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:

http://forums.macrumors.com/showthread.php?t=224698&page=9

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

http://www.youtube.com/user/pgee70utube

Thanks, Pete

The Two 17" iMac Necks

*NOTE: The Inverter Charts have been updated.  As I noted earlier, a reader noted flickering of the backlights with 12V connected to the RED line and it stabilized when connected to 5V.  I initially thought there was some inverter variation but after another confirmation from a reader I checked my old notes and had clearly written "Red - 5V".  I made a mistake when putting together the Inverter diagram for the blog.  Thank you to my readers and my apologies for any inconvenience.  Please note the charts have been corrected to reflect that RED is connected directly to 5V for both 17" iMac necks.

So I have fairly intact versions of both of the 17" necks and they are VERY EASY to tell apart - even if you don't know which 17" iMac the neck originally came from.  They are also VERY DIFFERENT - so know which one you are using before proceeding.  These are the only two part numbers for 17" necks I have been able to find.  Other variations or small differences may exist, I can not be certain.  Remember, you always have the option of opening up the monitor and looking at the JAE connector.  Because they all use the same LCD, the pin number/position will always be the same.  I will focus on the differences.
My previous post/17" pinout detailed what I will call:


NECK A: This is part #661-2825 and is the for the 1ghz and 1.25ghz 17" iMac G4.

 Here is a picture of the JAE connector.  Notice that the pins are glued onto a black board which is then encased in a silver connector with prominent push clasps on the sides.

 Here is the inverter - LCD side.  Notice the colors from left to right (Blue, Black, Red, Green, Purple, ORANGE)

 Bottom of the inverter again you can see the presence of an ORANGE wire

 The bottom of the video cable that plugs into the motherboard had this number on it (620-2305).  I don't know if this is universal across all of these necks, but I wanted to point it out).

DVI pinout A - 1 or 1.25ghz iMac neck

Inverter Pinout A: 1 or 1.25ghz Neck

So here again is the DVI and Inverter pinouts for Neck A recognizable by:
1) Part #661-2825
2) Comes from a 1 or 1.25ghz 17" iMac G4
3) Has a black/silver JAE 30 pin connector to LCD
4) Has an Orange Wire in the inverter cable
5)??Has the number 620-2305 on the motherboard side of the video cable

NECK B: This is part #661-2716 and is the for the 800mhz 17" iMac G4.

I have peeled back the aluminum foil, but you can see that the JAE connector that connects to the LCD is one where the pins snap into a beige connector and there are no clasps on the side.

Here is the inverter (LCD side).  Notice the colors from left to right (Blue, Black, Red, Green, Purple, OFF-WHITE) 

 The bottom of the inverter (removed from connector) again shows the OFF-WHITE colored wire [NOT ORANGE].  There is also a number on the motherboard side of the video cable.  Again, I'm not sure how specific this is.  (620-2122).

So here is the new TMDS to DVI and Inverter pinouts for Neck B recognizable by:

1) Part #661-2716
2) Comes from a 800mhz 17" iMac G4
3) Has a beige JAE 30 pin connector to LCD
4) Has an Off-White Wire in the inverter cable
5)??Has the number 620-2122 on the motherboard side of the video cable

DVI pinout B - 800mhz iMac neck

Inverter pinout B: 800mhz neck

*** I have come across a neck that has the LCD cable of a 800mhz iMac, however, its inverter cable has an orange wire.  As I obtained this second hand, this could have been the result of a repair and may not be standard.  As both are left floating, it doesn't matter for the inverter, however, I can now have doubts if this can be used to differentiate the two necks.  Luckily, there are other differences.

Conclusion:
There are so many differences, there is a Brown cable in one, an Orange in the other.  The order of the rest of the wires is completely different.  Even the Clock/Data cables are reversed White/Black.  While I myself have set up Neck A, a reader of my blog has gotten it working with neck B.  Obviously the color of the wires really doesn't matter its what pin they connect to thats important.  As there may be a slight difference in what I call "blue vs. purple" etc.  Here is a close up of the 2 JAE connectors and the order of their wires (pin 1 position is on the left to pin 30 on the right).

NECK A: 1 or 1.25ghz 17" iMac

I'm excited to see some of the projects people come up with - I also like confirmation that things are written clearly and are correct.  So comments are appreciated - thanks.  Good luck and feel free to ask any questions.

