20" iMac G4 Intel NUC Ivy Bridge AiO Mod (Videos)

A video demonstration of my updated iMac G4 mod/hack (NUC/Ivy Bridge Mountain Lion Hackintosh)

 

Part 1:

Introduction and General Overview (YouTube Link)

Part 2:

Turning It On and Testing It Out (YouTube Link)

So that pretty much completes this mod.  I have thought about new HD 21.5" LCDs to the top of the arm in a custom LCD case that mimics the iMac G4, but I am not sure that would add very much.  This monitor falls just short of HD and I have not had any issues with it in terms of quality.  Though its something to consider for the future.  I find that larger monitors start to look "awkward" with the base.  Although placing the Cinema Display on the top of the monitor worked.  It wasn't until I went back to the original that I realized it was "off".  It didn't droop or tilt, but it didn't move as smoothly as the original.  The neck was obviously designed very specifically for the native monitor.  This includes not only the weight, but the thickness and shape as weight distribution changes as you tilt and swivel the neck.  Unfortunately, without the R&D budget of apple, its hard to design a new neck, but the old one works beautifully with the native LCD.

I would still like to make this into a touchscreen and perhaps add an iSight.  The awkward size and Mac compatibility issue make this difficult.  While I have a capacitive screen that works, its thick and heavy and would require dramatic hardware changes (LED lighting with custom thin diffuser) or physical changes (altering the LCD case and front bezel).  I am still hopeful that touch films will eventually be readily available, adding touch capability of any size with negligible cha ges in thickness.

Anyway, I'll worry about that later and enjoy this computer for a while.  I have tons of pics from this and previous mods, as well as the ability to fill in gaps with surplus materials.  As such, I'm thinking about putting together a "Moving Picture" Video Guide.  Sort of a compromise between a written and video guide.  I'll be able to explain from start to finish, step by step, how to do this with audio and annotated pics.  Let me know if this sounds at all interesting or useful to anyway.  Thanks for reading/watching.

iMac G4 Ivy Bridge Hackintosh: Finishing Touches

Completed Mod

While the previous Sandy Bridge Mod worked fine, this board is simply a perfect fit.  It runs cooler, uses less power, keeps the optical drive, supports mountain lion, uses the native PSU (which not only ditches the external power brick, but it even provides 30 extra watts of power).  This is much more stable.  Only S3 sleep (S1 works fine) remains a problem.

A Great Fit

The two extra additions are the 12V to 19V upconverter, which powers the actual motherboard.

and the Wide Input PSU, which allows the peripherals (The optical drive and the Fan) to turn on only when the motherboard is on and activates the PSUs 24V line via its 5V switch.  Both these fit (although its tight) and work perfectly.

With the exception of some cosmetics, I have completed the back ports.  They include 4 USBs, though 1 is used by a small Bluetooth adapter, a 3.5mm audio jack, the native AC power plug, and a "fake" Firewire 400 plug.  Its fake because it isn't a true firewire cable, it is only connected to a 12V Molex/Ground, so it supplies only power.  This is for use with the Griffin ifire adapter which gets its power from firwire and its signal from a 3.5mm audio jack and has an apple minijack out for the apple pro speakers.  This is very much akin to the original apple pro speakers that came with the G4 Cube.  They used an external amp which plugged into a special "high voltage USB port".  So although the speakers are not directly plugged in like the original, with the iFire, no additional power source is needed.  I did not want to break open and try to internalize the iFire.  This would have wasted the valuable iFire and constrained this mod to only those speakers.  The iFire also allows lengthening of the speaker cable, which is far to short on the apple pro speakers.

Other small improvements include:
Using KeyMap4Macbook to allow the keyboard button to eject the SATA to USB drive.

Changing the Mac Mini Pic in Resources to the 20" iMac G4, so the iMac's pic displays in "About this Mac".

About this Mac

The Full View

I will do a video shortly and am hoping to combine old pictures and new pictures into a comprehensive guide for doing this, including parts list.

Almost all the shortcomings of my previous mod has been addressed.  I am really pleased with this and hope this is helpful to others interested in this mod.  Thanks for reading!

A Great Little Board

A Change of Heart

When I first ordered the Intel NUC, my purpose was to see if this form factor had promise for the future.  I also figured that this small board would be useful to test projects and perhaps even wind up as a little media center somewhere.  In truth, I did not expect to seriously consider this board for the iMac G4 project. After working with this board for a while, I have to admit, its pretty fantastic.  For one, the size is remarkable, especially when it is removed from the case. This makes even ECX boards look big.  Secondly, its dead simple, it uses EFI bios, requires only RAM, a half height WiFi mSATA, and a full size mSATA SSD.  The mSATA in particular makes the system even smaller.  There is no need for even a 2.5" drive and nearly all wires are eliminated in this fashion.

 

As opposed to the other boards, this board only contains a Core i3 processor and there is a paucity of USB ports (only 3), mSATAs (one half height, one full height), an HDMI connector, and either a Ethernet + extra HDMI or Thunderbolt. (Depending on which of the 2 models you choose).



A Look Inside

 Despite these negatives there are other advantages this board has.  The availability of 2 RAM slots for a max of 16GB.  Thunderbolt while (at this point) is expensive and has few compatible devices does leave open impressive possibilities including hubs, a second display, and even a pci express graphics card.  The size also leaves most of the base available as it fits between the native PSU right under the fan and allows you to keep the optical drive (though a USB connection would be needed as there are no regular SATA hookups).

