GUIDE: Step by Step 17" iMac G4 TMDS to DVI Conversion - 800mhz and 1/1.25 Ghz Necks Completed

Mac Mini identifying monitor as "iMac"

This is a step-by-step detailing the process of converting a 17" iMac G4 to a useable LCD with a video cable that terminates with a DVI connector in the base.  I will focus only on the video connector and converting this LCD to be DVI compatible.  Please note that I am not starting from a complete machine.  I have several necks, empty domes/bases, and LCDs that I have obtained through various sources as individual parts.  So my tutorial will not focus on the general disassembly and reassembly, but on the wiring and powering of the LCD.


For those who have not followed my blog, please be aware that there are two versions of the wires in the 17" Mac G4 (Two different necks).  One version is for the 800mhz iMac, the other is for either the 1 or 1.25ghz iMac.  If you use the wrong one - the colors will not match up.  While the wires connect the same things, apple changed the color of some of the wires.  In addition, for the 1/1.25Ghz I have included a video tutorial to give another perspective. 


Note: Everything here is AT YOUR OWN RISK.  These mods will void your warranty and I provide absolutely no guarantee that you will have the same results as I have.  This is a financial risk, the parts that go into this are used and in some cases 10 years old.  Mistakes or even bad luck may result in no image or even permanent damage to components.  So know what you are getting into.  I can not vouch for the long term stability of this mod.  Although this mod is solder-less and simplified, obviously soldered, insulated connections are likely to be more stable.  Even though I have simplified the process, this is still an advanced mod.  Be cautious when handling live connections which (in the case of the inverter to backlight) can be several thousand volts.  So if you're still ready, lets get started:




I. PARTS LIST
These are the parts that I used or very common alternatives - MANY other variations are unquestionably possible, but I can not guarantee something I did not see work personally.  In some cases I will list where I purchased it from - this is in no way an endorsement of any particular merchant or sales site - just a statement of how I acquired it.


VIDEO TUTORIAL PART 1 (1/1.25Ghz NECK) can be seen here:
Introduction and Parts List

VIDEO TUTORIAL PART 2 (1/1.25Ghz NECK) can be seen here:
Parts List Continued

A) iMac G4 17" and components

1. Monitor Housing - 2 pieces (front and back) contains LCD and inverter



17" Inverter

2. Neck - while structurally the same the neck's of the 800mhz model has different colored wires than he 1ghz and 1.25ghz models.  As both pinouts are available it does not matter which you choose.



Faraday Cage

3. Dome - contains computer components (none of which are used), A white plastic overlay, a metal faraday cage (the metallic inner part of the dome), the bottom of the dome, and a circular tray for the bottom.

This is the hardest to buy.  You need a working LCD and Inverter for this mod.  As broken computers may or may not have functioning LCDs - its a tough choice. 

If possible, try not to buy and tear apart working machines - there are fewer and fewer of these available.  Ebay is littered with hundreds of broken machines and parts that can be recycled.  If the machine you buy is "dirty" - you can buy a new plastic outer housing for the dome.  If the screen or inverter doesn't work, they can also be found easily on ebay.

B) A Power Source - to power both inverter and LCD screen

Pico Power Supply

Any power source that has at least a DC: 12V and a 5V line will work, however addition of a 3.3V line actually matches up closer with the panels specs.  Despite this, I have not seen any problem with using only 12V and 5V.  As this makes everything more uniform and simpler, I am focusing on using these voltages via a standard molex connector.  Alternatives include any atx power supply with a molex. As there is limited space, you should choose a small power source like a pico power supply which is a DC-DC power source that uses an external power brick, but any atx power supply will work.  If you use an atx power supply you will have to "jump" it to get it to turn on without a motherboard.  This can be done by inserting a paper clip or wire between pins 14 and 15.  Simply put - grounding pin 14 turns on the power supply.

Rocker Switch

While this alone works you should think about putting some wire with an on/off switch between these.  Do not use a momentary switch, you need a real on/off (such as a rocker or toggle switch).

logicsupply.com has a nice selection of Pico Power Supplies, I'd probably recommend at least 120Watts.  Make sure you buy a DC-AC power brick as well.

Another option is a DC to molex power supply this gives the necessary 12V and 5V line and also connects to a regular AC plug.  This is what I am using for now.

Whatever you choose, it must simply have a working 4 pin molex plug.  My tutorial is based around using a working molex in combination with a molex splitter.  Cutting off the 2 female connectors and stripping the ends will give you 2 of each of these: 12V(Yellow), 5V(Red), Ground(Black).  Available from newegg.com.

Molex Splitter

Another possibility is using the native iMac G4 power supply.  As it has 3.3V, 5V, 12V, and Ground.  As readers have noted and I myself have tested for  the 20" this can work, but with some caveats.  I will post regarding the native PSU in the future.

C) Accessories and Cables

LVDS Cable

    1.  (Optional): Extra Small Wires and Pins. One source of extra wire is to buy LVDS cables (on ebay).  However, using wires with the proper pins will work best and it is difficult to be sure what size pins are in any given wire.  One source of iMac G4 wires is obviously an iMac G4.  Buying an extra neck as a source wires and pins may come in useful especially if you make a mistake.  These are always available on ebay and it does have to come from the same size iMac.  I used 3 small wires with pins from a 15" iMac G4 neck. (The neck does not have to be opened, I just cut off the last few inches) for the 800mhz version.

Alternatively you can use the wires in your own iMac's neck.  This will require cutting and stripping some small wires, but does work just as well.  Unless you have an extra neck or are concerned about making a mistake (once cut there is no going back), this is the method I would recommend as it saves having to purchase additional equipment.

    2.  Torx Screw driver kit or set, Philips screwdriver, Small Flat head screwdriver or mini screwdriver set.

    3.  Soldering iron and solder (not required but can be useful for making some connections more secure or for repairs).

    4.  A safety pin - for removing pins from connectors

    5.  Electrical Tape and/or heat shrink

Multimeter

    6.  A multimeter with continuity setting.  This is useful in checking the integrity of the connection especially if you are not getting an image

    7.  Alligator wires (at least 7).

A Stripped, Cut Cable

    8.  A Cable or connector for splicing.  This must be a TMDS cable such as DVI or HDMI.   Alternatives include:

          a) Cut DVI/HDMI cable: I do not recommend doing it this way.  It is easy to obtain and using a mutimeter, it is easy to find out which wires correspond to which pin.  But, the wires are difficult to work with and the solder itself can cause pixelation or "sparkles".  Simply put choice b below is much easier and likely to produce a better image.  If yo do proceed this way, after striping you will find the TMDS control wires (Clock, Data, Hot Plug, 5V) as well as 4 groups of wires that are further shielded.  These are the TMDS signal cables.  Each one of these has a positive wire, negative wire, and ground.  Also, remember when using a DVI cable the connector is MALE and this does not correlate directly to the standard diagrams and pin numbers which are based on a female connector.

