Ersterhernds iMac G5 (iSight 20 A1145) Project

[ersterhernd]

This is astounding work so far, can’t believe how quickly you move from one project to another. Looks like this machine was a big re-design from the one I am doing. Very different challenges.

Some feedback:

PSU / Inverter
The combined inverter-DC power supply must have a way of being controller by software, looking at your picture of the board it looks like there are three cables, one of which (I assume) is connected to the main logic board. my guess would be that one of the pins in this cable provides the PWM signal from the logic board to the inverter.

To reuse the PSU, would need to just map out the PINS on the cable that links to the logic board, find the appropriate power and control signals.

As for re-using an old PSU, in my project I have measured the wattage on wall socket and at peak usage, is less than half the rated capacity of the PSU. While not nothing this will put less strain on PSU, and help prolong its life. Cant speak to issues

As for your solution, should work perfectly.

Front Panel LED
You note that the LED is very bright, I would consider putting a resistor of a higher value in series with the LED to limit the current, reduce the brightness, and extend the life of the LED.

Kiwi

Hello Kiwi, your points are very good. You're idea that one of the wires in the Logic Board connector carrying the PWM signal is probably right. The inverter has to be controlled somehow, this is probably it. I applaud your re-use of the original PSU, I'm assuming yours is in much better condition than this one was... it looked close to death.

I've already added a resistor to the line. Be careful with the iMac LED. Dont go any higher than a 3.3V supply with it. I was playing around with a 17" G5 junker here and toasted the LED with 3xAA size batteries (around 4.2V measured output). It flashed 3 times, dimmer each time and went dark. I didn't need it anyway, was just testing it out. Careful with yours...

I hope you're right about my proposed solution actually working. Going to test it tomorrow. The 20" iMac neck arrived today.



Cheers!

 

[ersterhernd]

Progress update...

Had a busy couple of days on this iMac. Most of the circuits are in place now. Just the LCD, Audio Amp and 24V upconverter to wire in now. Unfortunately I'm waiting for the 24V upconverter from China. I've got an iMac G4 PSU (24V) here so i can do my LCD testing with that for now.

Installed in last two days: NZXT USB Hub, Apple Chime, Intel NUC DC3217BY, Brightness Slider, All USB and PicoPSU powered circuits (just loose wires now ready for connecting). I've followed my layout map (see post # 7) closely and I test-fitted the LCD tonight. It lays in the iMac perfectly. The screen is exactly flush with the surrounding cabinet.



Items that still need to be done... LCD, Audio Amp, Upconverter


Ersterhernd

 

[ersterhernd]

Build Log 8 - Video Installation (Part 1)

One of and if not the most challenging parts of any iMac build is getting the LCD wired to the newly installed hardware. This build posed an extra hurdle in that there was no inverter cable in the original iMac G5, but rather a hardwired solution that was virtually unusable in a mod. That issue and potential workaround is detailed in this post that I made last week. My solution involved the use of an iMac G4 20" LCD/Inverter cable and the actual G4 inverter itself. Whether it would work or not with the LCD from this G5 remained an unknown, but worth the gamble. If worse came to worse, I could likely find a 20" G4 LCD somewhere if I had to.


Preparing the Video Cables


First I had to order a 20" G4 neck off of eBay, with shipping was 30 dollars and a typical 2-week wait to Canada. I already had a brand new G4 20" inverter here, so was good to go with that.


The iMac G4 Neck, complete with LCD and Inverter cables

Using four small jewellers screwdrivers (2 in each side of the neck), I removed the two neck pivot nuts. Placing the neck in the vise to hold it really helped with this.

The neck with the pivot nuts and shafts removed

Using a flathead screwdriver I then pryed the neck apart

I removed all the screws (T6 and T8 Torx) and snap-rings from the neck. A couple of snap-rings are really small, so I dremeled them off.