The Software/A Mountain Lion Hackintosh

The only method I use is tonymac's retail Mountain Lion Unibeast/Multibeast install method.  While the other boards took a very long time to get right, this could not have been easier.  I did know in advance to change the graphics to 128MB and of course AHCI instead of IDE (for the SATA controller).  Except for these small changes, there is almost no way to go wrong.  I used the Easy Beast Install with the Mac Mini 6,1 definition.  Now the reason for this is that there isn't much to the board, while other motherboards are loaded with other chipsets for gigabit Ethernet, SATA controllers, Touchscreen controllers, other I/O controllers, and business related QM chipset features, this board is really only about the basics.  But, with hackintoshes, less is more.  Having to clear your CMOS after you mistakenly enable some feature is no fun.  Neither is having to reinstall the OS because you decide to try to get native audio to work one last try.  This makes it very time consuming when it comes time to upgrade your OS.

 

One note,  I have read HDMI audio does require a work around, but this obviously does not apply to this mod.  Without any other audio cable out, a USB audio card will be needed.  But, so far airplay seems to work flawlessly, and can make for a wireless alternative.  So, in short, if a modestly powerful Ivy Bridge Hackintosh is your goal for this mod, I would recommend these boards above the others.  Being the easiest to find and the most affordable also doesn't hurt.

 

About This Mac

 Some Technical Issues to Solve:

1) Ports: 3 USBs is simply not enough and for basic function more is needed.  Thunderbolt hubs are absurdly overpriced right now, but either a Thunderbolt to SATA and/or USB or a regular USB Hub will be needed.  One USB is needed for the 5V "backlight power on" signal.

2) Fan:  there is a directional fan, but due to the faraday cage, I would still like to add the case fan in some manner.  This may involve replacing the existing fan and situating it directly underneath the iMac's case fan, splicing the fan wire to power it.  Or, running both, using the PSU to drive the fan (though a manual control knob may then make sense).

3) Power switch: This is hard soldered to the board.  A bypass will need to be wired up and I am fairly sure this can be done in an easy to reverse way.

4) Audio: A USB audio solution is needed.  This is not a difficult thing to find, but I am considering an airplay or Bluetooth based solution.

5) Bluetooth: I have been unable to find a Wifi/Bluetooth combo half height card that will work so far, so I will have to go with a Bluetooth dongle.

6) The Optical Drive: Using this solution means using USB to SATA to connect to a drive, but it will still need to be powered.  May require 12V to 5V downconverter.

7) Power: Worst case Scenario would involve connecting AC to the small power brick that comes with the NUC, but this seems like a waste.  Unfortunately as this board needs 19V, either an upconverter or downconverter will be needed to go from either 12V or 24V.

Concluding Thoughts

Although I'm not certain, I am actually leaning towards this board,  If this was an i5, putting it on par with my previous system (with more RAM and better graphics) this would be a slamdunk.  Each EPIC or ECX board requires different connectors, drivers etc. As Intel is likely to continually upgrade this form factor, getting this right may "future proof" future designs.  I am likely to build this out and see what the final project looks like and how it functions.

 

I will certainly post detailed instructions and may do a video guide if there is enough interest.  Thanks again for reading!

 



SUCCESS - TWO OUT OF THREE (RUNNING OSX 10.8) AINT' BAD

The hardware part of this mod has already been completed, for the most part.  The next step is software and finding a build that will run Mountain Lion without much compromise, is the goal.  Out of the 4 boards I am working with, I have had tremendous success with one, partial success with another, hit a dead end with a 3rd, and the 4th is somewhat of a backburner side project (upgrading my previous sandy bridge mod to core i7 Quad and Mountain Lion).

 

Lets start with Success: THE EPI-QM77

THE BUILD

This is the EPIC board, it is slightly larger than the ECX board, but fits easily within the dome.  As always this is a purchased retail copy of Mountain Lion using the brilliant tonymac's Unibeast/Multibeast install method (Thank you again tonymac).  Changing the SATA from IDE to AHCI was the only change I had to make in the bios, otherwise it installed natively.  Interestingly, I had trouble getting the USB to function from a USB 3.0 port, but when I plugged it into the apple keyboard's USB via the USB 3.0 it worked fine.

An Ivy Bridge "MacBook Pro" in an iMac G4 shell

I am still tweaking the multibeast settings somewhat, but will report them with final recommendations shortly.  As you can see, this build eschews the optical drive for the native PSU.  Although this is cleaner as there is no power brick, I have mixed feelings about loosing the aesthetics of the drive.  Its getting harder to justify what is really a cosmetic feature at this point.  I am still trying to devise a use for this and to somehow incorporate a usb powered motor to open and close the door revealing a hot plug or extra ports.

I will have to see what might be needed from a cooling perspective, but I may need to upgrade to a larger heatsink, but can not be sure until the computer is fully assembled.

This is likely the build I will keep as this board has everything I need, Core i7 Quad Ivy Bridge with HD4000 graphics, Enough USB 3.0 slots and 2 SATA 6.0 ports.  Even a quality 7.1 Realtek Audio Chip is included.

 

The "Looks Promising" Board: THE INTEL DC3217BY

Rear ports

On tonymac's forums I have seen successful hackintosh builds using the sister model which has ethernet and two monitor support.  This is the "higher end" model because of the inclusion of a thunderbolt port.  With the help of mikeboss' tip to set the graphics to 128mb, this board was able to post.  I did not go further as a mSATA is required and I did not have one large enough until now.  I have installed this Crucial 128GB mSATA, as well as a broadcom half height wifi card.  As this board is nearly identical, I suspect I will have similar success.  The question will be the thunderbolt, which I am hopeful will work natively.