DVI connectors (Female)

               b) A DVI connector (with small pins) - Although I'm sure similar ones exist.  The one I used is a right angle, female, digital only (no analog pins) dvi connector and the part number is:

MOLEX PN 74320-4004

I bought a bunch of these on ebay.  Other sources which I have personal experience with include Mouser.com which sells individual ones for under $5 and Digi-Key which sells individual one for under $4.  A search on google shopping or octopart shows Allied Electronics, Hawk Electronics, Heiland Electronics, RS Elecrtonics, Newark.com, and Onlineparts.com all stock this connector and sell it for $2 - $5 for one connector and less per unit if you buy multiples.

Octopart search
Google Shopping search

Item on:
Mouser
Digikey
Newark
OnlineComponents
Allied Electronics
RS Electronics

The advantages of this are many.  The pins can be pushed in, but if a mistake is made they can easily be removed.  No soldering of tiny wires is required and the connection quality will likely be better.  This is because the shorter the cable, the fewer the connections/solder points and the smaller the changes in resistance, the better the quality of the connection.  This also allows use of female connector (pin out is easier to follow).  It is very likely that other small pin DVI-D or DVI-I connectors will work, but I used this one and can therefore only vouch for this particular connector.  I have no special knowledge if other random connectors or part numbers will work.  Here are some data sheets on this connector if you want to compare it to another.

http://datasheet.octopart.com/74320-4004-Molex-datasheet-60256.pdf
http://datasheet.octopart.com/74320-4004-Molex-datasheet-62695.pdf
http://www.molex.com/pdm_docs/ps/PS-74320-001.pdf


I highly recommend this DVI connector it greatly simplifies the process and is much more stable.  I can not emphasize this enough.  My guide is based on this connector.

    9. At least two 1-Kohm resistors.  I used these from parts express via amazon.

  10. Wire cutters, strippers, and a scissor.
           
II. Disassembly

Courtesy of mrtotes

          - I have decided to skip a lengthy tutorial on disassembly.  Numerous tutorials exist on line for this.  Changing the hard drive requires near total disassembly.
Here is one tutorial for the hard drive:
 http://www.xlr8yourmac.com/systems/iMac_g4/imacg4_takeapart.html
And one teardown:
 http://68kmla.org/forums/viewtopic.php?f=13&t=13550

Briefly:
        - Using the torx screwdrivers open up the iMac's dome and remove the drive caddy which includes the hard drive and optical drive and set it to the side.  Physical removal of the fan, internal speaker, motherboard and power supply are not required and can either be done or left alone depending on what you plan to do with the iMac's base.

Inverter plug unhooked

Video cable unplugged

        -  Removal and isolation of 2 cables: the inverter and LCD is required.
Disconnect all cables.  I would recommend at least removing the drive caddy.  The rest is up to you.

Remove the black cover from the video cable with a flat head screwdriver and gently remove it from the motherboard.

Also remove the large plug which contains the cable labelled inverter

Using a safety pin lift up the black tabs

on the large inverter connector.  As the tabs are lifted gently pull each individual inverter pin free.

Video Tutorial Part 3: Freeing the Inverter Cables

Video Tutorial Part 4: Freeing the LCD Cables

For the iMacs LCD cable you must first remove the metal casing using a flat head screwdriver or x-acto knife.

- First pry open the top

- Then the side

- And then the metal cover should bend back and snap off

Pry open the top

Then the side

Peel Back and Snap Off

Exposed LCD Connecter

When the black is fully exposed you will again see little plastic tabs on the side.  Using a safety pin lift these tabs and push them down (its ok if they come off entirely).  You want to see the exposed metal from the pins where the tabs used to be.

When all tabs are done, VERY GENTLY pull the individual wires and pins free.

You may need to again use your safety pin to press down on the pin in the area where the tab used to be in order to help free it from the black connector.

NOTE: THE ENTIRE EASE OF THIS MOD IS DEPENDENT ON THE PRESERVATION OF THE WIRES WITH THEIR INDIVIDUAL PINS.  RIPING OFF EVEN ONE PIN FROM THE WIRE MAKES THIS MUCH MORE DIFFICULT.  USE MINIMAL FORCE AND TAKE YOUR TIME.














III. The Inverter


VIDEO TUTORIAL PART 5: HOOKING UP THE INVERTER

  - I recommend hooking up and verifying the inverter first.  This way you know right away if you need to replace your inverter.

  A)The pinouts

To the left are the pinouts for the inverters.  I had thought that  the 1/1.25ghz iMac used a neck that had an Orange Dimming wire in the inverter while the 800mhz had the off white.  However, on the neck I used here which was clearly an 800mhz neck, there was an orange dimmer wire.  While this does not matter (as both are left floating), it does mean that this is not a valid means of telling the different models apart.

I have altered these inverter pinouts to reflect the fact that they way we are using this there is no difference if the purple is hooked up or not, so I am now recommending leaving this wire floating.  I believe that the purple is likely involved in sleep with the iMac with with the way we are hooking it up it does not seem to matter.  The Green is likely a sleep-wake wire, as it will turn off when disconnected, but can not by itself turn back on.  The Red can turn the entire inverter on or off, as such (although this may not reflect its initial function), I have labeled this on/off.

* I have also differentiated between how we have the red hooked up when we want to test the backlights vs when we have our DVI source connected.

B) The molex splitter

1.  Take your molex splitter and cut off the two female connectors.

2  Strip the ends off:
      - 1 Yellow (12V)
      - 2 Red (5V)
      - 2 Black (Ground)
   2 Blacks and 1 Yellow can remain with no wire exposed

Molex Splitter To AC Power Source
(Note: I removed the extra black pin
but this is not necessary)

3. Connect the molex male end to the female molex of your power source which should be OFF

4.  Place Alligator Wires on
- Attach Yellow Alligator wire to one yellow molex wire (Note: I have two attached in the pic but you only need one)

- Attach Black Alligator wire to one black molex wire

- Attach Two Red Alligator wires to red molex wires (but on 1 wire attach sideways leaving end exposed for a second wire) as seen in picture.