Once that was done, the other half of the neck slid off easilty, revealing the pivots at each end

With a bit of wiggling and persuasion, the pivots came out of their rotational sockets. Care must be exercised so as not to damage the cables by pinching them

Next, the white plastic protective tubes must be snapped off each of the cables

Next, the cable-end connectors (Logic Board end) must be carefully removed from the tiny pins. This applies for all the cables, as they will each need to be threaded back through the neck, and will not fit with the logic board connectors attached. A safety pin works great for the removal of the plastic ends.

The tiny plastic tabs are bent upward (using the safety pin) and the pins are ready for removal

LCD cables (Black and Gray) with free wires and pins. Note that the shielding mesh is left connecting the 2 cables togther, they are not separated. This mesh is later soldered via heavy ground wire to the DVI GND pin to properly ground the shield and help eliminate EMI interference on the cables.

The end result, the Inverter Cable (left) and LCD Cables (right) ready for installation. Note that the combination Microphone/LED cable can be cut off and tossed away, it is not required.

Part 2 is next.


Ersterhernd

 

[ersterhernd]

Build Log 9 - Video Installation (Part 2)

Part 2 of the Video Installation will detail the LCD and Inverter Wiring for the LG-Phillips LM201W01-STB2 panel found in the 20" iMac G5 iSight.


Parts Required

1. MOLEX PN 74320-4004 from Digikey.ca
2. Startech HDMIDVIFM adapter from Amazon.ca
3. 1K Ohm resistor (0.5W)
4. EMI shielding foil from the iMac G5 front bezel
5. LCD Cables and Inverter Cable from iMac G4 20"
6. iMac G4 20" Inverter part number 922-6129


The Pinouts


- Inverter Pinout -

- LCD Pinout -

To Complete the DVI connection as noted in the above Chart, I used this method of soldering the 1KOhm resistor directly to the DVI pins 14 and 16. I used an extra iMac G4 wire for pin 15, although it would have been just as effective to solder a small wire directly to the pin, so no additional pinned wire would be required. I did this work prior to connecting any of the other pins. To obtain a VEDID signal, I soldered TMDS 15 (hot pink wire) directly to 3.3V from the PicoPSU.

This turned out to be a simpler solution than rewiring the Vedid/Hot Plug Detect loop into the TMDS.

This is the completed work. Unfortunately DVI pin 1 (bottom left of the photo) needed to be soldered because the iMac pin got damaged somehow, as these tiny pins are very fragile. The heavy black wire on the right is a bridge between the DVI ground (as shown below) and the iMac LCD Cable shield (shown in second photo).

Final product after wrapping the assembly in EMI shielding foil (taken from the G5) and connecting it to an 18" HDMI cable (plugged into the Intel NUC). The height (depth) still allows sufficient clearance to fit the LCD panel on top of it all.

Connected to the assembly are 5 wires -

1. Black LCD cable
2. Gray LCD cable
3. Black GND wire
4. Yellow 12V wire
5. Orange 3.3V (VEDID) wire

HDMI cable plugged into the Intel NUC

Ersterhernd

 

[ersterhernd]

Build Log 10 - WiFi Hookup

The iMac G5 iSight came with a wonderful set of antenna wires already done for me. A simple installation of the Broadcom N Series mini-PCIe card into the NUC and plugging the antennas in was all there was to this portion of the build.



Ersterhernd

 

[ersterhernd]

Build Log 11 - First Power-Up

In these case mod builds, the moment of truth really arrives at the first press of the power button. I'm still waiting for my 12V to 24V upconverter to arrive, but I have a larger-sized spare one here that I could use in a test. I connected it up to the iMac and inverter, double-checked all my circuits, crossed my fingers, held my breath and pushed the power button.

All I got was brief (fraction of a second) blip, the fans tweaked slightly, then the PicoPSU shut itself off. The Intel NUC, however, was still running, I could hear the fan.

I tried it again... same thing. The PicoPSU was detecting some kind of amperage overdraw and immediately powering down, leaving only the NUC running.

I disconnected the LCD and inverter, leaving the 12V to 24V upconverter connected... Same result.

I unplugged the 12V supply to the two iMac fans... same result.

