GUIDES and TUTORIALS

Sorry about the delay but...

After completing my latest mod, I promised a guide.  Due to personal reasons, I have not had a chance to work on this.  As time goes by and it is less fresh in my mind, it becomes somewhat more difficult to compile.  While all the information to do this mod is within this blog, it is not very well organized.  The Monitor to DVI instructions are contained within the 20" Sandy Bridge Guide.  While I talk about the native power source in this tutorial, I use a PICO power supply in this actual mod.  The native PSU is really discussed in a different post.  Likewise, wiring up the new NUC board is in a different post altogether.

I had initially constructed this site to be a "Tech Journal/Diary" where the most recent updates would be chronologically first and older entries could contain outdated or incorrect information.  As I became more involved in the iMac G4 project, this site became more of a guide/tutorial site.  While this isn't a bad thing, its just not exactly how it was designed to be.

As I've been putting together the tutorial for the 20" Ivy Bridge NUC Mod (in the form of audio over pictures), I've realized that this may be the opportunity for a "redesign".  I would like to keep this site as my tech journal site.  Even the failed mods and the process behind them is something I would like to "preserve".  I have secured "imacmods.com" and I am hoping to eventually link between these two sites for a more cohesive and straight forward experience.  Someone wanting to know how to connect the native PSU can click on it and either go to a written tutorial, video guide, or original dremel junkie post.

It is certainly not lost on me how confusing it is to google "iMac G4 Update" and think you've found the answer only to find several posts detailing somewhat related (but not the same mod).  Also, from my end, I have step by step photographed, documented, and wired up two different 17" necks (one on video) and a 20", and am now going to repeat it again for the 20".  This will allow me to have a "modular" approach where 'for instance' STEP B: Conversion to DVI remains the same regardless of which computer you use in the base.

I would greatly appreciate any advice from those more skilled than me at web site creation.  I would like it to be simple and easy to follow, but am a novice at this.  Please let me know if you have any suggestions.

The 20" NUC Tutorial

I want to assure you that this will not interfere with the 20" NUC tutorial.  The biggest hold up has been the fact that I am not 100% happy with the amount of pictures and detail that I captured.  My goal was to complete the mod and I was not as thorough with photographing and documenting the steps along the way.  Although I do not have a problem opening up my mod.  There is no doubt that I will have to do a decent amount of disassembly to get the pictures I would like.  If I am going to disassemble my mod, I would love to upgrade it in the process if possible.  Luckily, it does appear upgrades are not far off courtesy of Intel and Gigabyte:

From Gigabyte - The Brix:

Courtesy of Computerbase.de

Courtesy of Computerbase.de

This NUC based system is smaller, lighter, has more I/O options and will have i5 and i7 options.  While initially Ivy Bridge based, Haswell is likely not far behind.

And Intel:

Rend Lake will be i5 and USB 3.0 capable based of Ivy Bridge Architecture.

In retrospect the use of Thunderbolt was a waste on the initial NUC.  Initially I thought it would be "future proofing", but its been months later and the only intriguing peripheral is Belkin's (finally being released) $300 Thunderbolt dock.  Of course, its the USB 3.0 that makes this dock interesting.

Thus, this NUC should be far more versatile (at least I hope).

I am unsure of the variation in the "Horse Canyon" Core i5, it doesn't appear to use a Haswell Chip, though I can not be sure.

"Skull Canyon" is the Core i7 Variant, and the one for which I am most excited.

Of course, updates are always going to happen, and while these are only incremental upgrades, I have been looking for an opportunity to add USB 3.0 in particular (and get rid of the thunderbolt).  As these seem like they are "around the corner", I am asking for patience in terms of the guide.  Replacing the board is not difficult, but it would make more sense to only disassemble and reassemble this mod once.

So please stay tuned and hopefully the tutorial will be done shortly, with an even more powerful NUC serving as the computer.

EDID and HDCP

Some of you may have noticed an"incompatibility" with certain sources.  Sometimes this is due to playing digital protected content "HDCP" or even using certain motherboards.  For myself, the EPI-QS77 and I am told the Raspberry Pi as well, seem to cause incompatibility issues.  In some cases, changing from DVI to HDMI and back can remedy the problem, other times, artifacts persist in the monitor.  My guess is that some boards may have an incompatibility with the "EDID", the identifier of this LCD.  While there is no direct way around this, there is an "indirect way".