- Attach one Green Alligator wire to end of the red molex wire. (Using Green simply helps telling the wires apart).

Alligator Wires to Molex (yellow is out of frame)

5. Take 2 1 Kohm resistors and twist one end onto the PURPLE and GREEN wires of the inverter cable

(Note: Purple does not appear to be necessary)

Resistors wrapped around Green and Purple pins

 

 6. Connect your alligator wires to the inverter pins

- Connect Yellow to Blue pin

- Connect either Red to Red

- Connect the other Red to the resistor wrapper around the Purple pin (Does Not appear to be necessary - Can leave floating)

- Connect Green to the resistor wrapped around the Green pin

- Connect Black to the Black pin

- Orange or White (depending on neck) inverter wire is not connected and left floating.

7. Turn on your power source.  The backlights should come on as seen below.  If so, turn off the power and continue on.  If not check your connections.

The backlights on

IV: The LCD Cable
- Be aware this will split into two different parts, one for the 800mhz iMac and one for the 1/1.25ghz.  If you do not know which one you have, see my two necks post.  The easiest (without disassembly of LCD) is to see if your black LCD cable contains a BROWN or ORANGE cable.  These will split into a red, green, black.  BROWN = 1/1.25ghz and ORANGE = 800mhz.


1. Grab your DVI connector and find a good DVI/TMDS pinout for reference in you get confused.  The one I have pictured below is courtesy of Tom's Hardware.   Just remember the numbers reflect a FEMALE DVI connector.  This is a digital only signal, so we will be using the areas highlighted a TMDS and also the control areas (labeled plug and play).  A TMDS data source actually contains 3 parts - POSITIVE, NEGATIVE, and GROUND.  DVI allows up to 7 of these (0,1,2,3,4, and Clock).  The iMac's LCD requires 4 (0,1,2, and Clock).  These correspond to the 4 colored wires that are in the iMac's black LCD cable.  And each one of these has 3 wires inside a red, green, and black.  This corresponds to the positive, negative, and ground signals respectively.

Courtesy of Tom's Hardware

2. Orient Yourself

FEMALE DVI CONNECTOR PIN NUMBERS

There are 3 Rows of 8 holes

The picture on the right is the front view
- The Top is recognizable as the "Analog Area" should be on the right when looking straight on.
- In addition, the connector is a parallelogram and the longer side is on top
- They are numbered left to right and the middle 2 rows are not used at all
- The Red boxes correspond to the pins for the TMDS signals (the pins in the iMac's black wire)
- The Green boxes correspond to the pins for the control (the pins in the iMac's gray wire)

Connector from top

As this is a right angle connector there are right angle pins visible on the top of the connector.  This then terminates in the male pins we will be using on the bottom.  See TOP VIEW

In the BOTTOM view below you can see that the top row pins (1-8) actually become the bottom row when looking at the pins from this angle.

The "Analog Area" will always be at the end.  So the closest pins to this area will be 8, 16, and 24 in the top, middle, and bottom rows respectively.

Bottom View of connector with"Free" iMac LCD cable.

LCD Cable with black heat shrink removed

3. Separate the Black and Gray iMac LCD wires

-  This gives you much more room to work with

-  Using a small scissor or wire clippers cut a small nick into the black heat shrink which envelopes both wires.

-  With your hands pull apart the sides of the heatshrik next to your cut.  It should pull apart easily.

-  Underneath is a piece of gray cloth tape, unravel this until the wires come apart



THIS GUIDE NOW DIVIDES


THE RED BELOW WILL BE FOR THE 17" iMAC G4 - 800Mhz VERSION / NECK


THE BLUE FURTHER DOWN WILL BE FOR THE iMAC G4 1 or 1.25 Ghz VERSION / NECK (VIDEO TUTORIAL)


The 800mhz Neck:


4.  The Pinout


Review this pinout for reference.  This tells you which color wire and female pin (left column) will be pushed into which male pin on the DVI connector (right column).  In the middle is a description of the wires function.

800 mhz 17" iMac G4 pinout

5.  The TMDS Signal - The Black LCD Cable


A) THE RED WIRE

- Locate the RED wire from the black cable and identify the 3 wires that come from this cable.  The Green, Red, and Black.

Red Wire - Connecting Data Cable #2 (Pins 1, 2, and 3)

- This is the Data #2 Cable
-  Of note is that the small green cables will always be negative and the small red cables positive.  The Black is the shield or ground.
- Locate Pins: 1, 2, and 3 on the connector
- With the actual DVI part face down, find the pin furthest away from the "Analog Area" and on the row closest/top row.  This is PIN #1


i) Take your Red to Green wire
- Using your fingers position the female pin with the "seam" facing either up or down (towards the Front to back of the connector).
- DO NOT PUSH IT IN SIDEWAYS.
- Using very gentle force slide the Green wire on to PIN #1.  You can press until to reach the plastic of the connector.
-  Do not push against significant resistance.  The pin should fit easily and securely.
- Once in place it should hold fairly firmly.


ii) Take your Red to Red wire and push it into position #2 next to the green wire.


iii) Take your Red to Black/Shield and push it into position #3 next to the red wire.

B) The Orange Wire
- The is Data Cable #1
- Locate Pins 9, 10, and 11
- These are the middle row pins in the same column as the Red wire you just placed.


i) In the middle row, right in front of the Red to Green pin, furthest from the analog area, place your Orange to Green Pin - Position #9


ii) Next to this in Position #10 (in front of the Red to Red), place your Orange to Red pin.


iii) Finally in Position #11 (in front of the Red Shield/Ground), push the Orange Shield/Ground into place.

Orange Cables Pins Directly in Front of Red Cables Pins

RED, ORANGE, and BLUE Connected

C) The Blue Wire


- This is Data Cable #0
- Locate Pins 17, 18, and 19
- These are the top row pins (bottom view) just above the orange pins you just placed.

i) In the top row (the blue square), right in front of the Orange to Green pin, furthest from the analog area, place your Blue to Green Pin - Position #17

ii) Next to this in Position #18 (in front of the Orange to Red), place your Blue to Red pin.

iii) Finally in Position #19 (in front of the Orange Shield/Ground), push the Blue Shield/Ground into place.

