Wednesday, October 26, 2011

The 15" iMac G4 Pinout (Courtesy of pgee70)

Here is the pinout from the 15" iMac G4 Mod that inspired all of my subsequent TMDS to DVI mods

This is the original pinout created by pgee70

- I highly recommend checking out some of his comments and posts on the macrumors forum:

- As well as some of his incredible mods on his youtube channel:

Thanks, Pete


  1. Is that for the 15inch 700 MHz??

  2. how do you hook up the inverter I don't really understand

  3. As far as I know its for all 15". I myself have never done the 15" version and you may find the macrumors forum helpful. But, at the bottom of the chart you see #1 - 6 labelled Mac Inverter cable. A cable in the dome of the iMac should correspond to the color of this 6 wires. Leave the first two *brown and purple" unconnected. Connect green to 5V DC with a 1Kohm resistor in-between. Connect red directly to 5V DC, Black to Ground, and Blue to 12V DC. That should be all.

  4. Hi JBerg dunno if you still see all this stuff but anyway:

    You've inspired me to make the old kitchen PC and I've managed to get a 15incher.
    I understand the Inverter part of the pinout but not the main part. There are two things which confuse me:
    Firstly what the pin numbers on his diagram are. There appears to be 18 pins and 24 labels? I think he's just not drawn on pins 4,5,12,13,20 and 21 right?
    Secondly in your guide for 17 inch you speak of the colours as 'red to red' or 'blue to green'. All the wires on the 15inch are solid. Does what you say only pply to 17 inch model?

    Cheers for all you've already done, Even better if you reply!

    1. Ok, hopefully this will clear things up. I'll start with what I know best, the "brown to red" applies only to the 17 and 20". TMDS can be broken down into 2 parts, control (power, clock, on/off etc) & signaling (the color channels that tell the pixels what to display and how fast to refresh). The signal channels are 0,1,2,& C(stands for signal clock). Think of it as red, green, blue, refresh rate (oversimplified). Each one of these channels uses 3 wires to get its info to the LCD, a positive, negative, and shield wire. In the 17 and 20" models, these triplets were put into a larger wire which gave off three smaller wires containing these signals. In the 15" they are twisted around each other and have their own color. They are not contained in a bigger wire.

      The DVI PIN number is the pin position that corresponds to where that signal would be on a female DVI-D connector. He has an illustration at the top. DVI has 3 rows of 8 pins which is 24. However not all pins are used in all monitors. There are only 18 pins used on most monitors (there are extra TMDS channels that are not used here). The LTM PIN number likely refers to the cable at the top of the neck that plugs into the LCD itself. Counting the pins from left to right. (As there is no reason to open the top, this PIN number is not important).

      What you need to do is to plug the monitor cable wires based on the color he shows you at the far right. Take that pin and hook in into the correct spot on a DVI connector. If his illustration is over simplified simply google DVI Pinout and you will see more detail. The numbering system is standardized and again based on a female connector. Hope this helps

    2. Thanks for the reply, as usual more digging after I asked meant i worked it out but its good to see we both agreed.

      the only issue others who may find this and need some help with a 15" is the female bit of GPU pins are a smaller diameter than the male pins on most DVI's. i found they can be easily expanded by gently pushing a safety pins sharp end down them though.

      Thanks again!

    3. What did you do with the back inverter cable? I Have the same 15" but I have less wires than the 17" on the video?

  5. The same for me. I applied the Pgee70 pinout in my G4 15 ", but still only a gray screen. Computer finds a new display but not image at all. Any ideas? Thanks for any answer!