The White Polycarbonite Family

As I have mentioned before, prior to figuring out direct wiring of the existing LCD, I had found a work around.  This "work around" is used in the iMac G4 (pictured above) and although its just serving as a monitor (with a modded iMac G5), I have now been using it daily for over 2 years without any problems whatsoever.  This work around keeps the native inverter and can keep the LCD or use an LCD from an aluminum Apple Cinema Display or iMac G5.  The most important thing is that this uses the controller board from an apple cinema display.  While this does involve opening and rewiring the neck, it does give the LCD a true EDID and HDCP compatibility.  There are certain other advantages as well, but it is more technically challenging and will require some parts from a cinema display.

I mention this only to gauge interest.  Are there people who have experienced this problem? Are people interested in this particular method?

Thank you all again for your patience and thank you for taking the time to read this.

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 "Next Unit of Computing" - A Small Form Factor for Mainstream Users?

Courtesy of PC World

Pictured above is an all in one kit which contains a new Intel sponsored form factor called the NUC or "Next Unit of Computing" which if rumors are to be believed will go on sale this fall.  This little box features an Ivy Bridge Core i3 Processor, including HD 4000 graphics.

At 4" x 4" (102 x 102mm), the motherboard contained within is even slightly smaller than the smaller side of ECX boards (105 x 146mm - yes the 3.5" board is not actually 3.5", but it is the same size as 3.5" drives, which are not 3.5" but have 3.5" platters inside them).  These boards are smaller than the semi-mainstream nano itx boards (120 x 120mm) and even give the ultra-tiny PicoITX (100 x 72mm) a run for its money.

The only information I know comes from these articles:

Engadget's Story on the NUC

PC World's Story on the NUC

The Top of the NUC
(Courtesy of PC World)

But, if this is to believed, this would be a huge boon for hobbyists, modders, and small form factor enthusiasts.  To summarize, Intel undertook a project to determine the smallest possible form factor that would be needed to support a full Ivy Bridge CPU + Expansion and came up with NUC.  I had actually  read about this in an article several months back, but moved on when I read that intel sees this being used in digital signage and kiosks.  I thought that this was just a slightly different form factor for industrial/embedded applications that I've talked about many times on this blog (ECX, EPIC, etc).  I do not know if this was intel's goal from the beginning or if the popularity of other small form factors such as the Raspberry Pi, VIA's pico itx boards or Zotac's Zbox caused a change of heart, but it appears this product is headed for the mainstream.

The Bottom of the NUC
(Courtesy of PC World)

What makes the NUC board so special?

Now functionally, as of right now, there is likely little difference between the end result of using one of the industrial boards I have previously mentioned or VIA's/Zotac's offerings, and this board, but there are some key differences that make this board 'special'?

1) MAINSTREAM

What mainstream means is availability to consumers via retail outlets.  This may not seem like a huge concern, but take from someone who has desperately tried to get the latest small form factor boards from industrial/embedded companies.  The first question they ask me is how many employee's my company has followed by asking if the number of board I'll need is in the 10 - 100 board range or the over 100 range.  Being able to obtain 1 board with retail support is a huge bonus.  While this is overpriced at $400, at least that includes the entire kit including the case.  I would also expect this price tag to fall in future iterations.

2) INTEL INSIDE (and its IVY BRIDGE)

While the Raspberry Pi is great for Arduino Fans and other ARM processors are Android ready, Intel and the x86 architecture remains the most versatile chip available.  Capable of running almost any operating system and it seems to be in intel's best interest to keep its hardware as operating system agnostic as possible.

This board is designed to have the most powerful architecture on it.  Although available in more powerful varieties, most small form factor boards are power-sipping, ATOM or FUSION based.  Not so here.  Yes, it is only i3 to start, but i5/i7 variants are supposedly in the works. 

3) EXPANDABILITY

At first glance the few USB ports and HDMI may seem paltry, but the one word that makes all the difference is THUNDERBOLT.  The next generation interface will allow for devices to be daisy chained as if they were part of the board itself.  Think of this as attaching daughter boards, if you want more usb ports, more display interfaces, more storage, no problem.  But, its even more, the PCI express speeds allow for connection to graphics cards is the need arises.  This allows you to build a board in any orientation and with whatever components you choose around a 4" square core.