D) The Green Wire

- This is the Data Cable - Clock

The Green Wire (Notice how its the mirror image)
Small Green Always on the outside
Shield/Black in the Center

- Locate the Pins #22, 23, and 24

- These pins are the last 3 in the row, closest to the Analog Area.  They are in the same row as the pins from the BLUE WIRE you just placed.  The row closest to the DVI interface.

-  NOTE THAT THE ORDER OF PINS IS DIFFERENT FOR THIS WIRE

          PREVIOUSLY ALL PINS WENT GREEN, RED, SHIELD FOR THE GREEN IT IS REVERSED.  IT GOES SHIELD, RED, GREEN

          THINK OF IT AS THIS, GREEN IS ALWAYS ON THE OUTSIDE, SHIELD ON THE INSIDE.

          SO FOR THIS WIRE WE WILL PLACE THEM GOING RIGHT TO LEFT

i) In the top row, same row as the Blue Wire, closest to the analog area (the last pin in the row), place your Green to Green Pin - Position #24

ii) Next to this in Position (going right to left) #23 (same row as Blue), place your Green to Red pin.

iii) Finally in Position #22 (same row as Blue), push the Green Shield/Ground into place.

Completed Top View

Completed Front View
Green Wire's Pins in Foreground on Left
Blue Wire's Pins in Foreground on Right

6.  THE GRAY LCD CABLE
- Of the Nine Colored Wires inside the Gray LCD Cable, only 3 of them actually connect to the DVI connector (Red, White and Black).  The other 6 connect to either 5V or Ground


THE POWER SOURCE:
A) The 5V Cables
-  Grab your Gray LCD Cable
-  Separate Out the Blue, Orange, and Yellow
-  Take a RED alligator Wire and place these 3 pins securely within its teeth

BLUE, ORANGE, and YELLOW to 5V

B) The Grounds

- Do the exact same thing for the 3 Grounds:

- Separate out the Gray, Purple, and Green Wires from the Gray LCD Cable

- Take a Black alligator Wire and place these 3 pins securely within its teeth

On Left: BLACK ALLIGATOR (Purple, Grey, Green)
On Right: RED ALLIGATOR (Yellow, Blue, Orange)

C) Connect to Power Source

- Looking Back at your power source, at one 5V RED MOLEX wire add the RED Alligator from the Gray LCD cable.

- For the Ground connect it to the unused Black Molex Wire.  The other black cable should be attached to an alligator wire going to the Black Pin/Wire on the Inverter Cable.

7. THE TMDS CONTROL WIRES (VEDID, GROUND, and HOT PLUG)


*IN THIS VERSION I USED WIRES WITH PINS FROM AN EXTRA iMAC NECK.  IF YOU DON'T HAVE OR WISH TO USE AN EXTRA NECK, YOU CAN CUT SOME WIRES WITH PINS FROM THIS iMAC NECK ITSELF.  ALTHOUGH SOMEWHAT RISKIER, THIS WORKS JUST AS WELL AS SAVES HAVING TO BUY AN ADDITIONAL NECK.  I COVER HOW TO DO THIS BELOW, BUT FEEL FREE TO SEE THIS PART OF THE GUIDE IN THE BLUE SECTION (1/1.25GHZ NECK), IN WHICH I INCORPORATE THIS METHOD.


- These 3 Wires will Plug into Pins 14, 15, and 16, respectively.  This is the Middle Row of Pins directly behind the 3 pins from the Green Wire on the Black LCD Cable.
- Only 3 wires from the iMacs LCD cable remain unused.
- However there are a Total of 5 TMDS Control Pins, only 3 come from the iMac's wires, for the 3 listed above we will need extra small gauge wire, similar to the wires on the iMac's Gray LCD cable.
- For this part really some small gauge (about 24 - 28) wires.  3 wires should include pins that can plug into the DVI connector.  Since the only pins I can verify that do this are the iMac G4's neck pins, an extra neck is needed for this method.
- Note: This is probably the trickiest part.


A) Prepare your extra wires
- Method #1: Using wires from only one neck:

Peel back the Gray LCD cable's Plastic and Shielding about 16cm.  Isolate the Ground Wires: PURPLE, GREEN, and GRAY. (You can use the 5V wires as well, but I would feel safer cutting the grounds).  Cut these three wires at about 3 - 4 inches.  Make sure you leave enough wire remaining so that it can be easily stripped.

Insulation seen after shielding removed.

*Note these pics reflect an extra damaged iMac cable I had.  I used wires from an extra iMac G4 neck for this mod, but again, I did use this method for the 17" 1/1.25 Ghz Guide.

Shielding and Insulation Peeled Back

Take the now cut ends of the PURPLE, GREEN, and GRAY wires in the Gray LCD cable and strip the last few centimeters of each of these wires so that each now has exposed wire at the end.  Twist these 3 wires together.  You can now hook this up to an alligator wire or a different wire and hook it back up to the Molex's Black/ground wire.

We now have 3 wires, although not needed a 4th is helpful for connecting, any small gauze wire can be used from any source.  You use an extra cable such as the iMac's speaker or fan wires or an LVDS cable with or without a male pin on the end (a male pins allows you to plug not the female pin of the iMac's cable, but you can just as easily strip the wire and wrap it around this pin).

- Method #2: Using wires from an extra neck:

Cables from the LCD connector of a 15" iMac G4

I used 1 cable from an LVDS cable (my optional 4th wire) and 3 with pins from the neck of an iMac G4 15".  The same method as above is applied, the shielding and insulation are peeled back from the LCD wire on the dome side of the extra neck.  3 - 4" of 3 wires are cut and the non-pin ends are stripped.

The wires from 15" iMac neck with pins on

B) The 1st Extra Wire - TMDS CONTROL GROUND


i) Take one wire with a pin on it - I USED A GREEN COLORED WIRE - but it does not matter what color you use, just remember what it is.  Strip the non-pin end of the wire.


- I am going to recommend a small wire stripper, but to be honest, I usually use (against all dental recommendations) the bite and pull method.

