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Ersterhernds iMac G5 (iSight 17) Project

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A Little History

Hello everyone, first a brief introduction to my iMac G5 iSight 17". I rescued it off Craigslist last year for free by answering a local ad as shown below. As advertised, it didn't work because there was no image on the screen. The backlights came on just fine, however, so I figured I'd give it reset (PRAM and SMC) to see what happened. The good news is that it immediately came back to life. A quick update to 10.5.8 and it was good to go.





We used it here on the kitchen counter for several months. The machine is a pleasure to use; compact, quiet and uncluttered because there's no additional cables anywhere. Perfect for a clean look on the island in the kitchen. A couple of weeks ago, unfortunately it lost it's screen image again and regardless of the PRAM/SMC resetting method, it never regained its functionality.

The question now became 'what to do with it?'. We'd grown quite fond of the system from the use we'd made of it, and I didn't really want to just throw it away or part it out. Aesthetically it's terrific. Could it be a mod candidate? :think:

I set to work to see exactly how this machine would stack up as build project.


Initial Observations & Questions

First and foremost; in their usual fashion, Apple did an incredible job of fitting all their hardware inside this thing. It was sad to have to rip out all of their handy-work, but didn't take long to get the iMac down to an empty shell. I disassembled everything carefully without damaging any cables, connectors or other hardware.

In my observation of the gutted system, it became obvious that there would be four key 'hurdles' that would need to be cleared before any success could ever be achieved, and that spending any money on this mod wouldn't happen until I found a workaround for each of the four challenges.

I'll list them off...

1. Video. The proprietary TMDS video connection from the 17" LCD to the iMac G5 logic board is small and essentially unworkable (in my opinion) for anyone but an absolute expert with a soldering iron.

2. Rear I/O. The ports (including AC power) on the back of iMac would need to be re-used in their original form, due to the shape of the exterior shell and their precise mounting angle on the iMac logic board. Repurposing the rear I/O as I've done in each of my iMac G4 builds wouldn't be feasible here, there simply isn't enough room or means to do it.

3. Fitment. Would an Intel NUC and PSU even fit? If the machine won't close up, it's useless.

4. Cooling. Could efficient airflow be drawn inside the iMac to properly cool it in a modded form?


Fortunately, I found answers to all of the above. This project is a go. As it turns out, this 17" iSight model is surprisingly turning into a great candidate for a mod. I will cover each portion of the project in a Build Log for the sake of clarity, with full explanations of my rationale.

Parts are ordered, and should start arriving in a week or two. As is with all mods, there is no guarantee of success, and from what I can tell there isn't a fully completed example of such a mod as this avaiable for my reference. I'm hopeful that it works, and at this point I'm fairly confident that it will.



Ersterhernd
 
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Build Log 1 — Hardware Goals

This is a brief outline of what my iMac G5 should look like at the end of the project. If problems arise, this list will be subject to change. I will say that the goal for the system is to achieve the same compact, quiet and uncluttered machine that we enjoyed with the original. It will be used in our kitchen, primarily for light applications, internet, email etc. Ethernet is not required, only WiFi, and due to issues that I discovered with the iMac G5 native ethernet port, thats a good thing. I’ve also set a goal of keeping the cost of this build as low as practically possible.


The proposed list is as follows...

- Intel NUC DC3217BY with i3 processor
- 4 GB 1333 DDR3 RAM
- 64 GB mSATA Crucial SSD Storage
- Apple A1181 Bluetooth
- Broadcom ’N’ Series WiFi
- Internal NUC Power Brick (65W)
- Internal PicoPSU WI-25-120 PSU
- BC547B Transistor actuated PicoPSU on/off control
- Adjustable slider on bottom of the iMac for LCD brightness control
- Picaxe 08M2 Micro-Controller for pulsing sleep using original iMac LED
- MiniDisplayport to DVI converter with MOLEX PN 74320-4004 connector
- NZXT IU01 internal USB Hub
- Original iMac cooling fans x 2
- StarTech ICUSBAUDIO Stereo Audio Adapter
- PAM8403 Mini Digital Audio amplifier
- Internal iMac Speakers
- Internal Microphone utilization
- Apple iSight Camera
- Apple IR Receiver
- 3 x USB 2.0 external port
- Original Power Plug
- Original Power Button
- Hard Reset button
- Apple BT Trackpad and BT Wireless Keyboard
- No Ethernet Port utilization
- No DVD-ROM installed



Ersterhernd
 
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Build Log 2 — Layout Map

The iMac G5 iSight model is a quite different from the non-camera version. The internals are accessed by removing the front bezel and the LCD. This leaves the computer internals accessible while mounted in the machine in a stand-up position. I originally thought it would be a pain to work with, but as it turns out it is an absolute gem. The iMac can be left in it’s normal stand-up upright position with full access to all the components. Its a breeze to work on.