4) GOALS OF USE

Despite the fact that it works, ECX/EPIC Boards are not intended for consumer computing and contain features that are somewhat wasted.  From security features to direct LVDS connections to dual gigabit ethernet to the ability to support a SIM card.  These proprietary features are usually left unused and in some cases even have to be disabled to make the boards more compatible.

All in all, I hope this board is a sign of things to come.  This is obviously a niche product, but most OEM computer products are niche at this point, from LED enshrined gaming cases to water cooling components.  The point is I believe that there is a market for people who want to incorporate powerful systems into small products and locations.  The smaller it is, the more extensive the options are.  But, I have to admit, I think the NUC would look fantastic in the base of an iMac G4.

Classic Merit Megatouch meets Classic Apple

The Merit Megatouch Bar/Table Top Game Machine

The Merit Megatouch Maxx (Saphire)

Megatouch Force

Maybe its nostalgia, maybe its a truly great piece of software/hardware, but I have always loved these machines.  I remember vividly playing photohunt at a local dive bar at a time when touchscreen technology seemed quite futuristic.  With less processor power than an iphone and resistive touchscreen technology that connected via serial cable, its amazing that I still see these machines being used frequently in bars and taverns.

Merit Ion Megatouch
(Courtesy of Jester's Amusements)

While I don't really know much about the various product lines that Merit offered, I do know that the most common machines I saw were the CRT Merit Maxx (with its jewel themed updates) and the newer Megatouch Force.

I'm putting together a game room and a Merit Megatouch was something I hoped to incorporate right from the start.  At first I looked at the modern LCD versions (such as the Aurora or Ion Lines).  In my opinion, the prices were astoundingly high for the level of hardware.  When I looked at older machines in various conditions, I again saw very high prices and a ver slow depreciation.  This didn't bother me so much, as it gave me an excuse to DIY it and truly make it my own.  Unfortunately, I found out that Merit does not license its software.  Thus, the reason for the high prices is really the software as well as excellent customer support from Merit.

Choosing parts is also somewhat of a pain as Merit is very protective of its software (as is its right).  Buying individual parts requires making sure your hardware and physical security key matches up with the Merit supplied hard drives.  The best bet is to obtain a working machine with defective screen and/or in physical disrepair, but functional inside (easier said than done).

So here is the motherboard:

Megatouch XL with Maxx Diamond conversion

Its technically and old Megatouch XL that was upgraded to the Megatouch Maxx
I again want to point out (both for my own protection and to state a fact).  This is a native Merit board, HDD, I/O card, and security key (the object with the battery and tag in the lower left corner of the motherboard).  The AT power source is new and replaces a defective one.  This is in NO WAY a hacked board and there is absolutely NO use of cracked or stolen/pirated or otherwise altered software.  Instead this is a genuine Merit Megatouch with some working parts (motherboard, I/O, HDD) and some non-working/damaged parts (powersource, touchscreen, CRT, enclosure) that I am replacing with available alternatives.

Booting is slow, the fan is loud, but it works

There is something very rewarding about repurposing old hardware that is otherwise destined for the trash.  This is especially true with "classic" hardware.  While "classic" is obviously in the eye of the beholder and difficult to define, to me it means, "a device that performs its original function in such a manner that it can not or at least has not been significantly improved upon, even if that function is currently considered obsolete."  With the iMac G4, from a mechanical engineering perspective, it "did its job" perfectly.  It allowed for nearly effortless manipulation of an LCD monitor.  Thus, making it easy to have the LCD conform to all potentially desirable viewing heights, angles, and tilt.  New technology may eliminate the need to change viewing angle to make a screen readable (IPS).  It may/will replace the need for LCDs with superior and more customizable viewing technologies (ex holograms, project glass).  But, if your goal is to have an all in one computer with a 15 - 20" LCD screen viewed on a desk, I don't think it has ever gotten better than the iMac G4.  People who love classic cars would likely say the same thing about their passion.  Similarly, Merit has barely changed the formula and, even in the iPad age, can still sell its touch devices for thousands.  This is because these Megatouch Machines "do what they do" perfectly.  They play simple, entertaining touch games that are both nostalgic and timeless.