One wire with pin on one end, stripped on other

ii) Wrap the stripped end around the your neck's LCD Ground wires: the Green, Grey, and Purple Grounds from the Gray LCD cable that is currently connected to a Black Alligator Wire which connects to the Black Molex Wire (The Ground).  You can also use other grounds, it does not matter, but this is likely the easiest.  So now 4 wires total are in the teeth of this alligator wire.  [If you used Method #1 and cut your own neck wires you will now note that you are in essence wrapping the cut wire back from once it was cut, however, this wire will now used to ground the DVI itself].

Alligator wire with "Extra" Green Wire wrapped around

iii) Place the Pin from this Wire into Position #15 on your DVI Connector
- This is in the Middle Row, the last pin from the end (by the Analog Area)
- This pin gets placed directly behind the RED pin from the GREEN wire of the BLACK LCD cable (the last colored wire we placed).

Ground Wire to DVI Connector #15

C) The Second and Third Extra Wires - TMDS Control Voltage (VEDID) and Hot Plug


Some quick background: 
- An oversimplification, but, the DVI source (the computer) actually has a pin that sends a 3.3V signal to the LCD that tells it to turn on.  This is how the image turns off when the computer tells the monitor to sleep.  In addition, the LCD itself sends a low voltage in THE OTHER DIRECTION, back to the DVI source (the computer).  This lets the computer know that there is something connected to this port.


- The voltage sent from computer to LCD (the LCD's on/off) is called the VEDID and this is Pin #14 on the DVI and connects to the Red (looks somewhat "Hot Pink") wire in the Gray LCD cable where its transmitted to the LCD itself.


- The voltage sent from the LCD to the computer is called the "HOT PLUG DETECT".  This signal is supposed to come from the LCD and plug into Pin #16 on the DVI Connector.  However, this monitor was  designed to always be connected.  So, the iMac's LCD does not have a wire that corresponds to the Hot Plug Detect.  To "fool" the computer we can give its own signal right back to itself.  However, we need to add resistance by adding a 1-Kohm resistor.

3 Extra Wires and Resistor

i) Get Prepared


     a) Take Your "2nd Extra Wire" with Female Pin,  cut and strip the end, but strip off a large segment of the end without the pin.  I used another wire from my extra 15" iMac neck, with a female pin, Method #2.  My wire is recognizable as the Red with Black Stripe.  This wire will be the VEDID and will connect to Pin #14 on the DVI Connector


    b) Take Your "3rd Extra Wire" with Female Pin, repeat as above.  Although you don't need to strip off quite as much.  This wire is recognizable as an Orange with Blue Stripe.  This wire will be the HOT PLUG DETECT and will connect to Pin #16 on the DVI Connector.


    c) (Optional) Although not necessary, one additional wire helps, it can have either a male pin or no pin at all.  I took this wire from an extra LVDS cable.  But having no pin and simply being stripped on both ends will work fine.  This wire can be short (2").  This is a plain RED wire with a male pin on the end.


    d) A 1 Kohm resistor


ii) Create Your HOT PLUG and VEDID

Extra wire wrapped around 1st part of strip

- So you should have 3 wires


    1) VEDID - Wire with female pin at one end and a long section of stripped/exposed wire at the other end - MINE IS RED WITH BLACK STRIPE


    2) HOT PLUG - Wire with female pin at one end and a short section of stripped/exposed wire at the other end - MINE IS ORANGE WITH BLUE STRIPE


    3) EXTRA WIRE (Optional) - Short Wire with either male pin or short strip/exposed wire at one end and short strip/exposed wire at the other end. MINE IS A PLAIN RED WIRE


-Wrap the non-pin/stripped half of the Red with Black Stripe Wire / The VEDID around either the hot pink/red wire's pin from the iMac's Gray LCD cable (if you do not want to use the optional extra wire) or the non-pin/stripped end of your optional extra wire - Plain Red, BUT LEAVE SEVERAL centimeters of stripped wire from the VEDID sticking out as seen in the picture.


- Wrap the 2nd part of the VEDID's strip (the part left sticking out above) around the 1 Kohm Resistor


- Wrap the Stripped end of the Hot Plug Cable (ORANGE WITH BLUE STRIPE) around the other end of the resistor.

Completed VEDID and HOT PLUG Cable

Completed Cable View #2

Again, what you see above is simply a split.  The voltage goes from the computer through the DVI connector to the VEDID (Red with Black Stripe Wire via Pin#14).  It then splits into two.  One signal sends the original 3.3V via the "Plain Red Wire" to the Red/Hot Pink wire (or directly to the Hot Pink if you did not use the extra wire) of the Gray LCD cable, which carries this to the LCD to turn it on.  The second split sends the 3.3V from the VEDID to the 1Kohm Resistor and connects back to the DVI connector via the HOT PLUG (Orange with Blue Stripe via Pin #16).  Thus, going through the DVI connector to "fool" the source.




- If you used the extra wire, wrap the Resistor and exposed splice with electrical tape.  If you did not, you will need to leave the splice connection exposed to add another splice with the Red inverter wire as noted if part D below.

Resistor wrapped in Electrical Tape

VEDID (#14) and HOT PLUG (#16) surround
GROUND (#15)

iii) Plug the VEDID to Pin #14
- This pin is in the middle row, next to the the Ground wire that was just placed.
-  It is 3 pins from the "Analog Area" at the end
- When looking at the connector from the front (DVI interface facing you), this pin is directly behind the the Black/Shield from the Green Wire of the the Black LCD Cable.


iv) Plug the HOT PLUG DETECT to Pin #16

- This pin is in the middle row, on the other side of the Ground wire that was just placed.

-  It is the last pin of the row and is next to the "Analog Area" at the end

- When looking at the connector from the front (DVI interface facing you), this pin is directly behind the the Green from the Green Wire of the the Black LCD Cable.

v) Connect to iMac's LCD Cable
- If you did not use an extra wire this step is already done, as the first part of the VEDID is already connected to the Hot Pink/Red wire of the Gray LCD cable.  However, as you can see the extra wire gives us some extra room and flexibility and also gives us an extra connection.  This will come in useful later, because we will splice/split this 3.3V source again to use with the inverter at the end of this mod.
- You should have 2 of the 3 ends plugged into the DVI.  This leaves the one remaining short "extra cable".  I've been using the plain Red wire with a male pin.


- Take this end (if you used a cable with a male pin) and plug this male pin into the female pin on the Red (somewhat Hot Pink appearing) wire from the iMac G4's Gray LCD cable.  If there is no male pin simply strip this end and wrap it around this pin.


