Sunday, January 30, 2011

Apple Cinema Display / iMac Mod Wiring the Neck Update

As I mentioned previously there are really two ways of getting the cinema display signal through the neck.  The first method was to remove the pins from the connectors when possible, remove all existing wires from the 20" neck and replace them with the cinema display cables.  This method has the advantage of minimal soldering (especially of the very small cables), but getting the wires through is tedious.  Although the wires are similar the shielding is thicker on the cinema display cables.

The second method is to use the existing wires in the iMac neck and solder them to the Cinema Display Connectors at each end.  (With one notable exception).  To start I removed all the protective tubbing from the cinema display cable.  The cable is composed of 4 separate wires.

1) The Power Cable - 3 wires - including 24V
2) The DVI cable  -  This cable actually splits into two parts on the monitor side of the cable
     A) TMDS Signal Wires - The equivalent of the black cable of the iMac - 4 triplet wires = 12 total
     B) TMDS Power/Data/Clock - The equivalent of the gray cable.  This contains the clock, data, hot plug, EDID, and ground.  There are less cables than the grey cable because the power (VCC and ground cables) come off from the lcd controller.
3) Firewire - I discarded
4) USB - 4 cables

The iMac has 4 cables as well
1)Microphone/LED
2)Inverter Cable
3)TMDS - Black
4)TMDS - Gray


 As I showed in my previous post, I didn't believe any existing wire was similar in gauge to the power cable, so I did have to open the neck.  I removed the microphone/LED and replaced it with the similarly sized Cinema Display Power Cord.  I then spliced the DVI cable to the existing iMacs Black and Gray cables.  As there are 4 extra wires in the iMacs grey cable I used those for the USB.  So the inverter cable is unused.  So if you need the room it can be discarded, but I am hoping to use those cables for the touch screen.  Remember to put the DVI end in before soldering the connector can not fit through the hole in the top of the base.


 In essence I simply cut the Apple Cinema Display in half and spliced the iMac Cables in the neck between them.  With the exception of the USB cable, I used the iMac cables that were meant to carry that very signal.  Meaning I spliced the Clock to the clock, EDID to EDID etc.  The most important thing is to write down which wire you spliced to so you can correctly match the wires back up on the other end.  Knowing the function of the wires is useful, however, for troubleshooting purposes.  The guide I used is shown below.

   Having done both methods, I would recommend using the splicing method.  The reason for this is that although there is more soldering, you end up with a surplus of wires.  Thus, if you want to add firewire capability, a touch screen etc.  you have that option.  Also, it is easy to damage the neck when trying to force the extra wires through.  Testing it out:

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7 comments:

  1. Looking good J,

    Getting ready here.
    I just located a busted 20" G4 for coffee money & a 20" display on ebay.
    I will attempt the screen mod as you have done & if it works out then I'll probably just sit the dome over a fairly intact MM.

    I thought this would never happen but your cinema display idea has fired me up!

    Cheers,

    Roger (can I PM or email you on this site?)

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  2. I'm glad - it actually works really well, I am almost done with my mod. Please feel free to email me at dremeljunkie@gmail.com. Good luck

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  3. Sometimes we do not get the desired seat/place in the cinema hall. Cinema 21 Popcorn

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  4. Look where the electrical wires attach to the breaker screws. Also look at the electrical ground wires because they will be the same material as the hot wires. Solder coated wire also looks silver so be careful not to confuse the two. One is a potential fire hazard and one is not.www.jimrohal.com

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