A Genuine iMac G4 All-In-One

Although I thought the previous 20" iMac G4 / Apple Cinema Display came out very well and it has become my most frequently used desktop, there were compromises that I had to make.  The two biggest ones were externalizing the computer (abandoning the all-in-one concept) and using the external housing of the apple cinema display.  While I think it looks good, it still is not the classic 20" iMac G4.  While working on a different mod, I realized there are two things I overlooked while designing and building the previous mod that would allow a genuine 20" iMac G4 all-in-one with an updated intel processor.

I was working on a project which involved using some of my spare components with a broken shell of an iMac G5.  These were mostly unused pieces from my iMac G4 mod.  This predominantly included a LG LM201W03 monitor from an apple cinema display (although the G5 I believe uses the same panel with some variations).   And the ECX board which uses a P8700 Penryn Core 2 Duo processor (the current mac mini uses the P8600).

Comparison of native iMacs DVD/HD to size of Bluray with ECX board

As it is the size of a 3.5" drive and it has its own  Compact Flash slot to use as a SSD, I had hoped to slot this into the G4 in place of the existing hard drive and create an all-in-one that even kept the DVD drive. However, when it booted it would not display at the required 1680x1050 resolution of the cinema display.

I had thought that the ECX board simply could not output at the requited resolution.  The ECX board has a PCI express x 4 slot, I attempted to add  a PCI express x1 Ion graphics card, while this fixed the resolution problem, the ECX ples the graphics card no longer easily fit into the iMac G4's chassis.

I was wrong.  The ECX board can support the resolution, it seems to have a quirk with the cinema displaythat it detects it as multiple monitors one of which is a lower resolution.  When I manually adjusted the resolution in windows and turned off the "phantom display", the display became full size.

Although I have not minded having the external mini, this board gives essentially the same power as the newest mac mini plus it has 4GB of ram and uses compact flash for a SSD, if its "hackintoshable" - I do not know yet.

I still did not want to alter my old mod in any way that may damage it, nor did I want repeat the same cinema display hack.  I wanted to use the existing iMac G4's monitor housing.  This brings me to the second thing I had overlooked.

I decided to use the Apple Cinema Display enclosure because the iMac G4's monitor enclosure fits the lcd panel and its specially made super thin inverter and NOTHING else.  And I was never able to figure out how to use the native G4 inverter without the G4 motherboard itself.   For the first time I decided to compare the apple cinema display's inverter to the iMac G4's to see if there was any way the cinema display's inverter could fit within the G4's monitor housing.  Thats when I noticed the 8pin connectors were almost identical.

The iMac G4 only uses 7 of the 8pins, however when the one was not connected, it would not turn off immediately when the computer slept, so I will have to make sure I have one extra wire going through the neck to use all 8 pins of the inverter.  To my surprise when all 8 pins were connected it worked perfectly.  If there was any difference I was unable to see it.

Being able to use the native inverter meant that I could use the native iMac G4's monitor housing with the Apple Cinema Diaplay if I could find a place for one more board - the LCD controller board.  The controller board is very flat but is not flat enough to fit withing the housing.

Comparison of iMac G4 bottom with native motherboard vs. ACD LCD controller

Unlike the inverter whose high voltage cables should not be extended through the neck, there is no reason why the lcd controller can't be placed in the base and its cables extended to both the inverter and LCD panel.

As it is just as plat as the native motherboard which I will not be using it can fit at the very bottom of the dome.

The only true nuisance with this is that although both panels use TMDS signaling, the neck needs to be modified.  The existing Inverter wires can stay, but by placing the controller in the base, there are a total of 27 wires that need to extend up to the neck.  The black and grey wires combined have 22 wires.  Plus I needed one extra wire for the 8th inverter wire, making a total of 28 wires.  To add additional wires, I did take apart the neck and change the microphone, lcd wire to an additional grey iMac TMDS cable that I had from a different neck.  Once I had all the connectors soldered on I was able to put the inverter and lcd on one side of the neck and the lcd controller and ecx board on the other.

