There's one build that I've been wanting to attempt for some time now, I've just been too intimidated to begin. This is (to date) the least posted forum in the case mods section; and if you've ever looked at the iMac G4 mods, they look extremely complex. I always loved the iMac G4, it came in on the heels of the G4 Cube and was an engineering wonder, in my opinion. Right off the top, I want to commend the Dremel Junkie, JBerg, for his comprehensive tutorials available on his website. Without his efforts to share his vast knowledge of the G4 iMac, this project would have never taken flight.
I'm going to call this the NUCiMac G4, as it's going to utilize an i3 Intel NUC DC3217IYE motherboard/processor. It will have all the usual components in it, Apple BT & Wifi, mSATA storage, 8 GB RAM. One significant difference in this build over others I've seen so far is that it will operate with an internal 19V notebook power brick and a PicoPSU running off the stock power cord that shipped with the G4. I'm hopeful that the stock 65W PSU (that shipped with the NUC) will operate cool enough to run internally. This will provide the same clean "one plug" appearance that the iMac had natively.
I chose the 17" model over the larger 20" due to lower LCD power demands. The larger version creates power consumption challenges that would not allow me to run a single power brick internally. The 17" will push out 1440x900 resolution which is adequate for the usage I have planned for this system.
I found this pristine unit on Craigslist for 100 dollars. There isn't a mark on it, and the screen is perfect.
It was fully functional on OSX Leopard when I got it home, but it was very slow on that version of OSX.
This thread will contain the entire build log from start to finish. At the time of this post I'm about 1/2 way into the project, but am still waiting for parts to arrive for some portions of the build.
I'm hopeful that this thread will bring some much needed attention to the iMac G4 forum, and perhaps shine a spotlight on a machine that I believe really deserves it.
The iMac G4 was easy to tear apart. With the help of 8,10 and 15mm torx screwdrivers, it took little time to break it down. Theres A LOT in there! Apple was very clever in fitting all the hardware into a dome, every ounce of space was jammed with something.
The empty starting point for my NUCiMac. Three cables come down out of the LCD screen, they are (in order left to right); the LCD cable, the inverter cable and the microphone cable (the only one that I will not re-use). There is plenty of cable length to comfortably work with the cables during the mod.
Wow! A ROUND motherboard! It MUST be an Apple Product! I would later actually re-use part of the motherboard.
The native PSU was actually divided into to parts that resided in both halves of the upper dome. They were connected by a cable. One great feature was a 2-pin plug (shown at bottom left of photo) that allowed easy unplugging of the motherboard when opening up the machine to work on it. I liked it so much that I decided to later re-use this cool feature in my build implementing the 2-wire plug.
Deciding where and how to seat the NUC system board took a fair bit of thought processing. I ultimately decided that the most functional and aesthetically pleasing location would be in the space held by the previous DVD drive. There is mixed opinion on scrapping DVD drives, but in this build with it's limited workspace, the DVD had to go. In all honesty, I have a USB DVD writer that I only use maybe a couple of times a year. Its compatible with OSX, so why waste nearly a precious 100 cu in of internal space on a redundant piece of hardware that can easily be managed externally by USB?
To affix the the rear I/O in position, I decided to cut out a piece of the original G4 motherboard, preserving four of its mounting holes for fastening to the base of the machine. This allowed the rear I/O to remain firmly seated with little re-engineering. Apple had already done the legwork for me, so why re-invent the wheel? I ground off all the capacitors, memory slots etc with my dremel. I gave the original board a real 'clean shave'.
Here's what the original board looks like now, after I painted it black. Several of the rear I/O pieces would later be removed off the board to fit my own. There isn't much left of the original, but what matters is that I preserved four mount holes for a firmly seated fitment.
Here's whats left of the old motherboard. Didn't this used to be round? Rest in Peace.
I then cut a plate of aluminum to fit the base. It is drilled to mate up with three of the four motherboard mounting holes. I used UK Electrical Socket Screws (trimmed to correct length) as the thread pattern matches that of the standoffs in the base. These work great in the Apple mods, and I alway keep a package of long ones on hand for re-purposing. They are readily available on eBay. I chose this shape of mounting plate because it leaves access open to the rear I/O, and doesn't impede the critical airflow that will come in through the base vents all around the bottom of the machine, and doesn't collide with the front DVD door. I used the original NUC base to mount the board. It is mounted firmly to the aluminum plate with 2 bolts as shown. (Note that I hadn't painted the G4 motherboard yet in this photo).
Rearward view of NUC base mounting
To secure the motherboard to the NUC base, access is required from underneath. I drilled four holes in the underside and through the aluminum mounting plate to allow screwdriver access for tightening down the NUC board. It is secured at the top with four original standoffs removed from the NUC case.
The four screwdriver access holes in the bottom (only 2 are really visible)
The NUC firmly secured down using four of its own original standoffs (now on the top) via four screwdriver access holes underneath.
I took this photo through the DVD door. It shows the new interior space for the Intel NUC in the original DVD drive location. The new floor sits within about 2mm of the DVD/HDD rack at the bottom, very close measurement paid off. The aluminum floor still had the protective plastic peeling on it, thats why it appears so white. This looks like a great new home for the NUC to live!
