Ersterhernds iMac G5 (iSight 20 A1145) Project

Discussion in 'iMac Mods' started by ersterhernd, Mar 23, 2014.

  1. ersterhernd

    ersterhernd

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    Mar 23, 2014 at 9:39 PM #1
    ersterhernd

    ersterhernd

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    Hello Everyone,

    I'm currently in a 6-week recovery from minor abdominal surgery, so in my off-time decided to embark upon yet another iMac mod to fill in my time of physical immobility.

    This project is an A1145 20" 2.1GHz G5 iSight model that I acquired off Craigslist in working condition for only 30 dollars. It was first intended to be used only as an LCD replacement for my 20" iMac G4, in case the LCD panel ever failed in that machine. There isn't a single mark on the LCD, and the pixels are perfect, not a bad deal for only thirty bucks.

    The system itself (with exception of the LCD) was pretty beat up. Scratches, stickers, spots of glue and paint splashes were all over the exterior; the original white keyboard was even worse. It had been used since brand new in a local art studio, but was being sold off because it was continually shutting itself down. I'm assuming the issue was heat related, because the iMac was jam packed with dust clumps when I disassembled it. A quick visit to my air compressor in the garage fixed that in a hurry.

    I finished a 17" G5 mod only a few weeks ago. It is linked here. This build will include much of the same feature set as that one, with the exception of a larger LCD display and the power requirements it imposes. I've already ordered the many parts that are required, the system will be based on the same Intel NUC DC3217BY as the previous one. These are dirt cheap now, I offered 150.00 dollars on a brand new retail boxed version on eBay and the vendor sold it to me. I simply cannot believe the way the prices have come down on this apparently unloved non-ethernet version of the i3 NUC.

    I will detail a complete build log as with my other projects. I'm part way into the work already so will also outline my progress to date. My rationale will be explained and open to comments as always. There are a couple of hurdles to jump over with this project, but I'm hopeful to find success at the end. As usual, like with any mod, there's no guarantee and with this model there's no instruction manual to follow. I've not seen a completed A1145 project done anywhere so far.

    Hope you enjoy it. I hope I do too!


    Cheers!

    Ersterhernd
     
  2. ersterhernd

    ersterhernd

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    Mar 23, 2014 at 9:59 PM #2
    ersterhernd

    ersterhernd

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    Build Log 1 -- Cleaning Up the iMac

    I unfortunately did not photograph this machine when I got it home. Take my word for it, the thing looked awful. The white polycarbonate shell was in about 3/10 condition. The system would shut down after 15 minutes of use, as I stated in my first post I'm assuming due to heat.

    Fortunately, the surface of the machine looked as though with some elbow grease that it might be restorable to a better appearance. The thousands of scratches were very light, not deep gouges in the surface. The glue and stickers and paint spots all over it looked to be removable. I figured it was at very least worth a decent try.

    Here's the products I used, a Maguires ScratchX and a micro-fibre cloth.


    [​IMG]



    This was the result after about 3 hours (including a shower for me!); a nearly perfect iMac 20" iSight model. I had to go pretty easy because of my new abdominal incision, but I'd give it at least a 9 out of 10 now after the time and effort it took. The liner in the top slot (rear view) is a little yellowed, but I think I can clean that up, too.


    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]


    Now with a outwardly presentable system to work with, I could call this project a 'Go'. :thumbup:



    Ersterhernd
     
  3. justein230

    justein230

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    Mar 23, 2014 at 10:42 PM #3
    justein230

    justein230

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    Before you started this one I thought you had a collection to brag about... Now you just keep adding! I wish I had the expertise to do these, as I am eager to learn and it is amazing to say that you have achieved something as tedious (and awesome) as this. Good luck with this one!
     
  4. ersterhernd

    ersterhernd

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    Mar 23, 2014 at 10:44 PM #4
    ersterhernd

    ersterhernd

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    Build Log 2 - Project Challenges

    There were 2 hurdles that I could see initially with rebuilding an A1145 model. Both were related to the LCD display. Apple created this machine much differently than its predecessors, both 17" and 20". In those models, there was a separate inverter with a specific Apple Part Number to control the LCD brightness via a set of backlights built into the LCD itself. In this A1145 version, the inverter does not exist as a separate distinctive part, but rather is built into a combined inverter/DC/DC converter part that connects to the G5 Power Supply via a proprietary connector cable.

    ---------
    EDIT: Eight months after this project was completed, I discovered a solution which could utilize the original iMac PSU and Inverter. See this post... http://www.tonymacx86.com/imac-mods/150793-imac-isight-model-power-supply-unleashed.html

    If I attempt another iSight mod, it will use the above method.
    ---------


    The Problem

    1. There was no obvious method of controlling the backlights for the screen brightness.
    2. The original iMac G5 PSU must be used. A replacment configuration wouldn't likely work.


