Monday, May 25, 2015

Modding your iMac G4 into a Modern Computer

iMac G4 from Power PC to Modern Intel Desktop

Dremeljunkie and the iMac G4

I started this blog to share some projects, the most important of which became the conversion of the iMac G4 to something that could be used with a modern day processor.  The PowerPC processor went from being slow to obsolete to essentially unusable, which relegated the most elegant desktop computer I've ever used to little more then a showpiece.  As I progressed, I wrote this blog as an experience journal.  I tried several different approaches (probably around 20) and had some success with 9 different methods, these are detailed in my Summary of iMac Mods post.  But, many of these are clearly inferior and more difficult then others.  Some are even potentially dangerous and I've kept those posts up only for historical purposes.  Several posts are even dead ends that were not viable at all.  As a result, this blog can be quite difficult to navigate for those trying to perform this mod.  To help with this, I am writing this post to point those looking to do this in the right direction.  I am thrilled to see that many people remain interested in this computer and this mod and I hope this post will help make the information contained in this blog easier to follow.

The iMac G4

The iMac G4 has one feature that makes it extremely difficult to mod, the neck.  As this is the feature that gives it its defining characteristic, it can not be eliminated or bypassed.  The neck is difficult to open and barely has enough room for the remarkably thin wires that Apple has already passed through it.  The G4 was designed as an all-in-one in two compartments and works unlike any other computer before or since.  Some components usually found outside the LCD are actually inside of it and certain components usually found paired with LCD screens are pulled out and found in the base (the power supply or Motherboard itself).  This made getting a video signal from a different CPU and motherboard through the neck and to the existing monitor difficult.

My goal was always to find a reproducible way to make the screen compatible with a standard video input signal which terminates in the base.  Though, an all-in-one was not overly important to me (I currently use it daily as an external monitor with a Mac Mini) I did go on pair it with several small form factor boards as an all-in-one, the best of which was a Intel NUC.

Next are the hyperlinks to the posts that I believe represent the best ways to do this mod for the different models and sizes.

The Mod

A) The Mods Over The Years:


A Summary and the PROS/CONS of all the G4 mods that I have performed over the years. Although most of these I no longer would recommend, they may still prove valuable to someone and the above hyperlink is where you will find them.

These range from an all-in-one with Intel NUC in the base to a black paintjob on the base and an alternate black monitor attached to the neck to incorporation of parts from an Apple Cinema Display.

B) The 15" iMac G4


The most important information needed to perform this mod is the pinout of LCD wires originating from the neck.  Because the iMac G4 uses TMDS signaling it contains the basic components needed to carry a DVI or HDMI signal to the LCD.  This uses the native wires and thus opening the neck is not necessary.

Personally, I found the 15" screen to be uncomfortably small and have never modded one.  The pinout available in this post was provided by modder pgee70.  Thus, only the pinout is seen in this post, but the principals are no different from the 17" mod, only the order and color of the wires vary. Use the 17" mod tutorial as a guide, but follow the pinout seen here instead.

C) The 17" iMac G4

The 17" iMac G4 is easier to mod then the 20" because you do not have to deal with the complexity of the inverters 24V power requirements.  The tutorials provided for the 17" are the most detailed and include video guides.  The principle behind all these mods are very similar and I think the 17" Tutorial is a worthwhile review for anyone attempting any iMac G4 Mod.  As I was focused on making a 20" for myself, the 17" mod is taken to the the level of getting a DVI cable into the base. If you wish to incorporate an Intel NUC in the base, please see the 20" guide as placing an NUC in the base is essentially the same no matter what the size of the screen.

The 17" had processors of 3 different speeds.  What took me a while to figure out was that there are 2 different wire layouts/necks.

The 800mhz varies from the 1 and 1.25Ghz Model.  To figure out which you have please read this post: The Two 17" Necks


The DVI Connector that makes this all possible
iMac G4 17" 800mhz TMDS Pinout
If there is one piece of advise I can give, it would be this: BUY THIS DVI CONNECTOR, the MOLEX PN 74320-4004.  I can not put into words how much easier it makes doing this mod.  It can be found easily and is available from $2-$5 for several of them.  For more details click this hyperlink to my post about it: The Easiest Method.

HERE IS THE HYPERLINK TO THE TUTORIAL ITSELF INCLUDED IN THIS POST ARE EMBEDDED LINKS TO THE VIDEO TUTORIALS.  THIS INCLUDES THE 17" STEP BY STEP GUIDES FOR BOTH 17" NECKS: iMAC G4 17" TMDS to DVI GUIDE

Look Here for the Video Tutorial Only

As this tutorial does not really "use" the base, but only uses the LCD and the neck, the power source I used comes from an AC to molex adapter (12VDC, 5VDC).  There is really no reason not to use the existing iMac power supply as it provides 12V and with a downconverter or (if making an all-in-one) a USB port of your new computer motherboard/NUC, its easy to get a 5V line. The 5V line in the native iMac comes from downconversion on the motherboard itself and is needed to turn on the LCD. For information on using the native power supply use this hyperlink: iMac G4 17" Power Supply.

