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

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Thanks Eesterherd. The black screen I found to be a display issue with the G4. Drove me nuts cause it worked perfectly at first, then when I decide its a go to shrink wrap everything, tape and close up the HDMI connector, and connect again no picture. At first I suspects wiring. Backlight was always working. I tore all connections, measure voltages, impedance, rebuilt, and nothing. I had a spare beat up iMac isight G5. Took that screen connected and bang working. The only thing different is the G4 screen has this ribbon cable coming from controller to the side of the panel. The G5 screen doesn't. Also when I shut down it goes to this loop of colors before shutting down. Have you seen this before? Did not do this with the G4 screen when it worked. I'm going to take it apart and have a look at the controller board, maybe its some connector. Otherwise replace the screen.


Fantastic... Yes I too have a 24" white. I'm thinking replacing that screen with an LED one.


Yes some iSight G5 LCD's do that annoying color loop when going to sleep or powering off. Too bad about your G4 Panel. I hope you can resolve the issue successfully.

Cheers
 
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Yes some iSight G5 LCD's do that annoying color loop when going to sleep or powering off. Too bad about your G4 Panel. I hope you can resolve the issue successfully.

Do you know if the A1076 model screen does the same thing? I may be able to pick one up on the cheap. Everything looked good on that G4 panel. I did notice a difference on the lamps intensity between the G5 and G4. I'm not sure if the G4 light is better contained. G5 panel putting out more light. Maybe the lamps went bad on G4.
 
Joined
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Do you know if the A1076 model screen does the same thing? I may be able to pick one up on the cheap. Everything looked good on that G4 panel. I did notice a difference on the lamps intensity between the G5 and G4. I'm not sure if the G4 light is better contained. G5 panel putting out more light. Maybe the lamps went bad on G4.

No, the A1076 panel behaves itself and shuts down like it should.
 
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Well an A1076 panel also had the color loop, had to find an IDTech one which resulted in normal operation. Too bad the existing panel is in pristine condition. i wish I knew how to troubleshoot the driver board.

Ethernet and Power Switch Wiring

i'm going to attempt to use the existing USB and ethernet port. On the ethernet solder points any good diagram on which color cable goes to what point?
 
Joined
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MSI Z77MA-G45
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i'm going to attempt to use the existing USB and ethernet port. On the ethernet solder points any good diagram on which color cable goes to what point?

I could not get any continuity from the ethernet port to the solder points on the backside of the logic board. Theres some form of powered switch in the port that 'turns it on' when the iMac starts. Thus I could not get it to work. Also be careful as the LED power function runs through the ethernet circuit somehow. Its possible to screw the LED onboard the logic board by hacking at the Ethernet port. Careful.

The USB's Ground and 5V solder points are somehow commonly connected within the logic board somehow. I tried cutting traces really deep with the dremel and still the common ground and 5V power remained. Ended up having to cut out and replace. Its more work, but try as I might, I couldn't successfully separate the onboard ports from each other.


Ersterhernd
 
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I could not get any continuity from the ethernet port to the solder points on the backside of the logic board. Theres some form of powered switch in the port that 'turns it on' when the iMac starts. Thus I could not get it to work. Also be careful as the LED power function runs through the ethernet circuit somehow. Its possible to screw the LED onboard the logic board by hacking at the Ethernet port. Careful.

The USB's Ground and 5V solder points are somehow commonly connected within the logic board somehow. I tried cutting traces really deep with the dremel and still the common ground and 5V power remained. Ended up having to cut out and replace. Its more work, but try as I might, I couldn't successfully separate the onboard ports from each other

No way, really? Just when I thought I nailed the solder points. Never once I thought about testing it. I figured since some builds actually do reuse the ports, just wire them up carefully, then connect to a MB header and test. So u replaced all USB, and Ethernet jack? I didn't catch that on ur build. Infact build log 13 you mentioned successful wired Ethernet. Do all wire lines in Ethernet and USB need to be isolated?
 
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Build Log 4 - AC Power Loop

This build will use the original Apple iMac G4 power cord and AC input. The AC Filter inside the dome will be retained as well. Gone is the original G4 190W PSU, replaced by a 19V 90W Antec SNP90 power brick and PicoPSU WI-25-120 power supply. These pics show both the input and output flow of the power to the iMac.




Power Loop Diagram

89zu.jpg

Good afternoon Ersterhernd,

I dug this project out of my closet and was wondering if, by chance, you'd be able to provide the above Power Loop Diagram that seems to be lost in the death of ImageShack. Thanks so much!
 
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