It turns out that the PicoPSU just plain DOESN'T LIKE this spare 24V upconverter that I've got for testing. I certainly hope that changes with the one that is on its way here, as I didn't have this issue at all with my G4 20" iMac with the same design. If not, a significant redesign will be required to get this LCD powered up correctly. Any thoughts on this issue are welcomed...

Temporary solution - I wired the problematic 24V upconverter to a separate ATX power supply and ran it from there. It didn't have any trouble whatsover in powering the inverter and backlights on the LCD.

That one issue put aside, here's the result I got when I connected the entire system together using the extra power supply to test the iMac for the very first time...

My solution of the iMac G4 20" inverter and all cabling looks like it worked!

I successfully flashed the BIOS in the Intel NUC to a newer version. I let the machine run in this state for a couple of hours, navigating through the BIOS continuously in my first test of this configuration.

Very happy so far! l'm hoping that good fortune stays on my side.



Ersterhernd

 

[ersterhernd]

Build Log 12 - OSX Mavericks Installation and Testing

The machine ran great with the BIOS screen up. That environment operated without issue, but how would this system configuration (especially the LCD) react to OSX? It was now the perfect time to find that out.

The install itself went without a hitch. Unibeast installer, DSDT in place on the USB stick and all worked smooth. Booted straight away to the OSX 10.9.1 installer screen. Upon completion I patched the AICPUM kext with Multibeast, wrote the Chameleon bootloader to the boot drive and restarted. Everything worked.

Backing up the install with SuperDuper

After the install, an immediate update to 10.9.2

So far after testing, all the hardware works including webcam, audio, mic, bluetooth, infrared and Apple Startup Chime. WiFi performance through the iMac original antenna wires is very fast. The LCD performance has been solid in intial test runs, without any corruption or artifacting whatsoever. Sleep works, too, as does LCD brightness control with the installed Grove Slide Potentiometer.

Thats enough for one day. I'm glad that it's come this far with only one issue (the upconverter/PicoPSU conflict) to be resolved at this point in time.



This is always a welcome photo when constructing an iMac build...

Ersterhernd

 

[justein230]

Build Log 12 - OSX Mavericks Installation and Testing

The machine ran great with the BIOS screen up. That environment operated without issue, but how would this system configuration (especially the LCD) react to OSX? It was now the perfect time to find that out.

The install itself went without a hitch. Unibeast installer, DSDT in place on the USB stick and all worked smooth. Booted straight away to the OSX 10.9.1 installer screen. Upon completion I patched the AICPUM kext with Multibeast, wrote the Chameleon bootloader to the boot drive and restarted. Everything worked.

Backing up the install with SuperDuper

After the install, an immediate update to 10.9.2

So far after testing, all the hardware works including webcam, audio, mic, bluetooth, infrared. The LCD performance has been solid in intial test runs, without any corruption or artifacting whatsoever. Sleep works, too.

Thats enough for one day. I'm glad that it's come this far with only one issue (the upconverter/PicoPSU conflict) to be resolved at this point in time.



This is always a welcome photo when constructing an iMac build...

Ersterhernd

Incredible job! I don't know how you can complete all these mods so quickly, but it's really amazing! I love all these old iMac computers that Apple made, even if I've never actually owned one except the iMac G4. Good luck with the upconverter.

 

[ersterhernd]

Incredible job! I don't know how you can complete all these mods so quickly, but it's really amazing! I love all these old iMac computers that Apple made, even if I've never actually owned one except the iMac G4.

Hi J, believe me when recovering from surgery, one has nothing but time on his hands! That aside, I have an affinity for the old iMacs too. G4 or G5 doesn't matter. Looking fwd to seeing your project begin at some point in the near future...


Cheers!

 

[justein230]

Hi J, believe me when recovering from surgery, one has nothing but time on his hands! That aside, I have an affinity for the old iMacs too. G4 or G5 doesn't matter. Looking fwd to seeing your project begin at some point in the near future...


Cheers!

I'm a little scared to begin my G4, as I've never used a dremmel, soldered anything, or worked on anything near similar to this. That said, I really want to learn, so that I can have this iMac G4 modded and brag about it.