With RAM, Wifi, and mSATA installed

I doubt this board will end up in this build permanently, but its an important proof of concept.  I believe that this tiny form factor has potential and Intel is currently pushing it for hobbyists.  Hopefully they will continue to improve and expand this line.  However, this first generation is underpowered with a core i3 vs the other boards.  Also it has few ports.  While the thunderbolt is intriguing and the idea of having all the ports in the back connect to one thunderbolt internally (ethernet, extra display, usb's etc) similar to apple's cinema display, thunderbolt accessories are currently way overpriced.  This board, as its the most compact, is the most versatile and is likely to have many uses in other projects.  That said, nothing is certain, and I will see this through.

 

NOT AT ALL: The Gene HM-76

I had high hopes for this ECX board, but I am currently having issues with the DVI display.  I am unsure if this is a failure of the board or its ability to communicate with my DVI/TMDS mod.  There are a few things I still want to try. 

 

WAITING IN THE WINGS: THE KEEX-6100

As Lion ran so well on it, I doubt Mountain Lion will be a problem, but I will test this as well as the core i7 processor.

OTHER OPTIONS:

A New QM-77 Ivy Bridge Board:

Quanmax will be releasing the Ivy Bridge KEEX-7100 and 7101 which contain embedded Core i5 and Core i7 mobile processors respectively.  ALthough I have a fondness for Quanmax and its KEEX boards have served me well, this board is not yet available and this is somewhat late in the game.  As I frequently change processors and tinker, I try to avoid embedded systems if possible (no other option with Intel NUC, but price is actually reasonable for a processor included system), but it remains a viable alternative.  

The Old Mac Mini:

I have been looking at ebay and the white polycarbonate Core 2 Duo systems are falling in price.  While the new boards are too big, the older style will work, but price to performance has been a limitation.  Although underpowered, there is a huge advantage in a native OS X machine and the final iterations (2.5+ Ghz) are still capable machines.  I will have to see if I can obtain one at a reasonable price.

Thanks for reading, will keep updating as I go.

Ivy Bridge Upgrades via Small Form Factor Boards

The Current SFF (Small Form Factor) Market and Trends:

As I mentioned in a previous post, I had suspended work on my iMac G4 20" upgrade until Small Form Factor Ivy Bridge Boards become available.  I have become somewhat of a small form factor enthusiast as a result of these projects and am excited by the accessibility of what previously were industrial only form factors as well as new specifically targeted enthusiast boards such as the Raspberry Pi, Android Compatible ARM boards, and Intel's NUC line.  I am pleased to report that I am in possession of one SFF Ivy Bridge Board and have another two ordered and en route.

As the size and power consumption of powerful processors and boards continue to decrease these mods will only continue to get easier, more diverse, more powerful, and less expensive.  The one "nuisance" of the recent computing era (at least for these projects) has been an unbalanced focus on shrinking things primarily by thickness.  The ultrabook and tablet markets have caused a "flattening" of components without as significant a change in the other dimensions.  Take the Mac Mini for example, the overall volume decreased as a result of a dramatic reduction in height, but this was in spite of an actual increase in the footprint (length x width).

Old on top, New on bottom
Courtesy of CNET

SFF Computing and iMac G4 Mods

A Tight Squeeze

As far as the iMac G4 mod (and many other mods/projects) are concerned this can actually complicate things.  For those not familiar with my approach to the iMac G4 is Mobos smaller = better.

To sum up, the original iMac was convection cooled were physical contact via heat pipes carried heat to the top of the dome where a fan blew out. Thus the very poorly ventilated case was designed to be cooled with room temperature air coming in through slits at the bottom of the dome and hot air being blown out through the top of the dome.  Any air cooled motherboard/cpu (by far the hottest and most important component) benefits from being as close to the top as possible because it decreases the distance the heated air has to travel before it reaches the case fan and ventilation and decreases the heat of the overall dome and the heat the components above the mono/cpu are subjected to.  Also, probably most important, placement at the bottom of the dome will unavoidably result in poor, obstructed ventilation.  Any other component, especially wiring, will have to go above the CPU and mobo.  As the dome tapers to the fan at its apex and the faraday (metal inside) cage makes most of the periphery of the dome difficult to use for components.  If all you want is a motherboard and cpu, it can be done with a large heatsink to the top of the dome and a low thermal output processor, but no other components could be added and wiring would still be difficult.

Using a small form factor board allowed me to use a Core i processor at the top of the dome and allowed the rest of the dome to be used for a pico PSU, a full 5.25" optical drive, and a 2.5" solid state HDD.  As the widest point base still barely fits a mini itx (and port blocking is a problem), so options have been limited.  I am fairly certain the the mac mini will eventually shrink in all directions and that it will be suitable for a G4 mod.  In addition, I am hopeful, new form factors of computing will emerge and we will see other alternatives to the ultrathin rectangles that dominate today.  But for now, this is what I am working with:

Current Ivy Bridge SFF Options:

I will be reviewing each of the options based on features, cost to performance ratio, size and workability with the iMac G4 mod, and "hackintoshability".  Therefore, expect this post to be a work in progress with periodic updates.  Again, I am focusing on high performance x86 architecture, but this is by no means a slight to alternatives such as low-power Nano/Pico x86 boards or increasingly popular ARM devices, this is simply a matter of personal preference.

Choice 0: Quanmaxx KEEX-6100 ECX board

KEEX-6100 with large heatsink

I am listing this as "Choice 0" because it is based on Sandy Bridge Architecture, but it has been overwhelming successful particularly as a hackintosh running OSX Lion.  It is available from Quanmaxx's USA store and is even available in a wide temperature variant.  Here it is seen with an extra large heatsink I adapted when I upgraded this to a Core-i7 Quad.