This isn’t my image, but shows the iMac components accessed in their original form. The iMac in the photo is identical to mine.





This is my iMac G5 in it’s current state with a few modifications already completed. I’ve labeled the basic map for repurposing. Note that the iSight version (as stated above) is very handy to access for a mod, because it’s stand-up position puts the components right at working level, rather than laying flat. I’ve found this much easier on my neck and back, so far.

Note that with everything installed as shown, the iMac LCD still fits perfectly on top of everthing and the front bezel snaps into position just great. :thumbup:

1. NUC PSU and mount brackets
2. Intel NUC inner metal casing
3. Main Intake Fan
4. NUC Cooling Fan
5. PicoPSU & TMDS/DVI/MiniDP Conversion
6. Cut-down I/O section of original G5 Logic Board
7. LCD brightness adjustment slider & USB Audio with Amplifier
8. Excess cable storage area
9. Left Speaker
10. Right Speaker and iMac LED
11. A1181 Bluetooth and Wifi Antennas







Ersterhernd
 
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Build Log 3 — Video Connection Planning

The iMac G5 iSight uses a proprietary cable to link the tiny TMDS wires from the 17" LCD to the Logic Board. A sample image is shown below. The connector at the logic board end is essentially unworkable from a modding standpoint, in my opinion. Video signaling is very fussy and stable connections are essential for a clear output to the LCD. My limited soldering skills would likely never be suffice to complete the required modification from TMDS to DVI with any success. A suitable workaround had to be found.


The original iMac G5 TMDS cable with proprietary Logic Board connector. It affixes to the logic board with two Torx T-6 screws.





I removed the tape from the LCD connector end of the cable, and made a very interesting discovery. The TMDS wiring appeared to match up exactly with that of the iMac G4. I have an old broken 17" G4 LCD here, so I tested the G5 cable fitment by plugging it into the G4 LCD. It fit perfectly.

This is where it gets interesting. I asked myself, "Could I wire up the TMDS from the iMac G5 to DVI using an iMac G4 cable?". The G4 LCD cable contains connector pins that are proven to be workable with the proper DVI conversion connector.

I looked up the exact pinouts for the iMac G4 and iMac G5 LCD's for TMDS comparison. Heres what I discovered...



iMac G5 LCD Pinout Diagram




iMac G4 LCD Pinout Diagram




From what it appears, they are pin compatible, and the actual metal connector looks nearly identical with the two clasps. This could be the successful path to connecting the G5 LCD to DVI, simply by using the #661-2825 TMDS cable found in the 1.25 GHz iMac G4 neck. I figured it is certainly worth a try, so I ordered the neck for 50 dollars (shipped) from PowerbookMedic in the USA.

The Intel NUC DC3217BY that I've ordered has both a ThunderBolt port and an HDMI port for video. I have parts already here for a MiniDisplayPort connection to TMDS, so I'll try that first. If it doesn't work, I'll use an HDMI to DVI to TMDS method, but I don't think I'll have to. MiniDisplayport apparently works just fine in a Thunderbolt port.


The mDP to DVI to TMDS plan. The iMac G4 661-2825 LCD cables will connect the iMac G5 17" LCD to the Molex part number 74320-4004.




Hopefully (fingers crossed) this will provide a clean connection from the Intel NUC to the iMac G5 17" LCD.



Ersterhernd
 
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Build Log 4 -- Rear I/O

The rear I/O of the iMac G5 is designed to mate up presicely from the logic board to the rear of the outer shell. There was no visible method that I could think of to re-create this on my own. The logic board had to be used to accompish the task. I cut out one corner of the original Logic Board, retaining as many of the fastening holes as possible and keeping the entire rear I/O intact.


Note the angle that the I/O is mounted to the Logic Board, its not at a straight 90 degree angle.





Wired Ethernet Issues

I originally planned to use the 3 USB 2.0 ports and the Ethernet port. The others I simply didn't need. I ran into problems with the ethernet. Apple has implemented some kind of ethernet jack that I've never seen before. When I put my multimeter on the 8 ethernet pins soldered into the logic board, I got ZERO connectivity to any of the wires contained in a small piece of ethernet cable that was plugged into the port.