The base installed in the iMac viewed through the DVD door. The NUC fits perfectly in the previous DVD drive location. There is about 1/8" of clearance between the NUC cooling fan and the G4 Hard Drive rack above it. Wow it was tight, but it all fit in there!
Last edited by ersterhernd; 07-14-2013 at 01:18 AM.
The photo below shows how effective it was to leave a piece of the original motherboard intact. It shows the re-purposed I/O with three USB 2.0 ports, and a power switch that will operate using the original iMac G4 power button on the rear. I used liberal amounts of JB Weld to secure the inner components to the original motherboard, as there could be significant force applied from the exterior when inserting USB devices. I haven't figured out the ethernet port yet, as there is VERY little space on the right side of the power plug. Two firewire ports were re-purposed into a horizontal USB port. The blue standoffs for the aluminum plate are from the LaserHive that I had leftover from a previous build. Two per hole gave a perfect height for the installation into the system. Did they look familiar, MiniHack?
There will likely be more re-purposing of the rear I/O to accomodate the ethernet jack and some form of audio jack in a clean presentation.
Last edited by ersterhernd; 07-14-2013 at 09:47 AM.
Reason: oops! Spelling mistake!
One of the primary goals of the NUCiMac project is to utilize a single 19V DC Power Brick internally. It will supply both the NUC and also a Wide Input PicoPSU that will send required power to the LCD and 92mm Noctua Case Fan. The NUC comes with a 65W version as part of the retail package, so I will try that first. The big question early on was "Will this be enough power?". I know from my G4 Cube PSU build that the NUC draws around 25W on max load, what I didn't know was how much power the 17" G4 LCD was going to draw. This pressing question had to be answered before I started building the computer.
Unfortunately I do not have my PicoPSU yet, so I grabbed an old ATX PSU and my Kill-A-Watt meter out of the closet to conduct a power test.
Step one was to wire up the inverter in the G4 so I could power up the LCD backlight and test the wattage draw. Following the instructions on the Dremel Junkie's website (thanks again, JBerg!) I had the inverter cable disassembled and wired into the ATX PSU in about an hour. I used temporary wiring and alligator clips for this part for testing purposes only. A permanent and clean solution would be built upon success. The photos of the process are shown below.
EDIT : I have modified the inverter wiring slightly different from The Dremel Junkie's layout. See this post for details.
Inverter Power Draw Test Photos. The first pic is the inverter cable disassembled.
There are four wires to be connected, with a 1K Ohm resistor inserted into one of the lines. This photo is the temporary wiring only for testing purposes.
Perfect! A fully functional LCD backlight!
The power draw from the LCD and 92mm Case Fan -- Under 33 watts. Sorry for this poor quality photo, it reads 32.3 on the gauge.
Once I knew for sure that it worked, I built a cleaner final solution for attaching the inverter cable directly to the PicoPSU. Two photos of the completed inverter cable connection are shown below. Connecting it will be as easy as plugging four wires into the Pico.
The physical mounting of the internal power brick required JB Welding a small piece of aluminum angle bar to the G4 HDD/DVD rack. This created a perfect rubber-lined cradle for the 19V power supply to seat firmly up and out of the way. The green arrow points to the 19V power brick in it's new home.
Cabling to the internal Power Brick is wired through the stock G4 plug via the stock G4 2-pin PSU power connector. The earth wire fastens to the case with one screw. Connect/Disconnect takes about 20 seconds.
Cabling coming out of the internal 19V power brick goes to the NUC and to the PicoPSU. I'm still waiting for one more male 5.5mm/2.5mm socket plug that will be wired onto this setup for split power to both destinations. The photo below shows the empty taped-off lead waiting for the additional male end.
The Completed Power Loop for a totally internal solution
Last edited by ersterhernd; 07-25-2013 at 12:49 AM.
With the dual internal PSU's that will run in this system (19V Power Brick and PicoPSU) there needed to be a method to start both PSU's with a single push of the power button on the rear I/O. I created a setup that uses a 5vdc relay that will be triggered from USB power on the NUC. When it trips closed, two lines connected to the 'ON' and 'GROUND' on the PicoPSU will automatically start (or shut down) the PicoPSU. This will accomplish the 'One Button Press' to effectively start the machine, and will power the entire system down when USB power is off on the NUC motherboard. I send thanks to MiniHack and iCubeFan for assisting with this idea.
EDIT: I discovered that I don't need to use a USB connection for this. Instead, I used pin 9 of the Front Panel Header, which supplies an identical 5V that the USB pin did. For ground, I connect to a GND connection on the PicoPSU. Now I have an extra USB header available that can be used for something else.
EDIT # 2: Thanks to MacTester57's advice, I've installed a simpler and totally silent solution (no relay 'click' sound) shown below using a BC547B transistor. Total cost was about 25 cents and it works flawlessly for powerup, sleep, rewake and power off.
Last edited by ersterhernd; 09-22-2013 at 10:43 AM.
Reason: New Information