    The iMac A1145 inverter/DC/DC converter

    [​IMG]


    The stripped down iMac G5 with the inverter/DC/DC converter shown connected to the iMac PSU in the upper left of the system. Both Apple parts highlighted in green work as one piece in this iMac G5.

    [​IMG]


    As shown above, there is NO inverter cable that connected to the Logic Board in the A1145 iMac. The LCD backlights plug into four connectors on the black inverter, which is hardwired directly into the DC/DC converter, forming a single part.

    Controlling the backlights with either software or hardware would be difficult at best, and any hope of using a more up-to-date Power Supply was seemingly impossible in this configuration. What was even worse, the existing PSU in this particular iMac had badly bulging and leaking capacitors already, a sign of imminent failure.

    There simply had to be another way. :think:


    The Proposed Solution

    To complete this build the way I really wanted to, I needed to find a way of powering and controlling the LCD backlights while using an aftermarket PSU of my choice. It would need to be around 90W as I estimated the combined draw of the system and LCD screen would lbe approximately 60W in normal operation, even higher under load. Some form of separate LCD inverter and PSU would need to be used for this to ever work under a custom configuration. The components would have to be sized so they fit into the minimal amount of depth space available behind the 20" LCD panel.

    After some research, here's what I discovered. The 20" LCD panel in this G5 was very similar to that of the previous generation iMac G4 20" model. For comparison I used these two links...

    iMac G5 Panel - LG Phillips LM201W01-(ST)(B2) vs. the iMac G4 Panel - IDTech M201Z2-M01

    I was especially interested to see that the power requirements and pinouts for the inverter connection on both panels was nearly identical. This was significant because in the previous generation iMac G4 20", the inverter was a separate part that I could connect to. In fact, I'd already done it successfully in my iMac G4 20 inch build that was completed earlier this year. Fully functional screen dimming was part of that project, as detailed in this link. The G4 inverter is only about 7mm thick so could likely be squeezed into the confined space under the G5 LCD. Being a separate Apple Part, it uses its own inverter cable (runs through the iMac G4 neck) which could be connected to some form of 24V power and adjustable brightness, too. I figured it was worth a try.

    I lucked out and found a "brand new in box" inverter from a 20" iMac G4 off of eBay. Apple Part Number 922-6129. It was designed specifically by Apple for the G4 20" LCD, an IDTech M201Z2-M01.

    [​IMG]



    Here's what it looks like temporarily mounted onto the back of the LM201W01-STB2 panel in this G5. The great news is, the LCD fits perfectly into the case with the inverter installed. All that remains is the test run to see if the inverter will work with this panel; the pinouts are identlcal to the IDTech panel in the G4, so my fingers are crossed that it will all work fine. I have also ordered a replacement neck from a 20" iMac G4 to remove the inverter cable that connects up to this inverter. My plan is to also (later on) use the LCD wires for connection to the 30-pin TMDS on this G5 display.


    [​IMG]

    [​IMG]



    The G4 Inverter will fit into the thin position as shown. In a test fit of the LCD, the system closed up perfectly with the new 100W power supply installed.

    [​IMG]




    Time will tell if this works or not. I'm still waiting for the iMac G4 20" neck (with inverter cable) so I can properly connect power to the inverter via the native cable and test functionality with this G5 LCD.



    Ersterhernd
     
    Last edited: Dec 21, 2014
  5. ersterhernd

    ersterhernd

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    Mar 24, 2014 at 5:23 AM #5
    ersterhernd

    ersterhernd

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    Build Log 3 — Hardware Goals

    This is a brief outline of what my iMac G5 should look like at the end of the project. It is fairly similar to my previous 17" G5 build.


    The proposed hardware list is as follows...

    - Intel NUC DC3217BY with i3 processor
    - 8 GB 1333 DDR3 RAM
    - 128 GB mSATA Plextor SSD Storage
    - Apple A1181 Bluetooth
    - Broadcom ’N’ Series WiFi
    - Powerstream PST-YD-100W Notebook Power Adapter (internally mounted)
    - Internal PicoPSU WI-25-120 PSU
    - 12V to 24V 3A 72W DC/DC Upconverter
    - Apple iMac G4 20" inverter PN 922-6129
    - Apple iMac G4 20" Neck (for extraction of LCD and Inverter Cables only)
    - 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
    - Startech HDMI to DVI converter with MOLEX PN 74320-4004 connector
    - ISD1820 audio recorder with Apple iMac G4 Speaker (Mac Startup Chime)
    - NZXT IU01 internal USB Hub
    - Original iMac G5 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
     
  6. ersterhernd

    ersterhernd

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    Mar 24, 2014 at 11:36 AM #6
    ersterhernd

    ersterhernd

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    Build Log 4 -- iMac G5 Hardware

    The only internal parts remaining and used from the iMac G5 are:

    1. Speakers
    2. AC Filter & Pigtail connector wire
    3. LCD
    4. Rear I/O section of Logic Board (cut out)
    5. WiFi Antennas
    6. IR Receiver
    7. CPU Fan & Intake Fan
    8. Native power button on rear


    Photo of the stripped down G5 with the remaining usable original parts (note: PSU is aftermarket).