- There should only be 3 wires left unhooked on the Gray cable: White, Black, and Red(Hot Pink).  So, it should be easy to identify.

VEDID (Pin#14) to iMac's Gray LCD Cable - Red Wire

D) Adding Inverter Control

"The Connection" where we connect our Red Inverter Wire

- As configured the backlights will stay on during sleep as there is no signal to turn them off.  In addition, the may not come on at all when you turn on the computer.  One way to get the backlights to turn on and off with the display is to connect them to the Voltage from the Computer/DVI: The VEDID.  In effect we are taking the VEDID power source from the DVI and splitting it again (3 splits - 1 for the hot plug, 1 for the hot pink/red wire to turn on the LCD, and now 1 for the red inverter wire to turn on the backlights).  But, with the extra cable we actually split it, then split one side again.

- Take the Alligator Wire that connects to the RED INVERTER WIRE.  And Unhook the other end that is currently connected to the Red Molex 5V line.

- Take this end and clamp its teeth around the Connection (seen in picture above) between the iMac Gray Cable's Red/Hot Pink Wire and the spliced VEDID "Extra Wire".  

- If you did not use the optional wire you must add the alligator wire to the VEDID splice itself, and make it a true three way split.  This must be on the pin#14 side before the resistor.

E) TMDS Control - Clock and Data (White and Black)

Clock and Data (White and Black) to DVI #6 and 7

- 2 wires from the iMac's Gray LCD cable should still be unhooked at this point


i) Connect "White - CLOCK" to DVI Connector Pin #6
- This is in the same Row as the Black LCD Cable's RED wires but the third pin from the end / "Analog Area"
- This pin is right behind (when facing the DVI interface) the VEDID placed in the previous step.


ii) Connect "Black - DATA" to DVI Connector Pin #7

- This is in the same Row as the Black LCD Cable's RED wires but the second pin from the end / "Analog Area"

- This pin is right behind (when facing the DVI interface) the GROUND placed in the previous step.

*Please Note that these pins are reversed in the 1/1.25Ghz Neck, so do not get confused when looking at the video or the 1/1.25 guide below.

F) Connect a DVI Cable to your DVI interface - Connect the other end of the DVI cable to a source/Computer and Turn on your Power Source.  Then power on your computer or DVI source.

- You should see the image.
- Complete this mod in whatever way you see fit.  For all-in-one recommendations see my 20" Guide.

Completed TMDS to DVI.

The 1 or 1.25Ghz Neck

4.  The Pinout

Review this pinout for reference.  This tells you which color wire and female pin (left column) will be pushed into which male pin on the DVI connector (right column).  In the middle is a description of the wires function.

Important Note: This color scheme represents every 1/1.25Ghz neck I have come across except one.   During my tutorial there was a variation in the neck I used.  Because this neck was a refurbished product, I doubt too many others will have this variation, but please be aware of it.  The Black LCD cables Red wires are replaced by gray/off white white wires.  So there is a Brown, Blue, Green, and Gray (NOT RED).  SO TMDS pin numbers 12,13, and 14 are a gray wire, not red in my tutorial, but they should be RED for most everyone.  In addition, the smaller red wires that come from the Brown, Blue, Green, and Red/Gray Wires are also Gray.  So a shield, green, and Gray wire are seen.  SO TMDS pin #3 is Brown to Gray, #6 Blue to Gray, #9 Green to Gray, and #12 Gray to Gray.  Simply RED = GRAY for the Black LCD cable.  I will keep noting this during the tutorial.

As to not just repeat the above with slight variation, I have composed a video tutorial.  The first parts including the parts list and inverter can be found in the sections above, I start here with the 

5.  The TMDS Signal - The Black LCD Cable

VIDEO TUTORIAL PART 6: The Black LCD Cable

A) THE BROWN WIRE

THE BROWN WIRE to DVI

- Locate the BROWN wire from the black cable and identify the 3 wires that come from this cable.  The Green, Red (in my case Gray), and Black/Shield.

- This is the Data #2 Cable

-  Of note is that the small green cables will always be negative and the small red (or gray) cables positive.  The Black is the shield or ground.

- Locate Pins: 1, 2, and 3 on the connector

- With the actual DVI part face down, find the pin furthest away from the "Analog Area" and on the row closest/top row.  This is PIN #1

  i) Take your BROWN to Green wire

        - Using your fingers position the female pin with the "seam" facing either up or down (towards the Front to back of the connector).

        - TRY NOT PUSH IT IN SIDEWAYS.

        - Using very gentle force slide the Green wire on to PIN #1.  You can press until to reach the plastic of the connector.

        -  Do not push against significant resistance.  The pin should fit easily and securely.

        -  Once in place it should hold fairly firmly.

  ii) Take your BROWN to Red (Gray on mine) wire and push it into position #2 next to the green wire.

  iii) Take your BROWN to Black/Shield and push it into position #3 next to the red (Gray on mine) wire.

B) The BLUE Wire

THE BLUE WIRE to DVI

- The is Data Cable #1

- Locate Pins 9, 10, and 11

- These are the middle row pins in the same column as the BROWN wire you just placed.

   i) In the middle row, right in front of the BROWN to Green pin, furthest from the analog area, place your BLUE to Green Pin - Position #9

   ii) Next to this in Position #10 (in front of the BROWN to Red(Gray on Mine)), place your BLUE to Red (Gray on mine) pin.

   iii) Finally in Position #11 (in front of the BROWN Shield/Ground), push the BLUE Shield/Ground into place.

C) The GREEN Wire

THE GREEN WIRE to DVI

- This is Data Cable #0

- Locate Pins 17, 18, and 19

- These are the top row pins (bottom view) just above the BLUE wire pins you just placed.

i) In the top row, right in front of the BLUE to Green pin, furthest from the analog area, place your GREEN to Green Pin - Position #17

ii) Next to this in Position #18 (in front of the BLUE to Red (Gray on Mine)), place your GREEN to Red (Gray on Mine) pin.

iii) Finally in Position #19 (in front of the BLUE Shield/Ground), push the GREEN Shield/Ground into place.

D) The RED (GRAY on mine) Wire

***Again Please Note That My Refurbished Neck Used A Gray/Off-White Color Wire instead of a Red Color (Use Your imagination and Pretend its Red in Color for your mod).  