Choice 1: Avalue's EPI-QM-77

Front View

Though this EPIC board is slightly larger, this board is"thinner" as a result of more room for ports on the edges, thus no need for the stacked ports seen on the ECX boards.  It remains a small form factor that easily fits the iMac G4 chassis.  It is available from Global American and I have it in my possession and just started working with it.

Back View

In terms of size, here are pictures of this board in the middle with a Core i Mini-itx on its left and the Quanmaxx (with regular heatsink) on the right.  The first picture shows overall dimensions,while the second shows thickness/height.

From Left to Right: Mini itx, EPIC, ECX

From Left to Right: Mini itx, EPIC, ECX

Choice 2: Aaeon's GENE-HM76 ECX

Also available as a more expensive QM77 (has extra corporate features, most apple mobile Ivy bridge processors are HM77 (very similar to HM76).

Courtesy of Aaeon

This is a true ECX board and identical in size to the Quanmaxx ECX.  I have purchased this board from NextWarehouse and it is en route.

Choice 3: Intel NUC: DC321BY QS77

Courtesy of Newegg

Although it only contains a Core i3, this is the one I am most excited about.  This is because of reasons outlined in my previous post.  This is the smallest Core i board that intel believes is possible.  This board is targeted at the mainstream and this model includes thunderbolt connectivity.  This comes with a "chassis" and is likely to see upgraded models at regular intervals in the future.  It is widely available from vendors including Newegg.  It has been ordered and I will continue to update as I learn more.

The 17" iMac G4 Native PSU

Introduction

While I have not hooked the native PSU up to a mod and there is one wire that I do not understand the purpose of, I have checked all the collages of a working PSU.  I now know that is it similar in principal to the 20" PSU.  As this is all based off of my work with the 20", more information is available in that post:

The 20" iMac G4 Native PSU

17" iMac G4 PSU

vs ATX PSU

ATXPSU

The Native PSU is an always on, 12V only power supply.  Always on meaning that unlike standard ATX PSUs, the moment the AC cable is plugged into an outlet, there is DC power in the pins.  To get an ATX PSU to work without a motherboard, a pin in the motherboard connector needs to be grounded (known as "jumping" the PSU).

12V only means that unlike standard PSUs, only 12VDC and Grounds are supplied to the motherboard.   ATX PSUs transform the 120VAC in the wall to 12V DC and also downconvert the 12V to 5V and 3.3V.  These 3 different DC voltages are supplied to the motherboard in multiple rails via a 20 or 24pin connector.  Because the PSU supplies the iMac's motherboard with only 12V rails, the downconversion to 5V and 3.3V happen on the motherboard itself.

ATX PSUs also tend to supply peripherals directly, Molex, SATA power, 8pin PCIe etc emanate directly from the PSU itself.  As noted, ATX PSUs are not "always on", they have to be "jumped" either manually or by the motherboard.  As a result, the peripherals will not be given power until the motherboard is switched on, despite the fact that the power is supplied directly from the PSU to the peripherals.  Because the iMac's PSU only has 12V, the one molex line with 2 molex connectors (for the cd and hdd) emerge from the motherboard.  Although the molex wires share the same 16pin connector, it comes from the motherboard and does not interact with the PSU at all.  As the peripherals are supplied by the motherboard they will be off when the mobo is off despite the "always on" PSU.

The Connector

"Clip Side"

"Non-Clip" Side - All Grounds

The connector is 8x2 for a total of 16pins, one slot is empty for a total of 15 wires.  Of those 15, 4 (Yellow, Red, Black x 2) go from the main connector to the molex connectors.  Because we will not use of the original mobo, these wires connect to nothing and have nothing to do with the PSU at all.  That leaves 11 Power supply wires.  The blue wire seems to have no detectable voltage and grounding it does not seem to have any effect.  In the 20", the blue wire acted as the ground component (with a white wire supplying +5V DC to the PSU - the white wire is not found on the 17" - the pin is left empty) of a switch to turn on 24V DC supply to the LCDs backlight.

In the 17" the 24V Green line is replaced by an extra yellow +12V DC.  While I do believe this (similar to the 24V required by the 20" backlights) does go to the blue wire of the inverter to supply the power to the backlights, the "switch" to turn the backlights on works differently.  Here the extra 12V DC line is on as soon as you plug in the power cable.  This is the same as the other 12V lines.  No voltage needs to be applied to the PSU in order to get all the lines working.

So, I am not exactly sure the purpose of the blue wire.  Since, I don't have a working 17" mobo to even voltage test it.  I do have a theory, I believe it acts as a ground for a similar switch mechanism as seen in the 20", however, this switch (which also uses 5V) happens in the inverter itself, not the PSU.  I'll talk more abut this later.  For our purposes its really of no consequence.  What we are left with is 10 PSU cables, 5 Yellows and 5 Blacks.  This means there are 5 12V DC rails supplied to the motherboard, as soon as the iMac is plugged in.

The Pinout:

17" iMac G4 PSU Pinout

Please note this is an alteration of an image from my 20" pinout - hence the crude "photoshop"

Again I break it down into four zones:

1. Yellow Zone: Pins 1 - 4 and 9 - 12: 4 rails of 12V DC and grounds

2, Blue Zone - Pin 13 - The blue wire is the only pin (will not be used here)

3. Red Zone - Pins 6, 7, 14, and 15 - The molex connector comes out from here.  You will want to save the actual wires and connectors for use in this mod, but these pins are of no consequence.

4. Green Zone - Pin 8 and 16 - This likely is the 12V rail which the motherboard routes to the inverter, but since its automatically on and we aren't using the original mobo , its just another 12V DC rail with ground to us.

