Contribute
Register

An Amazing Find for My Next Project -- iMac G4 20"

Status
Not open for further replies.
MacTester57 said:
WOW, looks good, but I'm afraid you will not have time do do your mods, if you do the support for your elderly neighbor.... :headbang:

MacTester
Click to expand...


Haha! If you think it took patience to mod an iMac G4, MacTester, you should try to teach a sweet old lady to use OSX! Actually it's a pleasure to teach her. Additionally, she can reach my wifi signal for free from her house next door, so this costs her nothing with a tremendous benefit for her. I really think it will open up her world significantly, that's why I did it.


Happy New Year!


Ersterhernd
 
Build Log 1 -- Initial Inverter Voltage Testing

Step one of this project is to measure the inverter voltages while the system is still functional as a G4 running OSX Leopard. Once the system disassembly begins, its not possible to gather this type of information.

I've completed initial testing of the Inverter power for the iMac 20" G4. I had to disassemble the screen and remove the inverter from its bolted position behind the LCD. The 8 pin plug is on the underside of the inverter when its mounted in place, so complete removal was necessary from the LCD housing. Also, the screen flickered uncontrollably at higher brightness levels with the inverter unbolted, due to a grounding issue I figured. Once re-installed, the flickering went away. During testing, I attached a temporary 'ground wire' to each of the four bolt holes of the inverter. This helped to lessen the flickering, but not take it away entirely.


LCD panel loosened and propped up with a piece of styrafoam

IMG_4578.JPG



Opened view of LCD panel (inverter board is unbolted and tipped up for access)

IMG_4583.JPG




Here's the results I came up with by using a digital multimeter. What I find interesting is that the orange inverter wire measured 0v in all states of operation. Perhaps its a ground wire? I'm certain that it must be there for something, but what? MacTester, Kiwi? What do you think?

On the 17" iMac G4, the PWM screen dimming wouldn't work without the orange hooked up to 3.3V. I guess time will tell with this 20" version when I get to testing the PWM dimming control. Thats a ways off yet.



screenshot_152.png




Ersterhernd
 
Build Log 2 -- Setting the Project Goals and Layout

I've got a pretty good idea of what I want this project to look like at the time of completion. That said, there are a few unknowns at this point to which only time will tell the success or not. This is a brief outline of what I hope to accomplish in this mod. There are similarities to my 17" iMac G4 mods in areas that have worked very well previously.


Hardware Summary

- Intel NUC D54250WYK with i5 processor
- 8 GB 1600 DDR3 RAM
- 120 GB mSATA Crucial SSD Storage
- 120 GB SATA3 6.0 Gbps Intel 530
- Apple A1181 Bluetooth
- Broadcom WiFi
- Internal 19V Antec SNP90 Power Brick (90W)
- Internal PicoPSU WI-25-120 PSU
- 12V to 24V Step-Up converter to obtain 24V
- BC547B Transistor actuated PicoPSU on/off control
- Picaxe 08M2 Micro-Controller for touch-sensor LCD brightness control
- Picaxe 08M2 Micro-Controller for pulsing sleep LED
- Picaxe 08M2 Micro-Controller for PWM case fan control
- Startech HDMI to DVI converter with MOLEX PN 74320-4004 connector
- Noctua NF-B9 92mm Case Fan with software PWM speed control
- StarTech ICUSBAUDIO Stereo Audio Adapter
- 3.5mm Audio Jack
- Original iMac G4 speakers
- External 20W amplifier
- Internal Microphone utilization
- 3 x USB 3.0 external port
- 1 x USB 2.0 external port
- Gigabit Ethernet port
- Original Power Plug
- Original Power Button
- Hard Reset button
- Apple BT Trackpad/Wireless Keyboard/Wireless Mouse
- No DVD-ROM will be installed


The Layout

The following diagram illustrates the approximate layout scheme I've chosen to fit all the components into the dome of the G4. Note that the DVD-ROM will not be used, and the resulting space will be re-purposed for other hardware.


iMac20Layout.jpg




It is hoped that this build log in its eventual final form will be of assistance to others embarking on such mods as this iMac G4. Apple created a truly unique design with it that will hopefully be preserved for years to come by modding with current hardware.



Regards,
Ersterhernd
 
Nice build log.

Will you install front USB ports behind the DVD drive door? You could use a Picaxe to allow opening / closing the door with an RC servo... You could use a bigger chip (14M2) and implement the brightness control and the servo control in the same controller. To save precious space, I would do the tests on a breadboard and then solder all the components to a stripboard, like I did it.

I have no idea, what the function of the orange wire could be. Just left it be floating and do some tests.

Good luck and a happy new year!

MacTester
 
Sorry MacTester I mis-stated the number of USB ports. There will be 3 and 1 as edited in the hardware list above. I will be using the strip boards as you did on your HemiMac. There is a local supplier here who sells them and they really are the way to go for space saving.

Yes still scratching my head about the orange wire. Don't have the step up converter here yet so testing is out of the question, unfortunately. It read Zero volts and never moved off of that reading. I don't know how often the inverters in these 20" models fail, hopefully not often. They are a much different part than in the 17" which was relatively easy to access and remove.


Cheers!
 
Why you don't reuse the original PSU in similar way as kiwi will do it in his iMac?

Gruss aus der Schweiz ;)

MacTester
 
MacTester57 said:
Why you don't reuse the original PSU in similar way as kiwi will do it in his iMac?

Gruss aus der Schweiz ;)

MacTester
Click to expand...


Greetings from Canada, EH? ;)

I thought long and hard about the original PSU. The vendor who sold me this machine told me that about 5 years ago it made a "POP" sound one day and he took it to the Apple Store for a PSU replacement. So the one currently installed is probably not as old as most in this vintage of machine. I figured that the odds of that happening again are probably higher with a G4 PSU than with a new 90W Antec brick. If I ever had to rework this project from a G4 PSU into a new model PSU it'd be a major re-think, so why not just use new hardware at the start? 90W should be plenty for what I'm going to do here anyway.

I grabbed a brand new in box Apple Service Part # 922-6129 iMac G4 20" LCD inverter today off eBay. Even if I never use it, the cost of having a spare was minimal. I've read of numerous failures of this part on the forums.


tioo.png




On a side note, wife and I are going to be in Europe this fall. Seeing your beautiful country is one of our goals.


Cheers!
 
I thought long and hard about the original PSU. The vendor who sold me this machine told me that about 5 years ago it made a "POP" sound one day and he took it to the Apple Store for a PSU replacement. So the one currently installed is probably not as old as most in this vintage of machine. I figured that the odds of that happening again are probably higher with a G4 PSU than with a new 90W Antec brick. If I ever had to rework this project from a G4 PSU into a new model PSU it'd be a major re-think, so why not just use new hardware at the start? 90W should be plenty for what I'm going to do here anyway.
Click to expand...

I think, this is a good idea. The disadvantage is, that more space will be needed.

On a side note, wife and I are going to be in Europe this fall. Seeing your beautiful country is one of our goals.
Click to expand...

Just write me a PM, if you come to Switzerland, you are welcome!

MacTester
 
Status
Not open for further replies.
Copyright © 2010 - 2024 tonymacx86 LLC
Back
Top