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Kiwi's Next Project - iMac G5

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Note: If you would like to see the final result of this build follow this link: http://www.tonymacx86.com/completed-mods/139633-kiwis-20-imac-i5.html

Just though I would let you know of my latest purchase.

http://www.ebay.com.au/itm/Apple-iMac-1-8GHz-PowerPC-G5-20-/321189563951?nma=true&si=oZqeAXHDBUQHbgRCZpreJEqH8cw%3D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

Its a PowerMac8,1 (A1076) with 1.8GHZ G5, 1GB Ram, 240GB HDD, and 20" 1680 x 1050 screen.

Plan to NUC this one, but will wait for Haswell boards to come out. Since this is the first G5 iMac model (computer integrated in display), I am hoping there are enough similarities with the lampshade model's to leverage work done so far. Note: I have been looking for lampshade model also, but just cant get them down-under.

Will post a couple of pics after I pick it up.

Kiwi
 

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Good luck with this one Kiwi.

My first Haswell board arrived today (Zotac h87 itx) so I'll be playing with that one soon. Going to do Ubuntu first to do all of my usual DSDT table fixing before I try any other OS on it.

I'll be interested to see how much room is in the G5 iMac, but expect it'll probably be NUC friendly (as they seem to fit inside everything!).
 
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Good luck with your new project, Kiwi

I would recommend to do some measuring (which wire has how much voltage in every operating state) on the inverter etc. before you disassemble the iMac. I did that and was able to reveal the secret of the G4 inverter. The result was the probably first iMac G4 Hackintosh with a working CCFL dimming!

Can't wait to see your progress.

MacTester
 
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Enjoy every step of the project, Kiwi.

Looking fwd to seeing it progress.


Cheers!
 
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I'll be interested to see how much room is in the G5 iMac, but expect it'll probably be NUC friendly (as they seem to fit inside everything!).
I think there is a good place to put a NUC, basically where the existing G5 CPU and memory sit, the killer is going to be the height. I measured and found only 28mm from the mid frame to the back of the case. Attached picture shows 25mm + 3mm gap to the back of the computer.

It is clearly unlikely that a mini-ITX board would fit, even a thin one, my Self build needed close to 40mm of height. My probable option is to cut into the mid-frame to allow tallest components some extra room.

If anyone (with a NUC) can measure the total thickness of the NUC board without case, from heatsink to highest component on the component side of the board ? would be appreciated.

I would recommend to do some measuring (which wire has how much voltage in every operating state) on the inverter etc. before you disassemble the iMac. I did that and was able to reveal the secret of the G4 inverter. The result was the probably first iMac G4 Hackintosh with a working CCFL dimming!
Good advice, one of the reasons this is a good machine, is it was the first G5, replacing G4, hoping there are similar components. I intend to do a lot of planning and testing on this one, main challenges will be reuse of main PSU, reuse of rear IO ports, connection of LCD and inverter.

Enjoy every step of the project, Kiwi. Looking fwd to seeing it progress.
Cheers!
Thanks, I cant promise this will be as fast as your builds.
 

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If anyone (with a NUC) can measure the total thickness of the NUC board without case, from heatsink to highest component on the component side of the board ? would be appreciated.
Kiwi,

The NUC's inner sheet metal case - which I recommend to reuse - is about 34 mm thick. The thickest point is from the hump in the heat sink area to the point where the HDMI connector sits.

In the G4, the NUC fits perfectly in the space where the 3.5" HD was. However, it's about 8mm thicker. So I had to remove a part of the drive cage and even a part of the DVD drive itself to allow the usage of the internal 19V header. See here: http://www.tonymacx86.com/imac-mods/104625-mactester57s-hemimac-g4-7.html#post650195

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Kiwi,

The NUC's inner sheet metal case - which I recommend to reuse - is about 34 mm thick. The thickest point is from the hump in the heat sink area to the point where the HDMI connector sits.

In the G4, the NUC fits perfectly in the space where the 3.5" HD was. However, it's about 8mm thicker. So I had to remove a part of the drive cage and even a part of the DVD drive itself to allow the usage of the internal 19V header.

MacTester
Thanks

I have been doing some more reading about the Haswell NUC, according to one article it been slimmed down, by almost 5mm (size of the case). HDMI has been replaced with mini HDMI, usb ports rotated, and ethernet port sits in gap in board. This must translate into a thinner overall board

At this point I have to assume it will fit into the 28mm that I have. If when I get one of these it doesn't fit, will look to cut some holes in the mid-frame to allow the tallest components to sit down a little lower.

