Mini DisplayPort to DVI Adapter with DVI to VGA adapter..?

Discussion in 'MacBook Pro' started by nitewolfgtr, Oct 15, 2008.

  1. nitewolfgtr macrumors regular


    Jul 20, 2008
    Buying both the Mini DisplayPort to DVI adapter AND Mini DisplayPort to VGA adapter is pretty expensive...

    I was wondering if I purchase the Mini DisplayPort to DVI adapter, will I be able to use a simple DVI to VGA adapter to use it as a VGA adapter also???

    I'm not sure if the Mini DisplayPort to DVI adapter only sends digital signal or digital & analog signal.

    Any help would be appreciated!

  2. donbenjy macrumors 6502

    Oct 15, 2008
    I have the same BUMP!

    The Apple store didn't know when I asked.
  3. shoulin333 macrumors 6502a

    Jun 26, 2007
    I am not home, but i can try and report back in about an hour.
  4. squeeks macrumors 68040


    Jun 19, 2007
    umm, yeah? why not?

    it has to turn it into a regular DVI signal to run a DVI monitor reason a DVI to VGA adapter would not work too
  5. djellison macrumors 68020

    Feb 2, 2007
    Pasadena CA
    I bet £5 for charity that it doesn't work (I don't know yet).

    I bet that not only does it not work, but that Apple intentionally designed it and went out of their way to make sure it doesn't work - to force people to buy multiple adaptors.

    Like the effort they went to, to make the USB extension lead for their keyboard incompatable with any other USB device.

  6. squeeks macrumors 68040


    Jun 19, 2007
    #6 works on the DVI port on the non-unibody MBP, i can take any non mac DVI to VGA adapter and it works fine, as does any DVI to HDMI adapters, so im guessing itll still work
  7. donbenjy macrumors 6502

    Oct 15, 2008
    you mean design wise? They can't really make the DVI end proprietary like with the usb extension, because it needs to be able to plug into any DVI port, including the one on my DVI > VGA adaptor! The only way it wouldn't work is if (and bear in mind I know nothing about DVI here) in the current/old large DVI ports, a few pins carry an analogue signal for the VGA, and so all the adaptor does is "sees through" the DVI connector, and ignores the digital pins...they could very well be able to remove say, one key pin from the DVI end, which will work fine on a DVI display, but not with the VGa or S Video adaptors etc. Saying that, we know that the DisplayPort will be able to output an analogue signal to VGA, but not how the adaptors. The question is not "can I?" because it's certainly possible to create an adaptor that will handle dvi adaptors, or presents the full range of options in the DisplayPort, but in the form of a DVI connector...But as Doug said, Apple could easily have stopped it from working that way! :(

    Shoulin: how did you get on?
  8. MusicallySilent macrumors member

    May 23, 2007
    Don, it may plug into your dvi port

    However, there are multiple types of dvi

    For your VGA adapter, all it is doing is taking the analog pins from the dvi adapter and re-arranging them into vga locations. However, if apple didn't connect the dvi's analog pins to the notebook in that adapter, it wont work.
  9. thedude007 macrumors newbie

    Oct 16, 2008
    Stupid displayport

    I was thinking the same thing myself. I just bought a new macbook and am waiting (impatiently) for it to arrive. I was a little put off by the price tag on the new proprietary minidisplay port that will set me back $30 to connect to my LCD display and another $30 so that I can use my new computer for presentations as the projectors I use only run on VGA. I found a DVI to VGA connetor lying around that my boss bought a year ago for his MBP. Noticing that the pins were slightly different, I enlisted the help of my good friend google and came across an image of the different DVI connectors ( The old miniDVI to DVI connector was the DVI-D while the DVI to VGA adapter has a male DVI-I connection (both single link). If you use this adapter on the old MBP, it can be used on any DVI type (except A). If apple stays consistent with their previous design, the mini displayport DVI will be a male DVI-D so we will be stuck forking out the extra money for a second connector.
  10. donbenjy macrumors 6502

    Oct 15, 2008
    hmm...looking at wikipedia, it seems that the analogue pins are the 4 around the + shape, so if they aren't there, then we're stuffed! Looks like Apple havecleverly covered that bit up so far...I think we need someone with an adaptor (and I'm not spending £20 on a test, as if it doesn't work, I need VGA like 10 times more than DVI, but my friends all have DVI adaptors. Seeing as they're charging $100 for the dual DVI connector, then it's probably likely that they'll rip us off with this too, yes?
  11. vlestat macrumors newbie

    May 14, 2008
    If thedude is correct, which I am sure he is, all we really need (hopefully) is a picture of the DVI-side connector on the mac part to see if there are physical connections in the right place. Has anyone got one of these adapters yet that could upload a picture? I'd really like to know, because I have ordered a new macbook from my university computer store alongside one of these adapters (DVI) and would like to keep that, but if I can't use my cheap DVI to VGA adapter I will have to order the VGA one :(
  12. tnhick macrumors member