Getting a 5V Line:

The 2 plug connector connects to the AC port on the back of the iMac G4 which contains the C5 receptacle (The 3 pronged plug with 3 circles that resembles Mickey Mouse).  This plugs into the AC on the wall and there is +12V DC in our yellow wires.  In total there are 5 rails (Pairs of Yellows and Black Ground wires).  However, this mod calls for a molex adapter to be used as a PSU.  The molex adapter has a Yellow +12V DC rail and a Red +5V DC rail.

My switch theory (Optional Reading):

The 17" Inverter Pinout

For those of you that are familiar with the 20" PSU you may be aware that I mentioned in my post that a 5V line is not necessary to get the LCD working.  This is because the one place on the 20" that required 5V was "the switch".  This switch worked by the motherboard downconverting 12V to 5V then feeding it back to the PSU via the White/Blue wires.  The 5V turned on an upconverter (or possibly a transformer) that produced the 24V line.  +24V now flowed in the Green wire of the PSU, this went through the connector and got directly routed through the motherboard to the Blue/Red (+24V)  and Green/Black (as Ground) wires of the inverter cable.  When 24V reached the inverter the backlights turned on. On the 20", I used the 5V that came from the DVI cable.  As this is just a switch I was not worried about overtaxing the low current available in this line.  

For the 17" PSU, there is no switch involving the PSU.  The Yellow wire at the end (in the Green Wire's Place from the 20") is on as soon as it is plugged in.  However, I believe there is a similar switch mechanism, but it is in the inverter, not the PSU.  The 20" has 6 backlights, the 17" has 2 backlights, so I understand the need for (2) 24V lines and (2) Grounds.  In the 17" inverter cable there is (1) Ground and (1) Power Wire +12V via the Blue Wire.  Initially I thought that 5V was also somehow required to power the inverter, however after some experimentation, I realized the 5V required for the Red inverter cable acts as a switch and not as a true "power source".  Because of this, the Red Inverter cable can be connected to the DVI +5VDC power source.  Obviously this is similar to what I just described as the switch mechanism in the 20" iMac G4.

The 20" Inverter Pinout - Revised

Comparing the 2 inverter pinouts shows similarities.  The Orange (Dimmer) and Purple (Possible role in Sleep?) are left unconnected.  The 6 backlights in the 20" need two power rails, so both Blue and Red wires supply + current with Green and Black as their respective Grounds.  The 17" has 2 backlights and needs only one power rail, the Blue wire as + current with Black as its Ground.

In addition there is a Yellow in the 20" and a Green in the 17" that need very low current via Resistor connected to 5V.  This wire appears to be involved in wake from sleep.

All wires are accounted to except for the RED wire in the 17" inverter cable.  This wire uses 5V produced by the motherboard from downconversion of the PSU's 12V and uses it to "turn on" the inverter, acting as a switch.  This is exactly what the White Wire (which is missing from the 17" PSU) of the PSU does for the 20". Except it acts at a different location.  This also makes me think the remaining Blue Wire may somehow be a ground wire that the motherboard uses for this mechanism.  But, as we ground our 5V DVI Current via the DVI, it is not used.

Need for 5V and Preparing the PSU:

Although the inverter could probably all be handled by the DVI input (could likely get away connecting the Green inverter wire as well.  There is one more thing which requires 5V, the LCD itself.  The Gray cable of the LCD contains 3 wires which power the LCD screen.  In the 20", 12V is needed, but in the 17" 5V or 3.3V is needed.  As this is not just a switch, but actually powering something, I would not use the DVI source as you will likely overtax it.  This may actually damage your source, computer, video card etc.  So 5V must be created from the PSU.

At this point, I would recommend cutting off the motherboard connector to free all the PSU's wires.   Right above where the wires enter the connector cut them free.  This gets rid of the molex connector (you do not need the cut these 4 as they are not attached to the PSU itself).  You should be left with 5 Yellows, 5 Blacks, and 1 Blue (which will not be used) coming out of the PSU.

Option 1 - A computer in the base:

This is for how that are using some type of small form factor board i.e. Nano, Pico, or ECX.  Many of these boards are powered by a P4 connector.  This is a 4 pinned connector (2x2) that uses 2 - 12V and 2 - Grounds.  As there are plenty of 12V rails available from the PSU, simply take your motherboard power connector and attach the 12V DC lines to the Yellow wires from the PSU and the Grounds to the Black PSU wires.  In the picture of my KEEX-6100 below, the P4 connector can be seen in the front right corner of the motherboard.  This connector attaches to a 12V rail from the native PSU.

KEEX 6100 with P4 connector to Native PSU

The reason this will work is that this board (as well as several other small form factor boards) works just like the original iMac G4 motherboard in that it requires only 12V in to work and it itself has downconverters on it.  The KEEX-6100 actually has a mini-Molex/SATA power out port, which can be seen in the back, just left of the fan.  This gives a couple molex out, including 5V.  So you have a 5V line from here.  Just note that I would still recommend taking the 12V backlight power from a Yellow 12V rail from the PSU itself, but the LCD power and ground can connect to the Red 5V and Black-Ground line here.  The Green from the inverter can also go here or the DVI 5V as noted.

Option 2 - Use a second PSU - a PICO PSU connected to the native PSU

A PICO PSU with rocker switch

Almost all PICO PSUs use 12V DC input (some have wide ranges in DC input).  Power it by hooking a 12V line from the native PSU to the DC power in (the white and black wires pictured that hook up to the connector for an external power brick).  As the native PSU gives you 12V DC already, you do not need a power brick.  You must "jump" the PICO PSU in some fashion, depending on what your intended iMac G4 mod is.  The Jump mechanism can be "always on" with a simple wire or "on/off" with a rocker switch (as pictured) to control power out from the PSU.