Inverter Frustration

After success with the 17" I was hoping good fortune would carry over to the 20" mod.  However, the 20" Inverter has continued to be a problem.  As the DVI/TMDS is essentially the same as the 17" (with just extra power to the panel) I don't anticipate this being a problem.  So the task of turning on the backlights seems simple enough.  Here are the problems and failed solutions I have tried:

The original inverter is remarkably flat  and specifically designed to fit in the monitor chassis. I have not been able to get consistent even lighting.  It does require a 24V line so I am using a separate DC line to power the 2 24V lines. As you can see I have gotten some response.  By giving 12V to the on/off it can become very bright.  But, this is neither stable nor even.  Without a doubt there is some way of mimicking the iMac's signal and use the native inverter.  But, I am not an electrical engineer and the entire purpose is to keep this as simple and stable as possible.  I have thus moved on in an attempt to find another solution.



Aftermarket inverter.  Available on ebay are several relatively cheap universal inverters that can support 6 ccfl lamps with a 4pin and 2 pin connectors.  This one was $30.  I'm not sure if the picture does it justice with the glare, but the screen is evenly lit and bright.  Whats more is that the connections are very simple.  There are two 12V rails, 2 grounds, one on/off - which takes 5V, and an adj/dimmer.  However, while much narrower, it is longer and more troubling, slightly thicker than the native iMac G4 inverter.


I thought it may be possible to make it fit in the case with some alteration using a multi-max dremel.  The back of the monitor housing uses "raised x's fit the monitor tightly.  I thought that by removing these raised areas I may be able to create a little more room for the thickness of the inverter.  As you can see below on one side the "Raised X" has been removed and sanded down (this does not damage the back or outward appearance at all).  I then placed the inverter in at several angles (to try I didn't use the protective plastic covering).

 As you can see it just doesn't fit .  I don't want to press down firmly, screw it in, and leave it under pressure.  I know it may not look like much but it extends around the entire side of the monitor.  As I was hoping to make this a touch screen as well, the monitor is likely to be somewhat unstable in the housing.  So I looked for other 6ccfl inverters that may be slightly thinner.

 Here are 5 inverters that are designed for 6ccfl monitors.  From top to bottom: an iMac G5 inverter, aftermarket on ebay (4pin/2pin), aftermarket on ebay (2pin x 3), a 20" apple cinema display inverter, and the aftermarket inverter used above.  The only one that the case would close with (even with the dremel modification) was the cinema display inverter.  However, it still took a little force and unlike every other inverter pictured, this is not a straightforward inverter (there are actually 8 pins - more than the iMac).

 I had also thought about using LED lighting (which does not require an inverter) however after a brief test of constructing my own led rail, I was not happy with the results (uneven lighting).  Putting the iMac's LCD onto a commercially manufactured  20" LED backlit montitor would likely work very well.  However, they simply do not manufacture 20" LED backlit LCD's in the 16:10 (1600x1050) orientation, which would be required for this mod.

So, I am left with 2 options: Continue to search for a solution to the 20" backlighting problem or to complete the all in one mod using the already built 17' monitor assembly.  I do have another idea for the 20", so I am not giving up yet.  After using my previous 17" mod for sometime, I do have to concede that a 17" monitor seems awfully small these days and a 20" would be preferable.  Plus, I have located a 5 wire resistive 20" touchscreen which would be ideal for this mod.  If anyone has any ideas, tips, or suggestions, they would certainly be appreciated.

17" Inverter Pinout/Instructions

To test pinouts I would recommend getting either a molex or sata to ac adapter such as this one:

By sacrificing an inexpensive molex splitter you get 2 12V, 2 5V, and 2 Grounds without having to deal with the hassle of an atx power supply.  It also comes with a handy on/off switch.  These are available from newegg for pretty cheap.  I would recommend getting an sata one if possible however, as that will give you a 3.3V line as well.

To get the 17" inverter to work you will need a source of power, the screen and inverter, as well as a couple 1Kohm resistors (mine were rated 1/2 watt).  Here is the pinout and connections on the right.

Interestingly I was unable to get the inverter to light without a resistor between the green and the 5V line.  I expected this with the purple, but not the green.  Also note that I am pretty certain the native power supply to the purple is actually 3.3V.  As it is simply an on/off I doubt the extra voltage will matter, but long term I can not say for sure.  If you have an sata power source you should try to use the 3.3V line and if it works I'd probably lean towards using the correct voltage.

As you can see I left the dimmer floating, there are various ways of making a dimmer, but it is not necessary as the backlights appear plenty bright by using this method.  Just as a reminder for those of you hooking up to a molex/sata power supply.  YELLOW = 12V, RED = 5V, BLACK = GROUND, GREY = 3.3V (only on sata).  There is also nothing wrong with using an atx power supply and its various voltages, I simply found this easier.

*NOTE: After hearing from a reader that the screen flickered with the Red line connected to 12V and stabilized when connected to 5V (and then confirmed by another reader) I decided to recheck it myself.  And 5V is indeed the correct voltage.  I then went and looked at my old notes which showed "Red - 5V".  I made an error when originally making this chart.  I apologize for any inconvenience and have updated the above chart.