Cooling will be a challenge. Will post some layout pics latter

Some Articles on New NUC:
http://www.legitreviews.com/intel-nuc-kit-d54250wyk-spotted-at-pax-prime-w-haswell-cpu-inside_122531
http://www.hardwarezone.com.sg/tech-news-intel-extend-nuc-next-unit-computing-family-haswell
 
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Part 1 - Introduction

In Australia, you really don't get the same choice of what you build, on PowerMac's are freely available, you have to take what is available when it comes to Cubes, and iMacs, in year and a half I have building this is only the second computer available on eBay

I Purchased a first generation 20" iMac G5 (white) model, for really three reasons:
  1. The LCD used in this case is confirmed (by DremelJunkie) to be compatible with his G4 modding techniques.
  2. Easier to work on. You remove the back panel exposing all the computer components, in latter models access was via the front of the computer, which means LCD must be removed first. Latter models are also thinner.
  3. I choose the 20" (over 17") because it is a bigger screen, which also means more room inside the case.
GOALS
  • Basically keep as much of the original as possible, no outward change.
  • Keep internal componets i.e. PSU LCD FANS Inverter
  • Backlight dimming via SW (OSX) control.
  • Internal 3.5 inch HDD
  • Optical Drive
  • Internal WIFI / Bluetooth / Speakers
  • Sleep LED.
  • Startup Chime - Not priority
A Haswell NUC was chosen, based on preliminary information it:
  • Has a SATA Port to drive internal HDD
  • Runs off 12V Power source (which the native G5 PSU provides)
  • Thinner, every mm counts!
Here is my layout plan, as you can see I wish to keep (in Green) a lot of the ancillary components, PSU, fans, etc. The really is only one place the NUC can go, but its placement leaves 4cm top an bottom for all the external connectors. There also is a lot of space above the PSU for other conversion components (Picaxe, Pico, etc).

It would be good to the CPU fan to function as intended to suck air through the NUC's heatsink, will need a mod to the existing shroud, or even a new shroud, but would remove the need for the NUC supplied fan.
 

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Part 2 - Power Supply

I have been doing some investigation on the reuse of the G5 PSU.

The PSU is essentially an ATX PSU, it has the usual 3.3V, 5V, 12V lines, is almost pin compatible with ATX, includes a standby 5V source. So need for a Pico PSU.

The PSU has a 24V power line, to power the inverter (of course), so I don't need a 24v up converter.

And the really good new is that the Haswell NUC power input has gone wide range, and supports a 12V input. This means I dont have to worry about 19V at all. I have checked the specs of the PSU, it can supply 78w on 12V, which is more than ample to supply the NUC. Reviews state the latest Ivy Bridge i5 NUC consumes 40w under high load, assume Haswell will be lower than this for comparable processor.

Unfortunately the Nuc doesnt have an ATX power input. It has a single DC input, which it assumes is always on. The NUC itself (without aid of PSU) turns itself on and off.

This poses a delema, do I wire the G5 PSU to be always on ?

I would prefer not to to have to do this. Simply leaving it on all the time could be detrimental to its life (already 10 years old). If you search for "iMac G5 PSU" you get lots of links about how to replace the capacitors. Not a good sign.

Part 3 - Power Management

The solution is a micro controller (powered from G5 PSU standby 5V) will have responsibility for power the machine on.

It would wait for user to press main power button. Then it would power the G5 PSU on, and initiate the Power switch on the NUC, turning the NUC on. Once on it could pass through the signal of the main Power switch to the NUC to allow the user to switch the NUC off. When it detects the NUC is powered off it could power down the G5 PSU automatically.

The MC will also control other system functions that the Motherboard cannot, like the LCD Brightness, Case fan speeds, Sleep LED, Startup chime, etc.

The micro controller will be connected to the machine via USB, so software running on the Mac will allow the user to set the screen brightness (just like real mac). The USB connection will also allow the firmware on the MC to be re-flasshed.

This device will be very much like a PMU of earlier Mac computers.

Problem:

The problem with this solution, while ambitious, if the micro controller gets corrupted, then no way of turning the machine on !!!

Feedback welcome, just an idea at this stage.

UPDATE : For reference this design was changed. Please See this Post for details
http://www.tonymacx86.com/imac-mods/107859-kiwis-next-project-imac-g5-3.html#post666896


Kiwi
 

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Kiwi,

Your layout plan and the logic diagram look good. Reusing the old PSU will work, but as you said it's old and could break.

The problem with this solution, while ambitious, if the micro controller gets corrupted, then no way of turning the machine on !!!
I think, that should be no problem, if the Picaxe wiring is done in accordance with the manual. You should do a test on a breadboard, before you disassemble the iMac and test the desired functionality. The Picaxe micro controllers have limited multitasking abilities (depending on the chip type), if the PWM functionality is used.

Picaxe microcontrollers appear to be the new standard in iMac mods. ;) :thumbup:

Can't wait to see your progress

MacTester
 
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