If you are using a motherboard in the base that requires an ATX Power connector, this is without a doubt the way to go.  You can plug this into the motherboard connector, without having to wire all sorts of adapters and converters, at a negligible loss of space.  Of course if its connected to an ATX mobo, the motherboard will jump it for you.  

If you are using this for an external monitor with peripherals (ex. dvd drive), you can use the requirement to "jump" this psu to your advantage.  You can put a rocker switch here that will allow you to turn off everything its connected to.  Remember the native PSU will be on as soon as you plug it in, by jumping this psu without a switch, it will also be on.  Thus, drives will be spinning, leds will be glowing etc whenever it is plugged in.  With a switch here you can turn the whole unit LCD and peripherals completely off.  Just remember, no matter what wattage PSU you get, these are not additive, they are connected in serial, so you are still limited by the overall wattage of the native PSU.  Also, you have to make sure that the wattage is adequate for anything you have connected "downstream" of PICO PSU including the LCD power (though the backlights can be connected to either the native or PICO PSU).

The PICO PSU is probably the most flexible option as they are available with P4 connectors. molex connectors. SATA power connectors etc.  If you are not using an ATX motherboard, you could even use the power from the pins intended for the motherboard.  However its expensive and not needed if you use Option #1.  And if you aren't using peripherals requiring 5V - you can likely use the cheaper option #3.

Option 3 - Use a 12V to 5V DC-DC Downconverter

15W 12V to 5V DC downconverter

These can usually be found for around $5.  Connect one 12V and Ground in and you get 1 5V and Ground out.  Combine this 5V rail with a different 12V from the native PSU.  With a 12V and 5V rail, we now have our "molex wires" that acts as our power source.

All these are acceptable, as is using a different PSU altogether, it simply depends on your goals and needs.  As always - thanks for reading!!

20" iMac G4 - The Native PSU

20" iMac G4 LCD powered only by Native PSU

The Native PSU is not enclosed.  Once it is plugged in, it is live.  Please use extreme caution with both the Power Source itself and its wires.  Keep any conductive objects away from the PSU and do not handle either the PSU itself or make changes to its wires while it is plugged in.  As always, proceed at your own risk.

Background

C5 receptacle
Courtesy of Wikipedia

From the onset of my 20" All-In-One Sandy Bridge mod, it was clear that the native PSU was not going to fit (from both a physical space perspective and a heat generating perspective).  It was either the optical drive or the native PSU.  I kept the optical drive and used a PICO PSU instead.  This put most of the physical bulk and heat generation on the outside of the mod in the form of a power brick.  However, I certainly understand the draw of using the native PSU. First, a modder likely alread has one, its right there in the iMac, no extra parts need to be purchased (the cost can be substantial as high wattage Pico PSUs cost around $150).  Secondly, there is no power brick, the rear plug would house a receptacle for the rounded, 3 pronged C5 plug of the native iMac G4.  Third, and most importantly is that it was designed to power this display.  Because of this it has a wattage greater than any PICO PSU (190 watts) and has a 24V line for the display, eliminating the need an up converter or separate 24V source.

20" iMac G4 Native PSU

Connected to AC C5 Recepticle

The problem, or so I thought, with the Native PSU has been that it can not be "jumped" in a conventional manner.  "Jumping" is a technique used in conventional ATX PSUs.  Grounding (connecting to a ground wire) a particular pin in the motherboard connector causes the PSU to "turn on" in the absence of a motherboard and the momentary switch that the mobo provides to turn the psu and subsequently the computer and internal devices on.  A few intrepid readers have let me know that they have had success "jumping" by supplying 5V to a particular pin in the motherboard connector.  I had thought of this PSU as a variation of an ATX PSU, with similar properties.  The problem I had envisioned using this solution is I figured a separate 5V source, in the form of a second PSU would be needed to give 5V to the native PSU in order to "turn on or jump" the native PSU.  While this may have allowed for a low wattage second PSU, because you still needed a different PSU, it somewhat defeats the purpose of using the native PSU.  I was mistaken, at least for the 20" PSU.  This is not how the native 20" PSU works at all.  I did initially have a working PSU for the 20" (Side note: The PSU seems to have the highest failure rate of any iMac G4 20" part and has been almost universally dead on every non-operational 20" iMac G4 I have obtained), so I purchased a known operational PSU.  The one I bought is green and like everything with these computers, I have seen variation in the PSUs even between the same size iMac.  So, I can not say for sure that all PSUs will work like this one.

How Does It Work

"Clip" Side

The PSU doesn't really need to be jumped at all.  It is "always on".  Looking at the motherboard connector, one side (that has the motherboard clip on it) has 4 yellow wires, then a blue, then yellow and red that go to the molex, and finally a green wire.  The other side (without the clip) has all Black Wires except for one White Wire.