With a little searching, I found out this is no ordinary jack. Here's the link...

http://www.datasheets360.com/pdf/8363465782469285383


Here's the pins that my multimeter showed as dead in all tests. Apple must have engineered something into the logic board to activate them, I'm not sure. Maybe I missed something, I don't know.


A note about the Intel NUC...

It was for this reason that I decided to go with the NUC DC3217BY version (non-ethernet) rather than a more expensive version. The DC3217BY is apparently quite un-loved, because it's price has dropped dramatically (less than 200 dollars CDN) compared to its ethernet counterpart which remains about 50% higher to buy. This iMac is going to be a kitchen system anyway, where we don't have any ethernet installed, so WiFi will be the means of connectivity for it anyway. The bright side? I saved 150 dollars. :thumbup:


USB 2.0 Ports

The I/O connectivity to the outside world via USB is essential for any build, this iMac was no different. There are three native USB 2.0 ports on the back of the computer, and I wanted full functionality of them all. First, I tested resistance between them on the Apple G5 logic board using my multimeter. I found that the GND and 5V were common on all three ports, which would render them useless in my application. To circumvent this, I used a sharp razor knife and scored deep cuts around each set of four solder points on each port. This solved the issue, yielding individual ports without any cross-talk between any of the three.


The six scored markings in the Logic Board to solve the common GND and 5V cross-talking issue





The next step was tedious. I had to solder connecting wires to the tiny pins of each port on the logic board. Damaging the tiny traces would render a port useless, so great care had to be taken. A photo is shown below of the soldered connections. The USB ports are tested and fully functional via this wiring. Note that I ran out of red wire, so had to use two blue wires in place of red for the 5V of two ports.






To eliminate stress on the wires, and any possibility of breaking off the tiny soldered joints, I kept the connecting wires short and mounted firmly with 3M sticky pads. This provides a simple method of connecting extension cable to the three USB ports on the Intel NUC. (Ignore the orange and black wires for now, more on those later). ;)


The USB wires with the right side speaker installed. Nothing is pinched or stressed.





Ersterhernd
 
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Build Log 5 -- LED Functionality

One of the unique features of the iMac G5 is the subtle LED that shines in a crisp white circle through the front of the plastic bezel. I wanted to preserve that function, including the pulsing 'breathing' sleep feature when the machine in is sleep mode.

I went to work with my multimeter to find two connections (+ and -) somewhere on my piece of cutout logic board to power the LED. Soldering directly to either side of the LED not only risky, but would likely block the right side speaker from mounting correctly, as Apple designed the plastic to fit flush up against the Logic board with a small 'light tunnel' that encircles the LED to produce the crisp circle of light. Its a very clever design, typical of Apple.

After a lot of searching, I found two locations for the power and GND. They are both shown below.


The LED GND connection




The LED PWR connection (PWM, 3.3V or 5V all work well). Note that this is on the reverse side of the Logic Board from where the LED is located.





To emulate sleep, I incorporated a PWM signal supplied from a Picaxe Micro-controller. The functionality is described at this link. I created a strip board for the circuit, with 5 necessary wires connected to it. I used a regular ATX PSU to test the functionality. It works great.


The Picaxe 08M2 micro-controller installed in a circuit board for LED control




The iMac G5 LED shown operational. Note the soldered GND connection at the location specified above.




LED shown throught the 'light tunnel' that Apple designed into the iMac G5





I tested several brightness levels for the LED. My plan is to have it stay on continuously during normal operation and pulse during sleep. For continuous operation, I prefer just a very subtle dim effect with the LED set to about 25% brightness. For sleep 'breathing' it pulses between 5% and 100%. Of course, these levels are easily adjusted through software that the picaxe chip uses. Credit goes to MacTester57 for perfecting the pulsing LED code.


Continuous LED (during normal operation) set to a subtle dim level. Very unobtrusive for use.




Video of the sleep function tested with an ATX PSU

[video=youtube;HU7zVwWL3sc]https://www.youtube.com/watch?v=HU7zVwWL3sc[/video]




Ersterhernd
 
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Build Log 6 -- NUC Fitment

The DC3217BY is ordered, but may take a week or two before it arrives. I've got an inner metal shell from a DC3217IYE NUC that remains unused and is the same size as it's brother, so I used that for test fitting into the iMac. I was pleasantly surprised that the the LCD panel fits on top of it with about 1/8" of clearance. These iMac G5's get thinner towards the outer edges, so I wasn't sure if the NUC would fit or not. I still haven't figured out how to actually attach the NUC inside, but that shouldn't be too difficult.