    May 8, 2008
    I can confirm that Apple has officially screwed us over, again, as there are no holes around the MINUS sign on the Right side of the DVI port, there is no plus, it is simply the minus, straight line, without any holes around it arrrgh!
  13. Chronocento macrumors newbie


    Jan 15, 2008
    Messina, Italy
    I have the DVI-VGA adaptor of my Mac Mini in my hand now.
    From what I can see, it is a DVI-I (single link) adaptor. Instead the one of the mini DVI-DVI adaptor is a DVI-D (dual link).
    The only problem if you try to connect this two adaptors comes from the 4 pins around the "-" pin in the DVI-VGA adaptor. But from what I can see, this 4 pin are a bit shorter than the others, so maybe it can work, even if you can't connect the adaptors "all the way down".
  14. shoulin333 macrumors 6502a

    Jun 26, 2007
    Doesnt work...

    apple's DVI - VGA adapters are Dual link

    Apples's Mini display port - DVI is single link

    ... might work if you break off those 4 pins (eek) or pick up the more expensive Mini display port - Dual link DVI adapter
  15. thedarkhorse macrumors 6502a

    Sep 13, 2007
    but you don't need to use apple's you could use any dvi-vga adapter, they're cheap and free if you ever bought a video card.
  16. GeeYouEye macrumors 68000


    Dec 9, 2001
    State of Denial
    Three of those four pins are the RGB VGA pins. So you can't break them off and have it still work.
  17. hvfsl macrumors 68000


    Jul 9, 2001
    London, UK
    Assuming the mini display port really is an industry standard (and not just an Apple version of Displayport), then hopefully some Chinese company will come out with a cheap adapter (since they can't cost more than $1 to make).
  18. e-dard macrumors newbie

    Jun 15, 2009
    Hey all,

    sorry to dig this up again. I have got a new 13" MBP. Rather than paying silly money to buy an official miniDisplayPort to DVI (which of course is only DVI-D anyway) I bought a third-party one from eBay.

    The third-party one, although bulky and ugly, does the job perfectly on a DVI monitor. I should point out that importantly the TP cable is DVI-I, meaning it should carry an analogue signal in the absence of a digital one.


    However, when I put a VGA-->DVI adapter on the end of the cable, and then attach a VGA monitor I get nothing.

    More precisely, the laptop correctly recognises the external monitor, shows me all the correct modes of the external monitor, and allows me to manipulate the monitors settings. However, no picture actually appears on the external; indeed, the monitor states there is no VGA signal present.

    Now then, the question is: Is this likely a lazy third-party who didn't bother to connect the Analogue pins in the DVI connector to the displayPort part of the cable, or is there something that Apple has done to make this infeasible. I should point out that I have tried to get this working on multiple VGA monitors (each one is recognised, but no image displays).

  19. getz76 macrumors 6502a


    Jun 15, 2009
    Hell, AL
    Are you sure this is not a HDCP issue? I thought DisplayPort would only output digital content, so there would be no way to get an analog signal out of it. I am not sure, but I do recall DisplayPort (and mini-DisplayPort) being HDCP...
  20. crzdmniac macrumors regular

    Aug 23, 2007
    Monoprice has a mini displayport to DVI, HDMI, and VGA. They do state that you CANNOT convert the DVI to VGA with a converter. I'm guessing they have specific circuitry to do the conversion in the big ugly box. I believe the converter to VGA is ~$20 USD.
  21. apeacock macrumors member

    Dec 9, 2008
    The DVI ports that support both VGA and DVI can do so because they are sending both DVI and VGA out on different pins. My best guess on how this works on the mini-displayport or mini-dvi is that the mini displayport/dvi doesn't have room for enough pins to send both the DVI and VGA signals at the same time, which would allow compatibility with a DVI -> VGA adapter. What is probably happening is the computer is detecting if a DVI or a VGA connector is plugged in, and then sending the correct analog/digital signals. Since a DVI adapter is plugged in when you try to use a DVI->VGA adapter, only a digital signal is being sent and there is nothing for the VGA input to use.

    This isn't an official reasoning or anything, it's just my best guess based on what I've seen.
  22. Joruus macrumors member

    Jun 14, 2009
    The Nvidia GFX in the UMB(p) is digital only, no vga out, ever.

    End of Story.
  23. apeacock macrumors member

    Dec 9, 2008
    I haven't tried it personally, but the UMBP specs from Apple disagree with you:

  24. lozanoj83 macrumors 6502a


    Mar 5, 2006
    Southern California
    Wrong about that, I own a mini-display to VGA on my uMBp, and it works...
  25. e-dard macrumors newbie

    Jun 15, 2009
    Hmmm, OK, thanks for that info. I am in the UK so will check out eBay for another one.

    This seems like a sensible hypothesis.

    This is just a silly conjecture. Why would apple stop you connecting their laptop to 90% of all projectors out there!!! Think of all the people that rely on projectors for presentations!

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