Unfortunately it does not look like I'll have room for both a power source and a DVD/Bluray.  I will be able to fit one or the other.  Right now I'm leaning towards keeping the drive and having a power brick external.  I want this mod to look as genuine as possible, as such I'm forgoing anytouchscreen option.

Powering it on revealed a clear image:

Now to internalize it into an iMac G4 20" shell to see if it will fit.  This is the most hopeful I've been for a genuine iMac G4 20" all-in-one with modernized hardware.

As always, feel free to ask any questions.

Step by Step Apple Cinema Display LCD Housing / 20" iMac G4 Touchscreen Mod

This guide details how to attach the cinema displays LCD hosing to the top of the neck without the forward displacement caused by using a VESA mount.  This technique can be used with other monitors.  Since the base components depend on what you intend to use this for, I have not gone into any details on the base here.


iMac G4 20" / Apple Cinema Display Parts List:
iMac G4 20" (Can be broken)
Apple cinema display 20" with PSU
5 wire resistive touchscreen
5 pin male to female touchscreen extension cable

Tools:
Rotary dremel with many cut off blades and sanders
Tin snips
Needle nose pliers
Mini screwdriver set
Allen wrench for cinema display stand
Full set torx screwdrivers or attachments
Soldering iron with solder
Wire cutter and stripper
Pliers
Duct tape
Gorilla glue
Cold weld
Multimeter with continuity check
Several sheets of grey styrene

I. Opening the Apple Cinema Display (This site is an Excellent Resource)
- remove stand by first unscrewing Allen bolt on each side then the 3 small torx-6 screws on underside of stand.  Pull to remove
- insert a small flat screwdriver and pry off the white side panels on both sides
- disconnect the power/brightness panel
- unscrew all the mini screws
- use a mini screw driver to lift off side metal panels
- unscrew top large screw on both sides
- use flat mini screw driver to pull on sliding tabs on both sides at the bottom of the monitor.  Pull tabs out - monitor should open
- disconnect 2 pin front led indicator
- slide monitor out feeding the cable through the hole in back until entire monitor is free.

Courtesy of The Ignition Project

II. Disconnect the cable.  The white cable splits off into several connectors that plug into the monitors boards.
- disconnect the black power connector by pressing down the latch
- disconnect the 5 pin cable from control board with needle nose pliers
- unplug the mini USB and FireWire cables that come from rear cable
- disconnect the 30 pin JAE connector that plugs into LCD by pressing in on clip on both sides simultaneously
- remove cable that attaches JAE connector and connects immediately to control board using needle nose pliers

III. Free the cable
-  using wire clippers or scissors all outer shielding (tan plastic) must be removed from cable.  remove all string.
- the big plastic block can be removed by slowly cutting with wire clippers or dremeling with cut off blade VERY carefully
-  in the end you should wind up with 4 independent cables surrounded by silver mesh ending in 4 white plugs
       a) The 30 pin JAE plug (with it's attachment) joins up with the 5pin connector to form 1 cable ending with DVI connector
       b) The power cable (black latch at one end, other end plugs into PSU)
       c) FireWire cable
       d) USB cable

IV. Opening the iMac monitor
- unscrew 3 torx-6 screws at bottom of monitor housing (be careful not to strip the screws)
- slide out front which should contain the LCD itself
- disconnect the wires including front led (try not to damage for later use), microphone, inverter cable, and 30 pin JAE connector to LCD
- use torx screwdriver to remove four screws holding bezel onto neck
- remove wireguard
- slide wires through hole and place monitor housing to the side

V. Open base
- almost all torx except for bottom plate - phillips.  will not get into, can remove everything (would leave drive tray)
- at top unscrew and free neck from base (save all screws)

VI. Wiring the neck
-  There are two options here I detail the differences in this post.  I'll discuss the one I went with the "hybrid method"

- Open the neck using taped together miniscrewdrivers
-  Find the microphone/led cable.  It is labelled.  The lcd side breaks into two parts.  One with 2 wires (LED), one with three(microphone)
-  This wire is tapped to another inside of the neck.  Gently cut the tape holding the wires together.

