New G5 and CRT having weird issues...

Discussion in 'Macintosh Computers' started by point665, Mar 7, 2005.

  1. macrumors regular

    Jun 27, 2004
    I noticed a weird issue with my new Power Mac G5 (Single 1.8)... I have a 19" Flat Envision CRT hooked up to it, now if the PM is off and I turned on the CRT the PM boots up (just like the Apple Displays did)... Also if I powerdown or sleep my PM it will wake up/reboot unless I powerdown CRT before doing this. The CRT is connected through the DVI to VGA adapter and a Radeon 9600 XT card. I spoke with a friend and he said it shouldnt happen with VGA. Is this normal (and if so is there a way to disable it?) or does it sound unusual to you guys too?

    Thanks in advance.
  2. thread starter macrumors regular

    Jun 27, 2004
    No one?

    Im sure theres a load of people here with G5s and a CRT hooked up using the DVI to VGA adapter...
  3. macrumors 6502a


    Aug 26, 2004
    Try this

    Open preferences click on display

    Check the monitor installed under color option

    Try Generic Monitor or one of the early Apple's

    Then click on option select turns the display on and off.

  4. thread starter macrumors regular

    Jun 27, 2004
    I tried it but where is Options? I dont see it anywhere.
  5. macrumors 68030


    Dec 7, 2002
    Florida, USA
    I dont know if that will work... its not an ADC display, so I don't know why that setting would exist. Plus I can't find that for my CRT on my Powerbook...
  6. macrumors 68020

    Dec 9, 2004
    Yeah, mine did that with a 19" Viewsonic monitor once or twice early on (several months ago), but never since then. Dunno why....

    Hmm, mine never did that. Not very helpful, I know. :)

  7. thread starter macrumors regular

    Jun 27, 2004
  8. macrumors 6502a


    Aug 26, 2004
    If you can't see the options tab then your Mac isn't seeing the crt screen as a digital (which it isn't). So obviously the DVI adapter is wired in a strange way. I wonder if an adapter from a PC digital monitor would correct this or be the same.

    It as got to be that the DVI to VGA adapter wiring and the wiring in your monitor plug not being 100% compatible with each other.
  9. thread starter macrumors regular

    Jun 27, 2004
    So should I try and get another DVI to VGA adapter or get a ADC to VGA adapter?

  10. thread starter macrumors regular

    Jun 27, 2004
    Update: I called Apple Care and spoke with a guy over there, probally first time ever that a "Tech Support" guy knew about a given topic. He was very helpful and said that the problem is actually with the pin out on the CRT displays, that they added a feature which you could power on the computer with just one key. He offered to swap my DVI to VGA adapter but I asked if he thought it would fix it and he said hew knew it wouldnt, so I didnt get it. Im going to try and see what I can find out about the display Im using, maybe somehow fix it on that end of the cable.
  11. macrumors 6502a


    Aug 26, 2004
    Here are the pinouts for the CRT and the DVI plug. When I have rewired these connectors in the past I have never had to connect the ID bit on pins 4 / 11 / 12 / 15.

    15pin H/D Connector (

    Pins numbers and signal type
    1 red
    2 green
    3 blue
    4 ID bit 2
    5 n/c
    6 red ground
    7 green ground
    8 blue ground
    9 n/c
    10 ground
    11 ID bit 0
    12 ID bit 1
    13 H sync
    14 V sync
    15 ID bit 3 or SCL

    DVI Pin Signal (

    Pin numbers and signal type
    1 T.M.D.S DATA 2-
    2 T.M.D.S DATA 2+
    3 T.M.D.S DATA 2/4 SHIELD
    4 T.M.D.S DATA 4-
    5 T.M.D.S DATA 4+
    7 DDC DATA
    9 T.M.D.S DATA 1-
    10 T.M.D.S DATA 1+
    11 T.M.D.S DATA 1/3 SHIELD
    12 T.M.D.S DATA 3-
    13 T.M.D.S DATA 3+
    14 +5V POWER
    15 GND
    17 T.M.D.S DATA 0-
    18 T.M.D.S DATA 0+
    19 T.M.D.S DATA 0/5 SHIELD
    20 T.M.D.S DATA 5-
    21 T.M.D.S DATA 5+
    23 T.M.D.S CLOCK+
    24 T.M.D.S CLOCK-

    TMDS (transition minimized differential signaling)

    As you can see from both connectors pinout's the wiring is pretty straight forward to make an adaptor cable.

    The interesting thing is that the Apple supplies an adaptor thats has a DVI Single link connector on it, which means it should be wired for both analog and digital pins.

    The adaptor that Apple should surely haave supplied is a DVI -A which is a High-Res Analog adaptor and only has total of 17 pins in total.

    This is why I wondered if they have done something strange inside their adaptor cable hence all your problems.
  12. thread starter macrumors regular

    Jun 27, 2004
    It probally is a problem wth their adapter, well that is causing my and other's problems... Which pin would control the signal to power on the machine when turning on the display?