D) The 20"iMac G4

iMac G4/iMac G5 External Monitors with Mac Mini
This is far and away the machine I have spent the most time modding and would recommend (due to the largest sized monitor).  I currently have two setups that I use using two slightly different methods, both of which work quite well.  The first is an an external monitor with a iMac G5 modded with an Apple Cinema Display with working iSight Camera and mic (click the hyperlink for information on the iMac G5 mod if you're interested).  This mod like the G5 relies on components from a 20" Apple Cinema Display and contains the cinema display powerbrick and a DVD drive (functions as an external drive) in the base of the iMac G4.

The second is an All-In-One Hackintosh 10.9 using only the existing iMac parts itself.  This is by far the easier of the two and leaves the entire base available to place a small motherboard/NUC.  This is also the basis of my tutorial.

To better understand these mods, a little backstory.  The difficulty of the mod was figuring out the inverter which required 24V in order to work.  There is only one neck and the LCD pinout is essentially identical to that of the 1/1.25GHz 17" iMac G4, but I could not get the inverter working, nor could I replace it as it is paper thin and no other inverter would fit in the LCD housing (not even the inverter on the Apple Cinema Display.  The 20" Apple Cinema Display, The iMac G5, and the iMac G4 use essentially the same TMDS panel (The iMac G4 is made by ID Tech, The others by LG) and are pretty much interchangeable (Though some slight physical modifications to the housing sometimes have to be made for it to fit perfectly).  While putting the Apple Cinema Display in the iMac G5 housing, I realized the extent of this compatibility and came up with the idea for the first version of the iMac G4 20" Mod.

1) The iMac G4 20"/Apple Cinema Display Mod

Initially, I had this mod setup as an all-in-one, but then converted to an external monitor with an "external" DVD drive in the base.  I did this because I prefer the mac mini to a hackintosh, but its a personal preference.  This mod uses the iMac G4 housing, inverter, and neck, the LCD screen from either the G4 or the ACD, and the controller board, power supply from the ACD.  Because there are more wires needed for the ACD, the neck does have to be opened and one wire swapped out for a different wire.  The additional wire I used was the LCD signal wires from a different iMac 17" 1/1.25Ghz neck.  So obviously, this mod requires a lot more "stuff".  It is possible, because the controller board of the ADC works with the iMac G4s inverter.  However, there are 8 wires to the ADC inverter and only 7 to the iMac G4 inverter.  Luckily, there is a space for an 8th wire on the G4s inverter and it seems to serve the same function.  Thus, an extra inverter wire is needed (using one of the extra wires in the neck) for it to function properly.  Here are the hyperlinks to the relevant posts.  Again, remember, it was written as a journal and I unfortunately do not have a full step by step tutorial, but can give additional information to anyone who requests it.

The hyperlinks/relevant posts:

This is obviously a more complicated and potentially expensive mod then using only the iMac G4 20".  There are some advantages, however, to doing it this way.  As you are using the Apple Cinema Displays controller, it is really an Apple Cinema Display and is recognized as such.  With a controller board, you can adjust the image including resolution, brightness, etc.  You can not do this when hooking directly into the LCD without a controller.  It is also potentially more stable.  The controller board also has 2 USBs and 2 FireWire ports which can be utilized and since the controller is extended to the base of the iMac G4, it is easy to do so.

2) The iMac G4 20" All-In-One-Mod

Although there are some advantages with the first mod, they aren't big enough that I would recommend doing that mod over this one.  This one is much easier and uses only the components of an iMac G4 20" itself, making it much less expensive and wasteful as well.

This uses the same LCD pinout and the native inverter, but uses either a 24V upconverter or the native power supply (recommended) in order to supply the necessary voltage to the inverter.  In the Step by Step I give instructions on either using the native power supply or upconversion method.

Initially, I used a KEEX-6100 ECX board as the motherboard, but then upgraded to the much better Intel NUC Ivy Bridge motherboard, which is vastly superior, as the KEEX was not really intended to be a consumer motherboard.

Hyperlinks/Relevant Posts:





There are other interesting posts about other smallform factors as well as some info about hackintoshes in general. These posts can all be found within this blog. But, these are the most relevant to those who wish to perform this mod itself.


E) Other Information

The question I most often get is if a new version mac mini will fit and the answer is - no.  The posts block it, so the options are currently, an all-in-one hackintosh or an external monitor.  Personally, as the mac mini does not take up much desk space, and that I do not find hackintoshes to be overly reliable, I would recommend this approach.  Hopefully, apple will one day, reduce the mac mini's footprint, but to date this has not occurred.

The Harmon Kardon Globe Speakers are classic and to some (myself included), important parts of the iMac G4's appearance.  For information on using these speakers and the ridiculous lengths Apple went to to make these speakers as incompatible as possible.  See this post: The Apple Pro Speakers.

For some general advise about modding the iMac G4, this is probably worth a read: iMac G4 Mod Advise.