The center intake fan (an original iMac G5 part) will blow beautifully into the NUC's metal shell after installation. One side of the NUC casing will have to be dremelled out, but this setup should provide excellent fresh airflow directly over the NUC's i3 CPU. I was very pleased about the way this worked out, you can see from the photo below that the trumpet output of the fan looks like it was made to cool the NUC. Perfect.






Ersterhernd
 
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WOW!!!

Great too see you tacking this project as well, although as you said these are very different machines and our approach is likely to be very different, but will help where I can.

My goal was to try and retain as much of the original including CD and DVD. You have removed most of the original components. IMHO there wouldn't be enough space in the 17" if you had retained those

I plan to solder my LCD cable to an HDMI socket, will post picture. Please save the original LCD cable it may come in handy if I come to grief.

The ethernet socket has little transformers in it, which isolate the internal and external connections. This I assume is to protect the main logic board from power surges/lightning etc, it will just fry the socket.

You should be able to solder to the ethernet socket and it should work even though a residence checker shows open circuit, the two centre pins of the 10 should be grounded.

Can you post a PIC of the Inverter board ?
What Voltage does the Inverter take, and how will you provide this ?
In you diagram in post 3, are the fans #3 and 4 the original fans ? EDIT Your latest post answers this
Are they standard 12V PWM (pc like) fans, or the custom voltage controlled apple ones ?

Anyway you will likely be finished before I am, you are already well ahead on the build phase.

Kiwi
 
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Hi Kiwi, thx for the reply.

The soldering of the tiny TMDS wires is WAAYYYY beyond my ability. Good luck with it, I hope you get a clean signal. It'd be a first, thats for sure.

The 17" iSight inverter is at this link, theres a photo there. Four wires come out of it attached to a small plug-in type connector that plugged into the logic board. I've tested the operation successfully at 3.3V, but not with a PWM signal yet to vary the voltage. My plan is to install a little Grove Slider under the iMac so the user can simply move it right or left to increase/decrease the brightness. If it doesn't work, it only cost me 12 dollars.

The four inverter wires are shown below. There's 3 of them that are black so care is needed to hook up properly. The 12V, 3.3V (with Grove Slider) and GND will all come from the PicoPSU. I'm thinking that the other black wire is for on/off or something during display sleep. I think it'll be left floating.





The two fans that I'm using are the Apple controlled type. Pinout is below...

Brown - 12v
Black - GND
Gray - Floating
Black/Gray - 3.3v or PWM (these fans require 2.7v to start up I think)

I've tested them using a 3.3V supply to the Black/Gray reference wire and the fans are quiet yet move a lot of air. I'm thinking at this point that PWM won't even be necessary if the airflow is sufficient at 3.3V reference. After all, they're only cooling an Intel NUC, not a full logic board and PSU like before. Time will tell.

As far as the ethernet socket goes, I've already ordered the non-ethernet NUC, so I don't think I will waste any energy on trying to get it to work. The USB ports work terrific re-wired, thats all I really cared about.


Looking fwd to both of our G5 builds moving ahead.


Cheers!
 
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...

The two fans that I'm using are the Apple controlled type. Pinout is below...

Brown - 12v
Black - GND
Gray - Floating
Black/Gray - 3.3v or PWM (these fans require 2.7v to start up I think)

I've tested them using a 3.3V supply to the Black/Gray reference wire and the fans are quiet yet move a lot of air. I'm thinking at this point that PWM won't even be necessary if the airflow is sufficient at 3.3V reference. After all, they're only cooling an Intel NUC, not a full logic board and PSU like before. Time will tell.

As far as the ethernet socket goes, I've already ordered the non-ethernet NUC, so I don't think I will waste any energy on trying to get it to work. The USB ports work terrific re-wired, thats all I really cared about.

Looking fwd to both of our G5 builds moving ahead.

Cheers!
It looks like your fans are similar to the ones in the non-iSight (my) model. Even the colour of the wires are the same, See my post on the subject (Note: I mis-identified the Black/Grey wire as just Black

For your reference:
The Brown wire is a 12V reference voltage, there is no current drawn on this wire
The Grey wire is a tachometer, and can be used to measure the actual fan speed.
The Black/Grey wire is not PWM, it is the main current drawing wire. The voltage controls the fan speed.

See my post for more details

http://www.tonymacx86.com/imac-mods/107859-kiwis-next-project-imac-g5-4.html#post681755
 
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