Gatepark
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Q: WEIRD SCREEN PROBLEM

Hi,

 

I'm new to the forum and I'm helping my son-in-law with a display problem on a 2006 iMac G5 a1195 Core 2 Duo.

 

The screen is receiving power (i.e. the lcd backlights are illuminating the panel so the inverter seems to be working) but there is no wallpaper or icons displayed.

 

I've attached an external monitor and managed to mirror the main screen onto it. It displays and the iMac functions correctly in every regard. This makes me think that the main logic board and graphics chip are working OK.

 

I've attached a spare lcd (appropriate model and specification) but that is blank also.

 

I intend to check the lcdv(?) cable when the replacement arrives but if that fails I think I'm out of ideas.

 

Do any of you trouble shooters have any other suggestions?

iMac, Mac OS X (10.5.8), G5 a1195 Core 2 Duo

Posted on Nov 20, 2014 1:25 PM

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Gatepark

Q: WEIRD SCREEN PROBLEM

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  • by Gatepark,

    Gatepark Gatepark Nov 25, 2014 2:52 AM in response to Gatepark
    Level 1 (0 points)
    Nov 25, 2014 2:52 AM in response to Gatepark

    Update: I've replaced the screen cable and still no joy?

     

    Logic board next, unless anyone has any brighter ideas please?

  • by Don Mclellan,

    Don Mclellan Don Mclellan Nov 25, 2014 4:54 AM in response to Gatepark
    Level 1 (15 points)
    Nov 25, 2014 4:54 AM in response to Gatepark

    I may not be much help but you have likely tried the display/monitor settings a few times. Seems to me I also had an issue with a monitor on a similar Mac & restarting making sure the "1" is always the main display & "2" is the added display.  This finally worked but I had problems related to the added display. 

     

    I made the mistake of using the larger (added) display as the main and it failed on me leaving me with a 3 aspirin headache.  In my case I'm sure there was a work around but I could not research since my Mac wanted the primary display, which of course failed.  I borrowed another display to restore the 1 / Main as the builtin.

     

    Mactracker says:

    GRAPHICS

    Graphics CardIntel Graphics Media Accelerator (GMA) 950
    Graphics Memory64 MB DDR2 (shared with main memory, minimum memory usage is 80 MB)
    Display Connection1 - Mini-DVI (DVI, VGA, Composite and S-video with adapter)
    Display Modes

    Dual display extended and video mirroring

  • by Gatepark,

    Gatepark Gatepark Nov 25, 2014 8:46 AM in response to Don Mclellan
    Level 1 (0 points)
    Nov 25, 2014 8:46 AM in response to Don Mclellan

    Hi Don,

     

    Thanks for your reply.

     

    The external monitor is a VGA 1024x768 lcd. And, like you (I suspect) trying to get the Mac to mirror to it is difficult without a functioning main screen. However, I managed by using the VoiceOver (Cmd F5) function to help me navigate (blind!) to the Display window and activate mirroring.

     

    Having reached that stage I've used Gather Windows to pull both display setting pop-up windows onto the external monitor.

     

    I've tried everything I can think of from here. For example, when I change the resolution both displays dim and then redisplay. However, no matter what resolution I choose, the main display remains blank.

     

    You mention setting the main display to 1 and the external to 2. I can't see any specific options for setting these designations. How did you do it?

     

    Paul

  • by Don Mclellan,

    Don Mclellan Don Mclellan Nov 26, 2014 6:40 AM in response to Gatepark
    Level 1 (15 points)
    Nov 26, 2014 6:40 AM in response to Gatepark

    An example of the current OS X 10.10 (display settings < displays < system preferences) on launch you see two tabs Display & Color.  Holding the Option key will display 'Detect Displays' or if lets say you choose AirPlay display and select an TV then another tab appears, 'Arrangement'.

     

    Use 'Arrangement' to select the main display by sliding the white menu bar to the chosen display, at this moment the current main display will be framed in red (as will the pref pane) and the new choice will take immediate effect on release.  At the same time you can move the second display above, below, left or right of the main to suit actual location of display in relation to the iMac.  

     

    A few years ago instead of the red frame it seems to me it was a large number 1 or 2 displayed.

     

    System report will give you a few details of current displays such as:


    iMac: Display Type: LCD  Resolution: 1920 x 1080  Pixel Depth: 32-Bit Color (ARGB8888)  Main Display: Yes  Mirror: Off  Online: Yes  Built-In: Yes


    Kitchen Apple TV:  Resolution: 1920 x 1080 @ 60Hz (1080p)  Pixel Depth: 32-Bit Color (ARGB8888)  Connection Type: AirPlay



    That being said I have a feeling this may not be the solution you seek but might lead you in another direction. 

    Often resetting the PRAM solves a myriad of issues, perhaps this will help ( opt P R) on start up

     

    Displays:

    iMac:

  • by Gatepark,

    Gatepark Gatepark Nov 26, 2014 9:37 AM in response to Don Mclellan
    Level 1 (0 points)
    Nov 26, 2014 9:37 AM in response to Don Mclellan

    Hi Don

     

    Thanks again for your responses.

     

    I think I'm on the trail of the fault. It looks like I had more than one problem and isolating the specific problem(s) is always difficult in these circumstances.

     

    Firstly I appear to have had a main logic board problem. I replaced the board (£15 on ebay) ad hey presto the original lcd now works, albeit with the same problem that sent me down this path, i.e. multiple vertical lines on the screen. But it was a relief to get the machine back to a working configuration.

     

    Secondly, I think the spare lcd (not the external monitor) I was using also has a problem. If I connect that it still doesn't work. So instead of having my original "Weird Screen Problem) I'm now left with something that I think I can fix, i.e. replacing the original lcd with a known 'good' screen.

     

    If your interested beyond this point you might like to know that the 'spare' lcd that I've been using is actually from a cheaper non-mac laptop. And I suspect you (and anyone else that's been following this thread) will conclude "that's why it doesn't work!". However, I've been using an adapter from Realmacmods which is designed to allow users to replace their broken iMac screens with cheaper laptop screens. So I still need to determine whether the problem with this lcd is the adapter (which costs $49.99) or the lcd itself (£20 on ebay). Hours of fun ahead!

     

    Thanks for all your input and suggestions. Having somebody to bounce things off really helps.

     

    Regards

    Paul