do the same thing. But, I doubt very seriously, that you'll find a fix for it.
    I cannot be held responsible for the things that come out of my mouth.
    In the Windows world, most everything folks don't understand is called a virus.

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