-  Cut this wire in half inside the neck and remove the cut wire from both ends of the neck.  (There is no use for these very small wires and this cable is the same size as the larger gauge power cable wires which will be taking its place). 
- Cut the connector off the black power cable.
-  Place the 3 wires (without the connector) into the neck start at the bottom hole and then through the top hole.
-  Pull through so that there is at least 18" of wire on the lcd side of the neck.
Close and seal the neck in the same fashion it was opened
-  Remove the native iMac's 30 pin JAE connector by cutting the wires.  (The pins in the connector are too fragile and not worth saving).
- Remove the pins gently from the iMac's inverter connector.
-  It should now look like:

-  Take the USB, DVI, and 5pin connector cable fome the apple cinema diaplay and cut off at least 12" from the LCD side.
-  You will now need to solder the power connector back on from where it was cut.
-  Solder the iMac G4's black wire (the one that has 3 wires that split into green, red, and shield) onto the ends of the Apple Cinema Displays JAE connector wires.  Use the soldering iron itself to melt the plastic covering as these wires are otherwise impossible to strip.
-  Solder 5 wires from the iMac G4's Gray cable onto the ends of the Apple Cinema Display's 5 pin connector.
[Although it probably doesn't matter which color wire you choose as long of you solder the bottom end onto the same wire, I used the wires that served the same function in the native iMac.]
-  Solder the USB onto 4 remaining wires from the gray cable
-  Solder 5 wires from the inverter cable to the male end of the 5 wire touch screen extension cable.
-  Repeat this process for the bottom half.  Making sure to solder the same wire to the bottom half that you chose for the top. REMEMBER TO PUT THE DVI CABLE THROUGH THE HOLE IN THE BASE BEFORE YOU SOLDER.
- Wiring the neck is detailed in greater depth in this post


VII. Making the Monitor casing
-  Unscrew the metal bracket that pokes out of the back of the Apple Cinema Display's Case

-  Using a flat screw driver pry up the metal plate that is glued down to the back of the Apple Cinema Display's housing.
-  Remove the inverter from the iMac G4's monitor housing
-  The inverter is held on by several screws
-  Using needle nose pliers pull out the 4 bolts in the iMacs back case that the inverter screw into
-  Place the Apple Cinema Display inside of the iMac G4's housing.  With the bol's removed it should fit flush and snug
-  Turn it over - The back of the apple cinema display should be visible in the iMac G4s hole where the neck used to be
-  Using a pencil trace that hole.

- Using a flat head screwdriver you will need to separate the iMac G4's metal housing from the white plastic it is glued to.  (To do this you will likely snap the white plastic several times).

-  Using tinsnips and a rotary or multimax dremel cut out a bracket from the center of the metal casing that includes the circular neck attachment.  Be patient, this is difficult to cut and will take some time.

Comparison of original and new bracket

If you are planning on incorporating a touch screen, trimming weight will be important.  Consider further cutting this bracket down to a smaller size.

Further Cut-down bracket

-  Using tinsnips cut out the hole that was traced on the back of the apple cinema display
-  Place the neck through the hole to ensure that it will fit
-  If small modification is needed use the dremel with either a cutting or sanding part.

With hole cut

-  It should now look like this
-  Position the bracket inside the apple cinema display and use the screws to secure the new monitor housing in place.
-  Make sure that the monitor is not rotated.

-  Trace around the bracket to record the proper position
-  Remove the monitor and bracket from the neck
-  Using grey styrene cut out small fill-ins for the two lines that come off the new hole as well of a circular fill in to the Apple cinema display's original hole
-  Glue these in place
-  Now position the bracket in place and Cold Weld vs Gorilla Glue the new bracket firmly down to the inside back of the apple cinema display's housing


VIII. Further Modification for use with touchscreen (This is only for people who wish to add the same touchscreen I did).
-  Cut further weight from the bracket as documented above
-  Trace the touchscreen dimensions on the front of the Apple Cinema Display's Bezel
-  Dremel out the inner portion of the front bezel
-  Fuse the LED cables from the two different monitors
-  This step is documented in great detail in this post.