"Non-Clip" Side

To be honest, this PSU confused the hell out of me and I believed I had a defective PSU initially.  It was the Molex connector here that really threw me off.  To test PSUs, I have a Molex powered fan that also lights up.  I attach this to a molex connector from the PSU.  When I turn on a PSU, I expect to hear the fan and see the LEDs turn on.  This fan (like most) uses 5V, so it really only connects to the 5V lead (Red Molex) and a ground.  No matter what I did, I could not get the fan to turn on.  Of course, I could have supplied the 5V directly to the pin the fan was connected to, but that seemed ridiculous.  In truth, 5V being supplied to this pin is likely what happens with the native PSU/Mobo setup.  It wasn't until I tested the voltage on one of the (non-Molex) Yellow wires that I realized that the PSU was in fact live as soon as it was plugged in and the Yellow lines have +12V DC on them.  This PSU appears to be a variation of a "12V only" PSU (with one notable exception).  12V only PSUs rely on the motherboard for the DC-DC downconversion and most modern ones have 5V and 3.3V rails.  12V only PSUs are usually PSUs for low power boards.  It appears that the PSU supplies the motherboard with 4 12V rails in the form of the 4 yellow(12V) and black(ground) wire pairs.  This is similar to using a PCI-E 8 pin power connector (or 2 P4 power connectors).  The molex power actually emerges FROM the motherboard, 12V directed from the PSU through the motherboard out to the yellow molex and the 5V a result of the motherboard down converting 12V to 5V and sending that through the Red 5V wire.  So when I hooked the fan up to the molex, without a motherboard, I was in essence hooking it up to nothing.  It is pretty obvious that the molex wires come from the connector and not the PSU at all.  Initially however, I thought these wires might interact with adjacent wires within the connector itself, but this is not the case.  That leaves the green/black and white/blue wire pairs.

Looking at the motherboard side

The Green Wire (only on the 20") likely represents the only DC-DC conversion that the PSU does itself.  And its an up conversion from 12V to 24V (Though this could also be generated by a separate transformation from the AC current).  The Black wire that it is paired with is simply a ground wire.  There is no voltage detected when you plug the PSUs AC Cable in.  This is because the motherboard "tells" the PSU to supply the 24V rail only when its on.  The motherboard does this by supplying a +5V current to the White Wire with the Blue Wire acting as the ground in this circuit.

The PSU Pinout:

ATX PSU Pinouts

Naming Convention of ATX PSUs numbers from Right to Left, Top then Bottom, looking at the open pins (motherboard side) of the connector while the clip is positioned on the bottom.  I will keep this same convention for the pin numbers I use for the iMac G4s native PSU.

20" iMac G4 PSU Pinout

The pin numbers are identified on each pin.  I have also divided the 16 pin connector into 4 colored zones.


Yellow Zone (Pins 1-4 & 9 - 12): These 4 yellows and 4 black wires are on as soon as you plug in the PSU.  Each of the 4 Yellows (9 - 12) has +12V DC and the Blacks (1 - 4) are their corresponding grounds.

Blue Zone (Pins 5 & 13): These 2 wires form a powered switch.  By supplying 5V+ to the White Wire (Pin #5) and grounding the Blue Wire (Pin #13) the PSU turns on Pin #16, the Green Wire.

Red Zone (Pins 6,7,14,15): These 4 wires were used by the iMac G4 to power the optical and hard drives via 2 molex connectors.  The 12V for the Yellow and the 5V for the Red and 2 Black Grounds came from the motherboard.  As these are simply a molex cable hooked up to nothing, you can ignore these wires.

Green Zone (Pins 8 & 16): +24V will be supplied by the PSU via the Green Wire (Pin  #16), which is required for the backlights, when 2 conditions are met: The PSU is plugged in and the White/Blue (Blue Zone) Wires are supplying 5V, turning the the "Switch" on.  Pin #8 is the Black Wire Ground for the backlights.

Applying this to the 20" iMac G4 Mod

This will only make sense if you are familiar with my more recent TMDS to DVI iMac G4 mods.  In this case knowledge of the 20" iMac G4 mod in particular is recommended.  Click the link below for details:

All in One 20" iMac G4 Sandy Bridge Mod

and the iMac G4 20" Inverter Pinout:

Updated iMac G4 20" Inverter Pinout

I used a PICO PSU for this mod.  The PICO PSU has 12V rails, 5V rails, and 3.3V rails (the 3.3V rail is not needed for this mod).  In addition, I used a 12V to 24V DC-DC Upconverter to get the 24V rail required for the monitor.  To replace the PICO PSU with the Native PSU you need the PSU to supply 5V, 12V, and 24V.  As the native PSU has 12V working as soon as you plug it in, we have our 12V rail.  As noted above, if you supply 5V to the Native PSU, a 24V rail will be turned on, so 24V is taken care of.  This leaves only the need for a 5V rail.  While 5V is not actually needed by either the LCD or the backlights itself, you would need 5V for any device that is molex or SATA powered.  This includes hard drives, fans, optical drives, and even touch screens.

There are 4 basic ways to get 5V, which one you choose depends largely on what you intend to use in the base.

1) Use a second PSU - a PICO PSU connected to the native PSU

A PICO PSU with rocker switch

Almost all PICO PSUs use 12V DC input (some have wide ranges in DC input).  Power it by hooking a 12V line from the native PSU to the DC power in (the white and black wires pictured that hook up to the connector for an external power brick).  As the native PSU gives you 12V DC already, you do not need a power brick.  You must "jump" the PICO PSU in some fashion, depending on what your intended iMac G4 mod is.  The Jump mechanism can be "always on" with a simple wire or "on/off" with a rocker switch (as pictured) to control power out from the PSU.

If you are using a motherboard in the base that requires an ATX Power connector, this is without a doubt the way to go.  You can plug this into the motherboard connector, without having to wire all sorts of adapters and converters, at a negligible loss of space.  Of course if its connected to an ATX mobo, the motherboard will jump it for you.  

If you are using this for an external monitor with peripherals (ex. dvd drive), you can use the requirement to "jump" this psu to your advantage.  You can put a rocker switch here that will allow you to turn off everything its connected to.  Remember the native PSU will be on as soon as you plug it in, by jumping this psu without a switch, it will also be on.  Thus, drives will be spinning, leds will be glowing etc whenever it is plugged in.  With a switch here you can turn the whole unit LCD and peripherals completely off.  Just remember, no matter what wattage PSU you get, these are not additive, they are connected in serial, so you are still limited by the overall wattage of the native PSU.  Also, you have to make sure that the wattage is adequate for anything you have connected "downstream" of PICO PSU.