The 17" ELO 1715L

A 300 watt AT PSU was easy enough to find for a few dollars.  The touch screen was somewhat of a happy coincidence.  The original touch screen was a 3M and I actually found an old touchscreen controller for this device.  However, I also an old 17" 4:3 LCD touch monitor from ELO.  While I was fairly certain the VGA would scale up easily to 17" from the original 15" CRT, I did not know if the touch screen would work or if I could calibrate it for 17".  I had forgotten that this particular touch monitor had both a usb and serial port option for touch control (I was planning on getting a USB to serial adapter), but did not need it.  It seemed to work, but clearly needed calibration.

First run - Touchscreen not Calibrated

The Menu Control connected to Momentary switch

I need to thank "Dark Paladin" and his work with Merit Megatouches.  In his project, which can be found here:

http://home.comcast.net/~dark.paladin/megatouch/

He reveals the 4 important pins including the two grounds at the top left and second from left, as well as the setup pin (top right) and Touchscreen calibration pin (second from right on top).  Using a momentary switch to temporarily ground these switches will send you to the Setup and Touch Calibration Menus respectively.  His design is definitely worth a read to anyone considering a similar project.

Touch Screen Working ... Photo Hunt Time

Some issues such as I/O, Sound, and Quieting the fan still need working out.

But the first thing to consider is the permanent housing.  The motherboard is way too bid for the iMac G4 and too wide for the iMac G5.  However, the other white plastic desktop of the era I feel would make an ideal home.  I am referring to the 17" Flat CRT based eMac.  Elimination of the CRT will give plenty of room for the PSU, Motherboard, I/O and HDD.  Cooling mechanisms and air flow are already present in the chassis.  In addition, my current 4:3 17" LCD should fit perfectly.  Despite this transition, because the CRT in the eMax is actually flat, it should be indistinguishable from the outside.

The I/O hub can be fitted with the momentary switches and the existing on/off button can be used.  The existing front speakers seem perfect for this mod.

Broken eMac = Future Megatouch?

Although it is bulky, there is a classic look to it and it will allow for a single contained unit.  I have picked up the broken eMac seen above.  The front bezel needs repair or replacement, but it otherwise appears to be in good shape.

All in all, I think this will make a very fun project while I await small form factor Ivy Bridge Boards for my new Pro iMac G4 mod.

Please feel free to ask any questions and as always, thanks for reading.
TO BE CONTINUED ........

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!!!

Options for a "PRO" iMac G4 Mod

When I began this project, my motivation wasn't just to retain the concept of the iMac G4, but to find a way to reuse the LCD screen.  I felt the same way about the iMac G5, and although their Power PC processors had become largely obsolete, the displays were more than adequate.

The 20" LCD was almost identical to the one found in the iMac G5 and in the aluminum 20" Apple Cinema Display (these are all TMDS and swappable).  The expansive 20.1" display had a 1680x1050 resolution as a result of a 16:10 aspect ratio.  The iMac G4 contained one of the first flat screen LCDs on an all-in-one computer at the 20" for the first for that size.  Then a funny thing happened, LCD monitors seemed to stagnate in many respects.  LCDs were remarkably sharp compared to CRT Televisions and as computers used small screens compared to TVs, I suppose many felt the resolution to be adequate.  Innovation continued in the form of LED backlighting and increasing screen sizes, but in some ways, resolution seemed to go backwards.

Courtesy of extreme.pcgames

I loved the 16:10 aspect ratio, you were able to see more of the page without having to scroll.  Having the extra vertical room was better for me in almost everything except for one thing - watching movies, an activity I rarely did on my computer monitor.  The extra horizontal space, look up more room on the desktop and went largely unused for me.  For many sizes there was a decrease in the area as well as a lower resolution.  The less pixels required for the same size made this especially appealing to manufacturers and for the most part 16:9 has become dominant.  For 20" the pixel loss was very significant, the 20.1" 16:10 1680x1050 as compared to the 20" 1600:900.  The result is that I have not seen any modern 16:10 20" LCDs at all, though 22" are common.

Higher contrast ratios, IPS screens, LED backlighting can not be found in a screen that fits within the existing housing of the 20" monitor.  What is more concerning is that tablets and smartphones, in particular the retina display of the iPhone and especially the iPad, have changed the way people view LCDs and pixel density is increasing in desktop displays once again.  Although Apple has generally been ahead of the curve with higher resolutions (began in 2009) on their displays, this is now becoming industry standard.

