Saturday, November 13, 2010

Revisiting the G4

Part I:

So much for changing gears. I have taken a long break from the iMac G4 mods but recent developments have gotten me excited to revisit the designs. First, the excellent work done by the folks over at macrumors especially pgee70 who has solved several of the problems caused by splicing dvi directly to the 15" monitors tmds cable.  As well the original japanese modder who performed the first successful splice.  I encourage anyone interested in this mod to check out their work.  One of the most annoying components of this mod is opening the neck and the ability to avoid doing so would be a gigantic step forward.

Secondly - cheaper and lighter touchscreens.  Although most do not seem to share my enthusiasm for the iMac G4 as a touchscreen computer, I can say firmly that it is far and away the best design for a touchscreen computer I have come across so far.  I know companies patent everything all the time but here is apple's patent filing for a touchscreen imac courtesy of engadget.  Look Familiar? My touch screen 17" mod makes a fantastic kitchen / family room computer.  It functions as a small internet TV, video jukebox, and web browser.  Now we are seeing capacitive screens available at a reasonable cost.  However, the iMac does have a fatal flaw with touchscreens - they MUST be light.  Because all the weight is placed at the front of the iMac this often causes problems with "arm drift".  Especially with the weight sensitive 15".  However, new film-to film touch screens eliminate this problem as they are essentially weightless.  So, I will try the15" DVI splice mod, but I will also incorporate a film-to-film touchscreen.  My goal will be to not open the neck if possible and use only the extra wires (microphone/LED/dimmer) to connect the resistive screen to the base.  Although I have read that people have done the same with the 17" there is no pinout or instructions available online.  I know many people are interested in converting their 17" using this splice technique and I have plenty of extra arms and iMac components to compare and experiment with - so coming up and verifying a pinout of the 17' should be possible.

I will be posting a parts list for the 15" mod shortly, and will post updates as I move along.  I will try to work on the 17" pinout and guide as well, though will unlikely take this to a completed mod.

ADDENDUM: As you can see from my recent posts I have decided to bypass the 15" and focus on the 17 and 20" iMacs.  The 15" mod has been done several times and I believe replicating it won't really add much to the community.  Still, if you are doing this mod and need any help beyond what is available from macrumors and other sites listed, I'd be happy to answer any questions.

Part II:

Other newer developments include smaller form factors.  I have yet to complete an all-in-one - my 17" hides behind it a computer.  It is possible to shoehorn a mini itx board at the right angle into the base or a caseless last generation mac mini.  Despite this - I would be very hesitant to put anything hotter than an atom-ion combo in the base.  The G4 was designed as a convection cooled computer.  The airholes are located next to the exhaust fan and the mobo is otherwise surrounded by a heavy metallic faraday cage.  So there is NO air movement at the bottom of the dome.  However, some decent smaller form factor boards specifically the embedded compact have just come on the market.  Although they use mobile processors - a core 2 duo is would still make for solid computer.  Also, using the splice technique no monitor components will waste precious space in the dome.
The 20" still remains the toughest challenge.  While it takes only a power source and a few resistors to turn on the backlights to the 15" and 17" mods - I have never been able to get the inverter to work unless connected to the original iMac.  Because no aftermarket inverter is thin enough to fit inside the monitor casing - it has to go in the dome.  As a result, there are 6 high voltage wires that need to traverse a moving metallic neck.  It was because of this that I disassembled my original 20" mod.  I did not believe I had adequate shielding on the wires.  However, I have recently come up with a possible solution that I will be investigating in the next few weeks.  Thanks for following along and as always feel free to ask any questions.


  1. I look forward to the 17" pinout. Started this mod not so long ago, very disappointed its not the same pinout at the 17" (Should have done my research!) :)

  2. Hi, searched all over. Im very excited about the imac g4 17" pinout so I can splice to dvd, like currently being done with the 15" model.
    I've searched all over with no joy.

  3. Andrew, how is your 17" mod coming - were you able to follow the pinout?