I hope this helps simplify this site for those attempting to mod their iMac G4s.  It is truly a beautiful machine.  I am holding off on further mods until more then incremental gains are seen.  Redoing the computer for Ivy Bridge to Haswell for instance is not really worth it.  A smaller form factor mac mini is really what I am waiting for.  Thank you for reading and good luck.





34 comments:

  1. I can't thank you enough for all the valuable information. I'm starting my first 20" NUC mod at the moment and wouldn't have been able to start it without your blog!

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  2. Yes, thank you for such an informative update.

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  3. Hello! All here is amazing, and I'm happy to re-confirm the 20 inches IMAC g4 with native PSU works for me!
    I needed 1- about a week to read most of this website, 2-look closer to pictures, 3.then re-read and...finally -I got my 20'' working as external monitor! Thanks! This time the mod is done in Sofia, Bulgaria.
    Kind regards!

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    Replies
    1. Delighted to hear! I actually love hearing that people are having success. Without being able to convert these, they would all eventually find themselves in the dumpster. This way, I feel they can at least be recycled and be useful once again. Glad to help!!

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  4. Hi Dremeljunkie,

    have been reading your blog for years but only recently got imac lucky. i have two 17" to experiment with, and would like to know if you have any current recommendations for any currently available touchscreens.

    thanks for your hard work and great documentation!

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    Replies
    1. Sorry about the late reply. The best is probably a capacitive touch screen from 3M. It does add weight as it is glass, but it's much better then the plastic resistive overlays that negatively affect the LCD image quality

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  5. Very Good. While recent designs are similar, the 2014 generation witnessed new breakthroughs. 27inch screen with Retina technology 5K, for 5120 x 2880 resolution pixels, up 67% compared with the 4K pixel is one of the bright points of time changes.!

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  6. Hey I'm interested in using an iMac G4 (i think 20") as an external monitor with my 2014 Retina MacBook Pro. I love the look of the old iMac and being able to swivel and rotate it will be nice as I do a lot of app development and video editing. Do you have any recommendations? Also how hard would it be to put in a 1080p or 4K display in there?

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    Replies
    1. It would be cool to use the disc drive as a DVD or Blu Ray writer, but I understand if this is impossible or very difficult.

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    2. having a few functional usb and maybe even firewire or audio ports would also be great. Help would be very much appreciated on this project.

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    3. Although I've made NUC hackintoshes the mod I actively use is an external monitor for a Mac mini. Unfortunately, for the 20" a resolution upgrade is not possible without a major change to the LCD housing. The reason is that the 20.1" 16:10 LCD has been dead for years. In fact, the G5 and Apple Cinema Display Monitors were pretty much the last of them. You would need to construct an entirely new LCD enclosure for a different screen format.

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    4. Using the drive as a bluray writer or DVD player is quite easy. The drive is easily swappable and an SATA to USB converter can be used to turn an internal drive to an external USB drive. Similarly, a usb hub could be added to the base to give you extra ports

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  7. I know you said that a mac mini will not fit inside the base. Judging by the date of this post I assume this is a post 2010 mini? How close did it come to fitting? I am just wondering if one of the pre-2010 models will fit inside the base. I know this is aging hardware as well, but it is over an inch shorter in width and depth and it will run the latest versions of OSX. Is this something that you have tried? I would totally be willing to sacrifice a bit of compute power to get an intel mac fully enclosed in the g4 base :)

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  8. I am a noob so please bear with me. I have two concerns, I do have an old imac cube and could use the 15" g4 as a display and housing for an external drive or can I install a Raspberry pi unit and use it for that purpose.
    How difficult is each one? I read through your 17' modification but got a bit lost. Cool project nevertheless.

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  9. I am a noob so please bear with me. I have two concerns, I do have an old imac cube and could use the 15" g4 as a display and housing for an external drive or can I install a Raspberry pi unit and use it for that purpose.
    How difficult is each one? I read through your 17' modification but got a bit lost. Cool project nevertheless.

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  10. I like my old mac mini, especially as a back up computer for basic operations. Plus I like the old version of Itunes, before it got so complicated.

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  11. I have imac 24.5 inches which is still working well but im thinking to use the LCD as stand alone monitor for my PC. Can its works?

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  12. Hi thank you for all the information you've provided. I'm starting a project and my plan was to purchase the imac 21.5 4k retina lcd panel and atempt to make a monitor. However i don't know what to purchase to get it to run with the little information i have.
    The plan was to purchase
    21.5 4k retina lcd panel
    Lcd Driver
    and the psu
    now do i'm not sure what i need from there besides connectin the lcd driver to the power board and the power board to the lcd. now i was wondering if i would be able ton purchase a lcd controller board or possibly make one that will allow me the still use the 4k resolution
    i still want to use the mini display port to connect to te screen so theres no need to change the interface to dvi
    I was wondering if i could get some imput on this.
    Thank you
    Any language is welcome I can translate it

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  13. Hi DremelJunkie

    I'm about to start a project to put an RPi 3 in a non working 20" iMac G4. But before I start, do you have any suggestions on how to test the display to determine if it is good before investing a lot of time and money into the project?

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