A good example is the evolution of the "smaller" sized iMac.  The 20" iMac G4 was released in 2003 and it was the largest size available and continued to be so into the iMac G5s and into the intel era right until the end of the white polycarbonite iMacs, where the 24" size appeared making the 20" the middle size.  The aluminum iMacs kept the 20"16:10 size with the larger 24".  With the appearance of the unibody aluminum iMacs apple went to the 16:9 aspect ratio.  However, they did not stick with the 20" size in 16:9 and the 1600x900 resolution.  Nor did they upgrade to the 22" 16:10 size and its resolution 1680x1050 (identical to the 20.1" iMac's resolution - thus actually less dense).  They went to a 21.5" 16:9 LCD that is true high resolution: 1920x1080 (1080p = HD).  There is now even talk of High DPI LCD Screens that go beyond HD.

The iMac G4 has 2 features that make great to use - its ergonomic arm and its LCD.  The ergonomic arm is especially useful with a touchscreen.  In my touchscreen variations, I have loved using this design and incorporating a touch screen remains my highest priority no matter which direction I go in.  However, as the LCD becomes more dated, I'm considering trying a radical redesign for my "Pro" Mod.  As of now these are the possibilities as I see them:

1) The 20" iMac G4 mod with some improvements:
- A better cooling system and processor/RAM upgrade
- Native PSU
- Touchscreen
- Possible iSight Cam

Four Possible Touchscreens

I discussed this in my Touchscreen post and I have obtained a 3M 16:10 20" capacitive screen that seems to work with OS X.  It has a significant thickness to it and can not fit inside the housing as is.
The easiest solution is to place it in front of the display or cut the front bezel (the bezel is about the same thickness as the capacitive touch overlay).  This should work and if done properly may not look bad.  I am worried about the weight and ruining the elegant look with a touchscreen jutting out somewhat.  Also,  placement of the controller and wiring down the neck would have to be worked out.

2) LED backlighting
I am currently working on this method and will discuss it in my next post.  But, the general idea is to upgrade the lcd with led backlighting which will allow me to use a thinner diffuser.  This may allow me to fit the touchscreen inside the LCD housing and will help alleviate the additional weight.

The iMac's Diffuser

Unfortunately 16:10 20" LED monitors do not exist, thus, I will have to alter a larger diffuser and backlight in order to fit in the housing.  I can't just add LEDs because the entire purpose is to use a thinner diffuser allowing for the touchscreen to fit.  In theory this method would allow the 20" iMac to have a touchscreen added without any notable external change.

3) New, Larger LCD with Custom Housing
- Adding a 21.5" screen would be ideal, high resolution screens with LED backlighting and IPS would truly be an upgrade.  Also, 21.5" LCDs with optical touch screens do exist and some of these can be multitouch OSX compatible.  But this wouldn't fit in the current LCD housing.  While it may be possible to enlarge the front housing, the back would have to be done custom.  While 3D printing and prototyping services are available, there are certain drawbacks to using the original design.
- The weight would be very different.  Also, the screen would likely use LVDS, so fitting the controller board so that DVI/HDMI would go through the existing TMDS wires in the neck would be advantageous.  Thus, the existing shape may not be ideal.
-  As the 21.5" screen is notably wider, it may start to look awkward.  Elimination of the surrounding clear plastic and wide bezel would help the proportions.
-  This would be very expensive and difficult to reproduce.

4) Redesign using a different LCD Housing:
- I have secured a different housing to the iMac before and made it into a successful mod.  So it can be done even with non VESA complaint monitors.

Apple Cinema Display Mod Housing Secured

- Obviously keeping the dome is critical.  It is what gives the iMac G4 its identity and allows the LCD to be pulled forward and rotated in a way that a base alone would not allow.
- The LCD housing would have to look modern, have an apple style, be able to fit a 21.5" LCD and have a weight and width similar to the original G4's housing.  While I know nothing about the weight issue, the obvious candidate is the housing from the 21.5" iMac.

- There are many technical details that would make this impossible.  But here is a very quick mock-up:

As I have the 20" touchscreen and have already begun, I am going to pursue the original design and housing with the touchscreen and LED backlight, but I may pursue the 21.5" based iMac in the future.  I would love to get opinions and suggestions, so please comment below.  Thank for reading.