    Thanks alot :)

    Edit: I've been looking around alot, do you think that a DVI-A to VGA adapter would solve the problem. I am thinking that because the DVI-A is analog only it would not send the digital signal (Because it lacks the digital pins) and thus would not wake-up/power-on the machine.
  13. macrumors 6502a


    Aug 26, 2004
    Information on the DVI specification can be found here

    Here is my thoery what it might be, now someone correct me if I am wrong here.

    Take a look page 23 and look at Appendix C

    If you look at this page, I think the +5v is the key here. This is connected with the power management in the DVI specification.

    If your CRT is using the 5v+ on pin 9 of in 15 HD type connector then this may be the cause of the weirdness as it looks like this acts like a way for the DVI powermanagment to detect the state of the monitor whether its in standby - switched on or switched off.

    You could test this by making a patch lead with 15 pin male one end and a 15 pin female socket at the other and not connect pin 9. This would also save you chopping the end off your monitor cable trying to rewire it.
  14. thread starter macrumors regular

    Jun 27, 2004
    Im going to go look for my VGA exension cable tommorow... Or maybe goto radioshack and see if they have anything I can use, so I can test it. Is there a possibility of this damaging anything?


    Edit: What about this... Hot Plug Detect (HPD) - Signal is driven by monitor to enable system to identify the presence of a monitor. Its on page 23 under 2.6 .
  15. macrumors 6502a


    Aug 26, 2004
    I would just make sure that you get good clean connections on the pins - those plugs are a swine to solder, make sure the solder is fluxed else the wires won't hold.

    The connections I would use are

    pin 1 Red
    pin 2 Green
    pin 3 Blue
    pin 6 Red Ground
    pin 7 Green Ground
    pin 8 Blue Ground
    pin 10 Sync Ground
    pin 13 H-Sync
    pin 14 V-Sync

    This should be enough to get the picture on the screen. On both the male and female ends you will notice that pins are marked differentlly. Looking from the back of both - pin one is on the left handside whilst on one whilst on the other, pin 1 is on the right.

    If you are going to build the cable yourself then I would write the colour in the cable and which pins that you assign them to, this will make life easier.

    If the hood is made of metal then most cables the outer screen is used as your earth this can be soldered onto the inside of the metal hood.
    Or it is soldered to the outer metal rim of the plug above the pins ( this wire is then inside the hood )

    You may be able to purchase a ready made lead that has is already wired up that has a plastic hood that is bolted together, then all you have to do is to remove the hood and check for the +5v pin 9 and desolder the wire.

    I would then insulate any desoldered wires from each other, as to avoid any short.

    If you get the H-Sync and V-sync wires crossed at one end then you won't get a picture.


    If your cable does not work then disconnect it from your monitor and MAC before making any alterations - heat from your soldering iron can damage your equipment.

    Make the changes needed then test the cable again.

    I take no responsibility here for your ability to use a soldering iron and for making up cables - their are companies out there that will make cables up for you. Or like I wrote a bit back, get a ready made cable that can be modified. But test the cable first to see if it needs modifying.

    I hope that this solves the problem.
  16. macrumors 6502a


    Aug 26, 2004
    I just remembered you can check whether your monitor is using the +5v by simply looking at the pins on the plug - some manufacturers tend to cut out the pin 9.

    When looking at the plug you get two pins missing on most CRT screens plugs they are pins 5 and pins 9

    If pin 9 is missing then the problem is either directly in the plug on the CRT or like I said with their adaptor.

    If I was in the same situation I would first build the patch lead and if that fails to solve the problem then I would cut the plug off the end of the monitor cable and rewire it onto a new plug and test it that way. I don't know if its possible to obtain a DVI Plug and hood, as you could attempt to wire the monitor directly into the new DVI plug, bypassing the Apple adaptor.
  17. thread starter macrumors regular

    Jun 27, 2004
    Thanks alot,
    I will test it with a VGA extension cable (probally go down to radioshack and see if they have a VGA box-type connector first, and modify that). I will post the results when I get them.
  18. thread starter macrumors regular

    Jun 27, 2004
    I found this while looking around on Apple Support Discussions...


    The computer restarts after it is shut down. This occurs when certain third-party VGA and DVI displays are connected to the computer's digital video interface (DVI) port.

    Products affected

    Power Mac G4 (Mirrored Drive Doors)
    Power Mac G4 (FW 800)
    Power Mac G5
    Some third-party DVI displays
    Some third-party VGA displays (with DVI to VGA adapter)
    Apple graphics cards with both an ADC and DVI connector

    This does not affect displays that use the Apple Display Connector (ADC).


    Although rare, some third-party displays deviate significantly from the industry design standards for the implementation of the DDC (Display Data Channel) clock signal.

    If your computer restarts after shutdown or wakes after being put to sleep with certain displays connected to the DVI port, these symptoms can be prevented by connecting the display to the video card's ADC port instead of the DVI port.

    It may be necessary to purchase an ADC to VGA or ADC to DVI adapter cable. Companies offering ADC to VGA or ADC to DVI adapters include:
  19. macrumors 6502a


    Aug 26, 2004
    Have you tried it yet - and does this cure your problem

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