The PICO PSU is probably the most flexible option as they are available with P4 connectors. molex connectors. SATA power connectors etc.  If you are not using an ATX motherboard, you could even use the power from the pins intended for the motherboard.  However its expensive and not needed if you use Option #2.  And if you aren't using peripherals requiring 5V - it is way overkill and you should use Option #4.   I'd even recommend hooking up the White PSU wire using #4 and using the 5V rail from the PICO PSU only for peripherals because #4 works the best for sleep/wake.

2) Use a small form factor mobo that uses 12V only for power (ex KEEX ECX boards)

Many small form factor boards including ECX boards use a P4 connector.  This is a 4 pinned connector (2x2) that uses 2 - 12V and 2 - Grounds.  As there are plenty of 12V rails available from the PSU, simply take your motherboard power connector and attach the 12V DC lines to the Yellow wires from the PSU and the Grounds to the Black PSU wires.  In the picture of my KEEX-6100 below, the P4 connector can be seen in the front right corner of the motherboard.  This connector attaches to a 12V rail from the native PSU.

The KEEX-6100

The reason this will work is that this board (as well as several other small form factor boards) works just like the original iMac G4 motherboard in that it requires only 12V in to work and it itself has downconverters on it.  The KEEX-6100 actually has a mini-Molex/SATA power out port, which can be seen in the back, just left of the fan.  This gives a couple molex out, including 5V.  So you have a 5V line from here.  However, as above, I'd still recommend hooking up the White PSU wire using #4 and using the 5V rail here for other peripherals as #4 works the best for sleep/wake.

3) Also a 12V to 5V downconverter can be used:

The PSU circuit

AC Plug into the wall is transformed into 12V DC by the PSU and plugged into the motherboard supplying 4 12V rails to the mobo.  When the power/momentary switch is pressed the motherboard turns itself on, opens gates to downconvert some 12V current to 5V.  Power is sent from from the motherboard to the 12V and 5V rails of the molex wire to supply the drives.  Also 5V is sent in a circuit back to the PSU via the white wire and back via the blue wire.  This turns on a transformer or up converter on the PSU which then sends 24V via the Green wire to the LCD.

This is actually quite brilliant and remarkably simple.  This opens up several intriguing possibilities for future mods.  My first test was to add 5V via white/blue from an AC to molex and confirm 24V on green/black with multimeter.  I did not want to add a second PSU and I knew power was technically already flowing to the 12V rails, I simply mimicked the motherboard using a very small, inexpensive 12V to 5V downconverter.

15W Downconverter

The PSU circuit and how I created it:

I cut free from the motherboard connector these wires: (The grounds are interchangeable, I used the matched pair across for convenience)

12 to 5V DC-DC downconverter hooked up

1 Yellow/Black (NON-MOLEX)
The White/Blue
The Green/Black

The Yellow was connected to 2 wires:
   The alligator wire the comes from the 12V LCD wires in the Gray Cable of the neck (Purple, Yellow, and Orange).  I also connected this to the 12V input of the Downconverter.
The Black was connected to the Gray Cable of the neck/LCDs grounds (Blue, Green, Gray, and Pin 15 of the DVI).  I also connected this to the ground input of the Downconverter

The White was connected to the +5V out of the downconverter and the Blue connected to the ground out of the downconverter.

The Green was connected to the inverter cables Red/Blue (+24V) and the Black to the inverter cables Green/Black (Ground).  Turn in on and there is the video.

Native PSU and LCD reunited

4) The Best and Easiest Way using the DVI 5V Pin

Overview

Really the best and the easiest way to do this especially, if you don't need a 5V rail for anything except for the LCD monitor is to use the 5V from the VEDID.  The is pin #14 on the DVI Connector itself.  5V is sent from this via the DVI source (ex the computer) to Pin #14.  This pin is intended to carry the 5V to the LCD panel via the Hot Pink/Red wire in the iMac's Gray LCD cable.  We are already splicing this 3 times so far.  One goes via the Hot Pink/Red Wire to the LCD as noted.  One goes to a 1Kohm Resistor to DVI Pin #16 (The Hot Plug Detect).  The third goes to a 6.8Kohm resistor then to the Yellow (?Wake from sleep wire) of the inverter cable.  By splicing this again we get 5V which can be sent via the White wire of the native PSU to turn the 24V line of the LCD on.  You can splice this anywhere along the line, I did it at the cable that comes to the Yellow wire of the inverter.  I connected an alligator wire to the White Wire of the PSU and hooked it up to the line going to the connection between that line and the 6.8Kohm resistor on the side before it passes through the resistor.  This seems to work beautifully and results in the screen going completely dark during sleep appropriately.  To be honest, I'm kind of blown away at how elegantly this works.

Now if you see 5V for anything else, you will need one of the above methods.  Meaning, use this for the LCD, but if you want to power a drive in the base DO NOT USE THIS SOURCE YOU WILL DAMAGE IT! You will need some type of downconverter, either a standalone or part of a motherboard as mentioned above.

This has gotten me to rethink LED backlighting and I may try adding the touchscreen in some fashion using the existing CCFL LCD.

It is amazing how the components of this decade old, little machine continue to amaze me.  Whether its the mechanical grace of the neck, the remarkable use of convection cooling, or now even a simple/elegant power supply solution for such a limited space, the iMac G4 is truly an inspired design.  To those working on the 17", I have posted information on that inverter which works in a similar fashion.

Thanks for reading!!!