    [​IMG]


    The bottom right corner of the original G5 Logic Board retained for rear USB ports and system LED

    [​IMG]

    [​IMG]


    Wires soldered to USB trace pins on the Logic Board

    [​IMG]


    Demonstration of the original LED

    [​IMG]


    As is shown here, not much is actually re-used from the long list of old Apple G5 parts. Definitely however, whatever can be used is used.


    Ersterhernd
     
  7. ersterhernd

    ersterhernd

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    Mar 24, 2014 at 11:45 AM #7
    ersterhernd

    ersterhernd

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    Build Log 5 -- Hardware Layout Map

    Careful planning of the hardware layout is critical in any iMac build, because of the confined working space and depth restrictions. I prepared this layout map of all existing and planned hardware to show exactly what parts are going to fit in pre-determined locations. I have test-fit the LCD panel and successfully closed the system up with re-installed front bezel using this configuration.

    There is one minor mistake in the diagram, it should say 'iMac G4 Speaker' not 'G4 Cube Speaker'. :oops:


    [​IMG]



    Ersterhernd
     
  8. ersterhernd

    ersterhernd

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    Mar 24, 2014 at 12:10 PM #8
    ersterhernd

    ersterhernd

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    Build Log 6 -- Internal Power Supplies

    The project will implement use of the original power cord into the rear of the iMac, connected to two internal power supplies. One to provide conversion from AC to 19V DC for the Intel NUC and PicoPSU, and the PicoPSU itself is the Wide Input WI-25-120 version that can easily handle that 19V supply. It will provide all components in the system (with the exception of the Intel NUC) the required 3.3V, 5V, 12V and Grounds.

    This iMac will be require approximately 60W at idle, I am estimating, depending on the screen brightness setting. To leave some headroom for this requirement, I decided to go with a 100W notebook PSU to supply 19V. It is a PST-YD-100W from PowerStream Technology, A division of Lund Instrument Engineering, Inc. in Utah, USA. It has variable voltage output from 12V to 24V that is set by a switch on the bottom of the PSU. It also sports a 5V USB output as well, which may come in handy for standby power if I ever need it. This PSU is in an 'always on' state, plugged into AC power.


    The PowerStream PST-YD-100W with the variable switch set to 18V. I have placed 2 sticky pads in position to ensure the switch cannot be inadvertently clicked to a different setting.

    [​IMG]


    The PicoPSU WI-25-120 mounted firmly into position. I have carefully wrapped it with electrical tape to prevent shorting contact with the iMac metal frame. This PSU will turn on and off with the Intel NUC when the power button on the rear of the iMac is pressed.

    [​IMG]

    [​IMG]



    Ersterhernd
     
  9. ersterhernd

    ersterhernd

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    Mar 24, 2014 at 1:08 PM #9
    ersterhernd

    ersterhernd

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    Build Log 7 -- iMac LED Functionality

    One of the sweet features of the white iMacs was the crisp circle LED that appeared on the polycarbonate front face of the machine when power was turned on. This little glowing circle would also pulse on and off in a 'breathing' style rhythm during sleep. MacTester57 created a way to perfectly emulate this functionality in his G4 HemiMac build, and I've implemented it successfully into all my iMacs so far. This build would be no different.

    To accomplish this, a Picaxe 08M2 micro-controller chip is used to control the voltage to the LED via Pulse Width Modulation (PWM). Its not as complicated as it may sound; essentially about a kilobyte of software code is written and stored on the Picaxe chip, which runs continuously when the iMac is powered up. The Picaxe is mounted into a stripboard that contains the required circuit to operate the iMac LED. Details of that are already documented at this link.

    The iMac LED is very bright, so the proper EMI shielding needs to be re-applied to the inside of the front bezel to properly contain the light into a crisp white circle.

    [​IMG]



    The Picaxe 08M2 installed into the stripboard circuit. This is a perfect place to mount the Apple IR Receiver and Bluetooth Antenna, as it sits directly behind the little gray 'Apple' logo on the front bezel. The board itself is mounted with a 3M sticky pad to the AC filter. It is rock solid there. The Apple A1181 Bluetooth module is mounted to the rear of the stripboard, and the short 3" antenna wraps around the front for clear bluetooth reception.

    [​IMG]


    The LED controller board wired into the iMac (lower center of the photo).

    [​IMG]


    I hacked off the bottom right corner of a junk 17" iMac G5 so I didn't have to mount the full front bezel every time I wanted to test the LED brightness. It was a simple but effective solution to view the desired effect of the filtered LED through the white polycarbonate.

    [​IMG]

    [​IMG]




    Ersterhernd
     
  10. kiwisincebirth

    kiwisincebirth

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    Mar 28, 2014 at 3:09 AM #10
    kiwisincebirth

    kiwisincebirth

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    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
     

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