Weird DVI problem I've never seen before

Discussion in 'PowerPC Macs' started by Project Alice, May 23, 2019.

  1. Project Alice macrumors 6502a

    Project Alice

    Joined:
    Jul 13, 2008
    Location:
    Post Falls, ID
    #1
    So, I just had the weirdest problem with a couple PowerBook G4s that I have NEVER even heard of before.
    Let me give you a bit of back story here before I go off on this tangent..

    My main setup is my Mac Pro 5,1 using a 23" ADC Acrylic Cinema Display plugged into this KVM switch, along with a sawtooth G4 and two PCs. Well, as some of you may know Windows 10 loves to turn the brightness all the way down on this display with no way of turning it up again without using this. I had just finished a (failed) upgrade to Win 10 1903 on my 5,1 that kept BSOD'ing seconds after reaching the desktop (theres a thread on this in the Other OS section on here). Because of this, I was not able to brighten the display again because it had kept blue screening before I could open the brightness app.
    This is where the PowerBooks come in. The only way I've figured out how to change the brightness of an ADC display when this happens is to plug it into a PowerBook (for some reason the sawtooth doesn't give a brightness slider nor does the Mac Pro under Mac OS). Well, I plugged the DVI cable from the one of the machines using the KVM into a TiBook running leopard. It connects, then a few seconds later the PowerBook just shuts off like I removed its battery. WTF? I turn it back on. It does it again before it can even finish booting. I'm already annoyed enough at Windows failing and making my display nearly unreadable, so I grabbed another PowerBook, this time a 15" AlBook. It does the same thing. Both of these PowerBooks have working batteries, but were also plugged into power at the time.
    I eventually plugged the display directly into that PowerBook, and it worked as normally. I fixed my display brightness and put it back into the KVM.

    What I can't figure out is why this would cause these PowerBooks to just shut off. There isn't anything special about the DVI cables used on the KVM and it uses just a standard single-link connection just like the 23" display does. The KVM works fine on every other devices I've plugged into it.
     
  2. Slix macrumors 65816

    Slix

    Joined:
    Mar 24, 2010
    #2
    Hang on. I'm confused. You have an ADC Apple Display but you are plugging it into the KVM without an adapter? Are you using an ADC to DVI adapter then plugging that into the KVM?

    My 17" Acrylic Apple Studio Display doesn't have a brightness slider on my G4 MDD either. So maybe the KVM doesn't provide enough power from it to the display to get it to fully brighten on Windows (and causes the PowerBooks to shut off)? If the display works fine without the KVM I'd imagine the issue is the KVM.
     
  3. Project Alice thread starter macrumors 6502a

    Project Alice

    Joined:
    Jul 13, 2008
    Location:
    Post Falls, ID
    #3
    No I am using the ADC to DVI adapter.. I figured that was a given as there is no other way to use that display on any non ADC computer.

    The monitor works fine on Windows, just Windows dims it after a few seconds of logging in. I'm sure its some Windows bug. i use the app I linked to above and I can turn it back up, not a big deal.

    The only reason I brought up the Windows problem was to explain why I was plugging a PowerBook into a KVM in the first place.. Just to fix my brightness while I was dealing with Windows issues.
     
  4. Amethyst1 macrumors 6502

    Amethyst1

    Joined:
    Oct 28, 2015
    Location:
    Germany
    #4
    Which version of OS X are you running on the Mac Pro? If it's Mavericks or later, the absence of the brightness slider is due to the removal of
    • AppleBacklight.kext
    • AppleBacklightExpert.kext
    • AppleUSBDisplays.kext
    I got the brightness slider in Mavericks by putting those kexts back in (from 10.8.5) but have never tried this with later versions.

    Source
     
  5. Project Alice thread starter macrumors 6502a

    Project Alice

    Joined:
    Jul 13, 2008
    Location:
    Post Falls, ID
    #5
    Its Mojave. What would be nice is if I could get the slider on my Sawtooth G4.. It should support it I thought, but for some reason it only shows up on PowerBooks.

    Edit: The sawtooth is running Leopard (also Tiger but it pretty much stays in Leopard).
     

Share This Page

4 May 23, 2019