- This is the Data Cable - Clock

- Locate the Pins #22, 23, and 24

- These pins are the last 3 in the row, closest to the Analog Area.  They are in the same row as the pins from the GREEN WIRE you just placed.  The row closest to the DVI interface.

-  NOTE THAT THE ORDER OF THE SMALL PINS IS DIFFERENT FOR THIS WIRE

          PREVIOUSLY ALL PINS WENT GREEN, RED, SHIELD FOR THIS WIRE IT IS REVERSED.  IT GOES SHIELD, RED, GREEN

          THINK OF IT AS THIS, THE SMALL GREEN IS ALWAYS ON THE OUTSIDE, SHIELD ON THE INSIDE.

          SO FOR THIS WIRE WE WILL PLACE THEM GOING RIGHT TO LEFT

i) In the top row, same row as the GREEN Wire, closest to the analog area (the last pin in the row), place your RED (GRAY on mine) to Green Pin - Position #24

ii) Next to this in Position (going right to left) #23, place your RED to Red pin (GRAY to Gray on mine).

iii) Finally in Position #22 (same row as GREEN), push the RED (Gray on Mine) Shield/Ground into place

The RED/GRAY WIRE to DVI (Top Column on Right of DVI)

6.  THE GRAY LCD CABLE


Video Tutorial Part 7: The Gray LCD Cable

Video Tutorial Part 8" The Gray LCD Cable Continued

- Of the Nine Colored Wires inside the Gray LCD Cable, only 3 of them actually connect to the DVI connector (Red, White and Black).  The other 6 connect to either 5V or Ground

Overview

A) The 5V Cables

-  Grab your Gray LCD Cable

-  Separate Out the Purple, Orange, and Yellow

-  Take a RED alligator Wire and place these 3 pins securely within its teeth
-  Connect the other end of the Alligator Wire to the RED 5V Molex Power Wire

The 5V LCD Wires Connect to 5V Molex

B) THE TMDS CONTROL WIRES (VEDID, GROUND, and HOT PLUG)

*IN THIS VERSION I USED WIRES WITH AND WITHOUT PINS FROM THIS iMAC NECK ITSELF EXCLUSIVELY.  ALTHOUGH SOMEWHAT RISKIER, THIS WORKS JUST AS WELL AS SAVES HAVING TO BUY AN ADDITIONAL NECK.  I COVER HOW TO USE WIRES FROM AN EXTRA NECK IN THE RED SECTION (800Mhz NECK) ABOVE.

- These 3 Wires will Plug into Pins 14, 15, and 16, respectively.  This is the Middle Row of Pins directly behind the 3 pins from the RED Wire (GRAY on Mine) from the Black LCD Cable.

- There are a Total of 5 TMDS Control Pins, only 3 come from the iMac's wires, for the 3 listed above we will need extra small gauge wire, similar to the wires on the iMac's Gray LCD cable.

- For this part we need 3 wires which should include pins that can plug into the DVI connector.  Since the only pins I can verify that do this are the iMac G4's neck pins, we will cut off wires with pins from the iMac's Gray LCD Cable that do not need this pins.

1) Prepare your extra wires

- Using wires from only one neck:

Shielding removed with insulation exposed

Peel back the Gray LCD cable's Plastic and Shielding about 4".  Isolate the Ground Wires: BLUE, GREEN, and GRAY. (You can use the 5V wires as well, but I feel safer cutting the grounds).  Cut these three wires at about 3 - 4 inches.  Make sure you leave enough wire remaining so that it can be easily stripped.

Ground wires cut and both sides of cut stripped

Take the now cut ends of the BLUE, GREEN, and GRAY wires in the Gray LCD cable and strip the last few centimeters of each of these wires so that each now has exposed wire at the end.  Twist these 3 wires together.  You will eventually hook this up to an alligator wire or a different wire and hook it back up to the Molex's Black/ground wire.

We now have 3 "extra" wires with female pins, although not needed, a 4th is helpful for connecting, any small gauge wire can be used from any source.  You use an extra cable such as the iMac's speaker or fan wires which is what I used (extra black speaker wire).

Speaker wire from iMac G4 connector

Gray Wire Twisted onto Grounds

2) The 1st Extra Wire - TMDS CONTROL GROUND

i) Take one cut wire with a pin on it - I USED THE GRAY WIRE - but it does not matter what color you use, just remember what it is.  Strip the non-pin end of the wire.

- I am going to recommend a small wire stripper, but to be honest, I usually use (against all dental recommendations) the bite and pull method. 

- Take the 3 remaining ends of the Grounds (Blue, Gray, and Green) strip them and twist them together as noted above.  Take the cut Gray wire, strip the non-pin end and twist it back onto the ground wires from where it was cut.  However, do so with the wire oriented in the other direction so the connection forms a V as seen in the picture.  This V will eventually connect to a Black Alligator Wire and then connect to the Black Molex Ground.  You can either hook this up now or later.

3) The Second and Third Extra Wires - TMDS Control Voltage (VEDID and Hot Plug)

Some quick background: 

- An oversimplification, but, the DVI source (the computer) actually has a pin that sends a 3.3V signal to the LCD that tells it to turn on.  This is how the image turns off when the computer tells the monitor to sleep.  In addition, the LCD itself sends a low voltage in THE OTHER DIRECTION, back to the DVI source (the computer).  This lets the computer know that there is something connected to this port.

- The voltage sent from computer to LCD (the LCD's on/off) is called the VEDID and this is Pin #14 on the DVI and connects to the Red (looks somewhat "Hot Pink") wire in the Gray LCD cable where its transmitted to the LCD itself.

- The voltage sent from the LCD to the computer is called the "HOT PLUG DETECT".  This signal is supposed to come from the LCD and plug into Pin #16 on the DVI Connector.  However, this monitor was  designed to always be connected.  So, the iMac's LCD does not have a wire that corresponds to the Hot Plug Detect.  To "fool" the computer we can give its own signal right back to itself.  However, we need to add resistance by adding a 1-Kohm resistor. 

 i) Get Prepared

    a) Take Your "2nd Extra Wire" with Female Pin,  cut and strip the end, without the pin.  I used the GREEN wire.  This wire will be the VEDID and will connect to Pin #14 on the DVI Connector

    b) Take Your "3rd Extra Wire" with Female Pin, repeat as above.  I used the remaining BLUE wire.  This wire will be the HOT PLUG DETECT and will connect to Pin #16 on the DVI Connector.