VIII. Putting in the LCD
-  Place the cables through the bottom opening of the Apple Cinema Display
-  Reconnect to the LCD
-  Lift the LCD screen into the bezel.  As you do this try to keep the wires from stacking on top of each other (This can be a pain) otherwise it will not close easily.  (If you are using the touchscreen, try to leave that connector/cable accessible towards the bottom of the screen)
-  If you are using the touchscreen - place it in the modified front bezel and wrap the ribbon cable inside the bezel around the LCD and connect it to the 5 pin connector.
-  Leave the on/off brightness cable sticking out the side
-  Connect the LED cable (if you are using the modified original iMacs, wrap the ribbon cable around the bottom of the LCD.
-  Push in the pins at the bottom to close the display.  You should not have to use any force.  If you do readjust the wires behind the LCD.

20" iMac G4 TMDS-DVI Pinout - UPDATE: CONFIRMED

Update 11/2/2011: I have finally solved the native inverter issue and as a result, used the same method I used for my 17" Mod and can now say that this pinout works.  A guide will be coming in he future as well.

I have received a request for the TMDS-DVI pinout of the 20" iMac G4.  Just like the other iMac G4 panels there is a TI chip which converts TMDS to LVDS, so with a DVI cable and power source the native lcd should be usable with any DVI compliant source.  However, the caveat here is that I have been unable to get the native inverter to work properly.  So, while there may be an image, with no backlighting - it will be very difficult to see.

That said there are work arounds:
1) Aftermarket inverters (works great, needs only 12V, 5V and ground), but I have not found one thin enough to close the case completely - but if you don't mind a little buldge, this does work fine.
2) Alternate Backlighting (LED etc)
3) Get the native inverter working:
       What I've learned: It requires a 24V and 3.3V line.  The Dimmer seems to work backwards of most where it requires 3.3V for maximum brightness.  There is certainly a way to do this, but I have already damaged several in my attempts and I felt that even if I got it working, finding adequate power sources that would work together would be difficult.  You would have to use a powersource that has a 24V line such as the native power source for the 20" or the iMac G5's.  I didn't want to have to "turn on the backlights" with a separate switch.  The Apple Cinema Display also uses a 24V line, so I initially thought about using its power brick.  Thats when I realized that the power wiring including a brightness switch and on/off were already done for me by using the 20" apple cinema display itself.  Conveniently, its the same size including thickness and weight as the iMac G4 20"s monitor and housing.  This led me to my Apple Cinema Display/iMac Mod, which has exceeded expectations so far.  But, I can understand the desire to get this as "genuine" as possible.

iMac G4 20" TMDS-DVI Conversion

So here is the TMDS/DVI conversion chart.  This is based on the LCD panel: Id Tech 20" LCD.  Notice there are significant differences from the 17".  This includes different placement of the shield wires and some grounds as well as higher voltage requirements.  Because I never got the inverter working, I have not verified this, nor do I plan to.  As long as ID tech did not misprint the specs, there is really no way this could be incorrect, but you never know until you try. Update: Never say Never

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.

17" TMDS-DVI Neck Variation

There are indeed two different types of 17" iMac G4 necks and the wire color does vary between them.

1) Part # 661-2716.  This neck comes from the 800mhz 17" iMac

2) Part # 661-2825.  This neck comes from the 1Ghz and 1.25Ghz 17" iMac

I believe that thee are the only two variations that exist, as I have not been able to find any different part numbers for iMac 17" necks, though I can not be certain.

I am fairly certain that my neck came from a 1.25Ghz machine, so those modifying a 1 or 1.25Ghz iMac should be able to use the pinout I have posted.  However, those modifying an 800mhz will have different colored wires.

As of right now, I would still recommend opening up the monitor and looking at the JAE connector and following PIN NUMBER instead of WIRE COLOR.  As the LCD panels are the same the pin number will always be correct.

I am trying to obtain a completely intact version of each of these necks to detail the differences and will post the differences when I do.  Several people have gotten this working, while others seem to be having some trouble.  I will try to go through this step by step and post detailed instructions of how t connect this.  I will also try to do it using a spliced DVI cable as most people seem to be going this route.

I am also working on the step by step for the cinema display 20" mod for those interested in doing that