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

[ersterhernd]

Hi Kiwi, thx for your input... read the post directly up from your last. It was a little delayed getting posted. This iMac is appearing very solid at the moment.

Ersterhernd

 

[ersterhernd]

Build Log 16 -- Video Connection

(I'm happy to say that this is my FIRST POST being entered using this iMac 20" build)

The Intel NUC D54250WYK has two video ports on the back, minidisplayport and miniHDMI. I chose to use the miniHDMI for a couple of reasons, one of which is I've had success with HDMI to DVI to TMDS conversion in my two previous iMac G4 projects. Success just can't be argued with.

This iMac 20" would require four parts to order for the conversion as pictured.

1. MiniHDMI to HDMI converter
2. Male/Male HDMI cable
3. Female/Male HDMI to DVI converter
4. Molex part number 74320-4004 for TMDS conversion



MiniHDMI to HDMI converter plugged into NUC and mounted firmly to AC Filter with heavy velcro. Great care was taken to mount this in such a way that no stress is placed on the NUC HDMI port.

The Male/Male HDMI cable is a very heavy guage to eliminate interference. It fits perfectly into the upper DVD mount, out of the way of other hardware. The HDMI cannot be plugged in until the iMac G4 base is installed. I use a temporary HDMI F/F coupler and extra M/M cable to operate the iMac with the base off. The cable stays mounted permanently as shown. It provides a perfectly sized fitment into the dome to allow the base to be connected.

The HDMI to DVI converter with TMDS conversion wiring into the Molex part. Note that this wiring was later re-worked, grounded and shielded due to interference noise issues on the LCD in OSX.

The completed connection with labeled particulars.

Note, there was considerable effort required to cleanly install the iMac wiring. Proper grounds, shields and Ferrite rings on supply lines were necessary to achieve a quality video signal on the 20" screen. This was definitely the most challenging portion of the build so far. A gamma setting of 1.8 in OSX was required for solid operation.


Ersterhernd

 

[ersterhernd]

Build Log 17 -- iMac G4 Base to Dome Wiring

The following wires were tied into on umbilical-type routing from the base up into the dome. All base wires enter the dome in one open corner so there is no restriction upon re-assembly. Inside the dome, the excess wiring is hidden securely zip-tied in the lower DVD bracket rail.

1. USB 2.0 wiring from NUC header for External Audio and Apple A1181 Bluetooth
2. 5V wire from Pin 9 of NUC front panel header for PicoPSU switch-on and LED detection
3. Power switch wires (2)
4. Reset button wires (2)
5. Internal Mic wiring (2)
6. Apple Bluetooth 3.3V supply wire
7. Auxilliary 5V and GND wires for later use. (internal amplifier?)
8. AC wiring
9. AC Earth wire for faraday cage ground
10. Intel NUC 19V power cable
11. Original iMac G4 WiFi antenna wires (2)


Ready to assemble the iMac G4 Base to the Dome.

Ersterhernd

 

[ersterhernd]

Build Log 18 -- Final Assembly and Presentation

Its Done! The iMac G4 20" is assembled and ready for it's first showing. Testing and tweaking will follow. These photos are the final product as will be in use going forward.

Ersterhernd

 

[kiwisincebirth]

You sound confident that problem solved one and for all. (fingers crossed). I have a couple of questions.

What is the model number of the 20" panel ?

How did your conversion of original WIFI antennas work out ?

Kiwi

 

[ersterhernd]

You sound confident that problem solved one and for all. (fingers crossed). I have a couple of questions.

What is the model number of the 20" panel ?

How did your conversion of original WIFI antennas work out ?

Kiwi

I've had this thing running video and a bunch of other windows for several hours now, Kiwi. Not a single misbehaved pixel. TOUCH WOOD.

The LCD panel datasheet is attached.

The WiFi antennas will push data through up to the max that the G-Series router I have in the kitchen will do. Internet downloads over 2MB/sec. Haven't tried an N series connection yet. I'd say the soldering was a success.

Very happy to have found the gamma solution, I was at my wits end with this thing.


Cheers!

 

[ersterhernd]

Build Log 19 -- Project Summary


This was without a doubt the most difficult mod I've completed to date. It far surpassed the efforts required in the completion of the iMac 17" models that I did last year. The larger screen in this model turned out to cause much more of a challenge than I had originally thought. I got literally broadsided by an unexpected surprise when I booted the Intel Haswell NUC on it the first time (halfway through the project). The iMac LCD was riddled with graphical corruption, red pixels (thousands of them) flickering rapidly in a controlled pattern. See this post for the gory details of that. At the present time, the issue appears to be resolved, but only time will tell that for sure. I've had 'head-scratchers' before with these projects, but nothing quite like this issue. It took three major modifications to the system wiring and a lucky discovery about gamma correction to find the fix.

The machine is gorgeous and pleasure to use in these first hours of enjoyment. It is TOTALLY silent. The screen brightness is adjustable by touch control and very bright when turned up. WiFi and Ethernet are fast and packet-loss free. The two SSD drives in the system are effective for primary and backup. Apple A1181 bluetooth is silky smooth with the Apple Magic Trackpad.

The D54250WYK NUC isn't cheap, but feature-rich and accepts OSX Mavericks like a champ. The only unusable part of it is the infrared, because of the iMac built around the NUC there is no practical application for it.


Final Hardware Summary

- Intel NUC D54250WYK with i5 processor @ 1.3 GHz
- Speed Stepping currently functional up to 2.3 GHz
- Sleep and Rewake fully operational
- 8 GB 1600 DDR3 RAM
- 120 GB SATA3 6.0 Gbps Intel 530 (boot)
- 128 GB mSATA Crucial SSD Storage (backup)
- Apple A1181 Bluetooth
- Broadcom N Series 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 via 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 was installed


Conclusion

The key ingredient in this project was persistence. Without it, failure would have been imminent. Special thanks to both Kiwi and MacTester for their continuous support and advice that helped me get through to the end result.

It has been a pleasure to document this thread and build log, I hope those that have taken the time to read it have found it informative. It would be rewarding if the content will be of assistance to other modders in their projects.


EDIT : After further testing and subsequent LCD graphic corruption, I was forced to make a significant change in the build to achieve full stability. Read about it at this link.

EDIT : The revised final hardware summary is at this link.


Cheers!

Ersterhernd

 

[ersterhernd]

Did a quick GeekBench test. Here's the result. Used GeekBench 2 64 bit.

Ersterhernd

 

[kiwisincebirth]

I've had this thing running video and a bunch of other windows for several hours now, Kiwi. Not a single misbehaved pixel. TOUCH WOOD.

The LCD panel datasheet is attached.

Very happy to have found the gamma solution, I was at my wits end with this thing.

Interesting. The ID Tech data sheet you sent is Exactly the same as the one I tracked down for the iMac 20" G5, although not sure I may have an LG panel. Will be interesting to if I have same issue with Gamma, probably, since same NUC, and OS will be driving the panel.

 

[leopoldporkstacker]

Damn that’s a quite involved hack project. Well done!!!