Black "Optional" Wire to Resistor

    c) (Optional) Although not necessary, one additional wire helps.  I harvested this from the black wire of the iMac G4's speaker cable.  This is a BLACK wire, which you should strip on both ends.

    d) A 1 Kohm resistor.  Take one stripped end of the "optional" BLACK wire and wrap it around the 1 Kohm resistor.

    e) The Hot Pink/Red wire with female pin which remains connected via the iMac G4's Gray LCD cable. 

The wires: Hot Pink/Red (Top), Hot Plug - Blue (Left),
VEDID - Green (Middle), and Black with resistor (Right)

 ii) Create Your HOT PLUG and VEDID

Schematic

-Wrap the non-pin/stripped half of the GREEN Wire / The VEDID around the hot pink/red wire's pin from the iMac's Gray LCD cable.

Hot Pink to Green 

- Wrap the non resistor end of our optional BLACK wire around the Hot Pink - Green Wire connection just made above.  If you did not want to use an optional wire, instead use the 1 Kohm Resistor itself to wrap around.

Add Black to Resistor Wire to complete the split

- Wrap the Stripped (non-pin) end of the Hot Plug Cable (BLUE WIRE) around the other end of the resistor.

Attach Blue to other and of Resistor

- Completed VEDID and HOT PLUG splice

Completed

C) The GROUNDS

- Grab the remaining split and twisted ends of the cut ground wires (Blue, Green, and Gray) + the other part of the cut Gray which have been twisted into a "V"

- Take a Black Alligator Wire and Clip it onto the bottom point of the V, so that all (now 4) wires are contacted.

- Then connect the other end of the Black Alligator onto the Black Molex/Ground Wire.

Grounds (3+1) to Black Molex

D) Connecting our 3 Pins to the DVI

Again, what you see above is simply a split.  The voltage goes from the computer through the DVI connector to the VEDID (GREEN via Pin#14).  It then splits into two.  One signal sends the original 3.3V via the Hot Pink of the Gray LCD cable to the LCD to turn it on.  The second split sends the 3.3V from the VEDID to the 1Kohm Resistor and connects back to the DVI connector via the HOT PLUG (BLUE via Pin #16).  Thus, going through the DVI connector to "fool" the source.

i) Plug the VEDID (The GREEN Wire) to DVI Pin #14

- This pin is in the middle row, the same as the triplet wires from the Black LCD Cable's BLUE wire.

-  It is 3 pins from the "Analog Area" at the end

The Green Wire's Pin of our splice to DVI Pin #14

ii) Plug the GROUND (The GRAY Wire) to DVI Pin #15

- This is again in the Middle Row, the next to last pin from the end (by the Analog Area)

- This pin gets placed right next to the VEDID we just placed, one closer to the Analog Area

The Gray Wire's Pin of our splice to DVI Pin #15

iii) Plug the HOT PLUG DETECT (The BLUE Wire) to DVI Pin #16

- This pin is in the middle row, next to the Ground wire that was just placed.

-  It is the last pin of the row and is next to the "Analog Area" at the end

The Blue Wire's Pin of our splice to Pin #16

E) TMDS Control - Clock and Data (Black and White)

The BLACK - CLOCK and WHITE - DATA
to DVI Pins #6 and 7

- 2 wires from the iMac's Gray LCD cable should still be unhooked at this point

i) Connect the BLACK wire's pin - "CLOCK" to DVI Connector Pin #6

- This is in the same Row as the Black LCD Cable's BROWN wires but the third pin from the end / "Analog Area"

- This pin is right behind the VEDID (Our GREEN spliced wire) placed in the previous step.

ii) Connect the WHITE wire's pin "DATA" to DVI Connector Pin #7

- This is in the same Row as the Black LCD Cable's RED wires but the second pin from the end / "Analog Area"

- This pin is right behind GROUND (Our GRAY spliced wire) placed in the previous step.

- Pin 8 (Behind the BLUE HOT PLUG DETECT) is left unconnected.

*Please Note that these pins are reversed in the 800mhz Neck, so do not get confused when looking at the 800mhz guide above.

F) Adding INVERTER CONTROL

Video Tutorial Part 9: Inverter Control and Demonstration

- As configured the backlights will stay on during sleep as there is no signal to turn them off.  In addition, the may not come on at all when you turn on the computer.  One way to get the backlights to turn on and off with the display is to connect them to the Voltage from the Computer/DVI: The VEDID.  In effect we are taking the VEDID power source from the DVI and splitting it again (3 splits - 1 for the hot plug, 1 for the hot pink/red wire to turn on the LCD, and now 1 for the red inverter wire to turn on the backlights).  But, with the extra cable we actually split it, then split one side again.

i) Take the Alligator Wire that connects to the RED INVERTER WIRE.  And Unhook the other end that is currently connected to the Red Molex 5V line.

- Take this end and clamp its teeth around the one of two places:

Choice 1:

On the split from the spliced VEDID (GREEN) to the iMac Gray Cable's Red/Hot Pink Wire and the "Optional" Black Wire.  If you did not use the optional wire, the resistor itself will be connected here.  Thus creating a 3 way split from the VEDID.

#1: From RED inverter to the VEDID Split

Choice #2:

By using the optional Black Wire you get an additional "splice point".  You can connect the Red Alligator Wire to the interface between the Black Wire and the Resistor.  This must be on the Black wire's side of the resistor (BEFORE THE RESISTOR).  The other side where the BLUE Wire connects then goes to DVI Pin #16 CAN NOT BE USED.  This is the same effect as Choice 1, but instead of a three way split, there is now a split and then 1 side is split again.

#2: From RED inverter to the "Optional" Black Wire
and Resistor Interface

F) Connect a DVI Cable to your DVI interface - Connect the other end of the DVI cable to a source/Computer and Turn on your Power Source.  Then power on your computer or DVI source.

- You should see the image.

- Complete this mod in whatever way you see fit.  For all-in-one recommendations see my 20" Guide.

Mac Mini's image to iMac G4's 17" LCD via the neck

I have put quite a bit of time and energy into this guide.  Constructive Criticism on things that are unclear or can be shown in a better or different way is actually appreciated.  I am confident that people of many different skill levels can pull this off, but it is by no means easy.

I hope this guide has helped.  As always comments, suggestions, and questions are appreciated and welcomed.

Good Luck and Thanks for reading!