How to turn iMac G5 (no iSight) built-in display OFF?

Discussion in 'PowerPC Macs' started by NeverhadaPC, Jan 27, 2010.

  1. macrumors 6502



    I have an out-of-warranty 2005 iMac G5 running OS X 10.5 in my bedroom. The screen is very unreliable to the point where it stayed off all the time or gave weird colors and I had to purchase an external monitor (via mini-VGA).

    I have installed (successfully) spanning tools to allow both extended desktop (2 dual monitors) and mirrored display (2 monitors showing same thing) --- however, after hooking up the external display, the iMac's bright display lights up my bedroom.

    Problem: I want to turn OFF my built-in display (i.e. no backlight) and have my external monitor act as my main display --- avoids having two displays eating electricity.

    Is this possible? (using any Terminal commands?)

    I don't want the computer to sleep, just to turn off the main display (even manually removing wires will work, if I can find a how-to guide on this!)

    Thanks a bunch!
  2. macrumors 65816


    Brightness controls.
  3. macrumors 6502


    Brightness control is very limited on the iMac G5 --- It's not like the MBP where you can turn off the screen.
  4. macrumors 6502a

    there is a 20 or is it 24V power output from the psu on the 2005 ALS version. iirc this is for the screen.

    Can confirm if you cut these wires you can still remotely access the iMac from another mac - or at least i could a few months ago.

    Whether you're external monitor will still work with those wires cut - can't say for sure. I'd guess at a yes.

    Think the wires in question are the 2 leftmost wires as you look down at the psu connector when it's plugged into the logic board. I mean the 2 wires that are one on top of the other not side by side.

    You'd obviously want confirmation of all of the above from someone else - but from the perspective of reverting back - there must be loads of ways of cutting and rejoining the wires or maybe removing the pins from the connector in a way that you could put them back.

    also worth bearing in mind that if you mess around with psu's and you don't know what youre doing there's various risks - permanent damage to your iMac or even worse you!
  5. macrumors 6502


    I will look into PSUs for iMac G5 and see if wires are removable or well-documented somewhere...
  6. macrumors 6502a

  7. macrumors 6502


    Thanks. While my capacitors are fine on the iMac I have not checked the PSU's caps.
  8. macrumors 6502


    I am still surprised there is no way to turn off the main display on G5 iMac when external monitor is in place via software/preferences/terminal...

    Right now I just have a large black opaque terminal window covering the main display in my extended (spanning) desktop mode.
  9. macrumors 6502a

    capacitors/overheating was the reason i had those bookmarked.

    but i thought that there might be some sort of psu info you could use to id the wires you were looking to cut?
  10. macrumors 68040


    The exact same thing happened to my iMac, did you find a solution to turning the display off?
  11. macrumors 6502


    Nope. The screen goes on and off as it pleases but my external monitor is just fine and does the job very well. I did download a firmware app that allows me to output at a higher resolution and in wide screen. A google search should lead you to it. It helped the most.

    If you find a non-super-technical way of turning off main display please post it here as well. Good luck
  12. macrumors 65816


    As others have mentioned, the best thing to do would be to remove power to the inverter for the LCD panel. Some iMac G5's have plugs that can be easily removed from the inverter, but i'm not sure if yours looks like that. You might want to check for a disassembly guide for your model to see how difficult it might be.

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