[Solved]
Read this and the whole thread to see if it's your case.
I bought this iMac 17" with a non working LCD screen. Seller assured me that it worked but needed repair and so decided to sell.
After some research the iMac has indeed a 15" model motherboard and the LCD is a 17" inch model.
The inverter was fine as I could still adjust brightness via OS and it would work, but no image.
With schematics and some help
)) I found the issue.
An inductor went bad and it was not allowing the correct voltage (2V less than needed) to the LCD. Removed it works like a charm.
Bottom line:
1) LCD screen connector is the same for 15 and 17 USB 2.0 model motherboard
2) screens between those models are interchangeable (see motherboard model in thread)
3) you can check voltage without opening up the LCD by probing the pins on the motherboard
4) if you want to check continuity on the LCD cable you have to open the screen and that's not too hard but you'll break pins on the frame and you'll have to glue it back on (I used some double-side tape). It doesn't look silk smooth after, so beware before you do that.
Hope it helps to get some old G4 iMac back in shape.
If anyone knows it was solved before please add link.
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Hello!
I've been trying to repair a 17" Lamp G4, the issue is a grey screen and no image; VGA out works with an ext screen, and if no screen is connected you can actually do things a hear sounds but no image (e.g. playing a cd).
After opening and checking these are the things I discovered:
- the motherboard is actually a 15" USB 2.0 model 1Ghz (https://everymac.com/systems/apple/imac/specs/imac_1.0_15_fp.html)
- lcd is a 17" model (https://everymac.com/systems/apple/imac/specs/imac_1.25_17_fp.html)
At least the inverter isn't damaged. In my notes I have "Rx0-" and "RxC+" no continuity, probably broken lines or different location on mobo connector (being Apple it could be)
I have some dupont cables to connect things and try stuff. Probably extrapolated from dremeljunkie (www (dot) dremeljunkie (dot) com).
So, no wonder it doesn't work.
They guy that sold it to me said he had it working for some time and then the LCD went bad.
I believe he never got it working and had a patchwork attempt sold for a few bucks (40€/50$).
All I need is to find the pinout of the connectors on the motherboards - 15 and 17 inches - and the cable pinout of both LCD connectors.
I have looked around but couldn't find anything, even the precious dremeljunkie helped me but to an extent as I didn't complete the job.
Another user had a similar problem with a 17/20" LCD, but 20" is a whole different thing and doesn't apply here.
Before I go diehard mode on this and start from square 1, if anyone has these pinouts at hand I'd be very happy to have them and try to repair anything if it can be done.
My last notes date back to 2018, I don't remember much of what I did.
Huge thanks in advance for any help, thoughts and even two cents
Read this and the whole thread to see if it's your case.
I bought this iMac 17" with a non working LCD screen. Seller assured me that it worked but needed repair and so decided to sell.
After some research the iMac has indeed a 15" model motherboard and the LCD is a 17" inch model.
The inverter was fine as I could still adjust brightness via OS and it would work, but no image.
With schematics and some help
)) I found the issue.An inductor went bad and it was not allowing the correct voltage (2V less than needed) to the LCD. Removed it works like a charm.
Bottom line:
1) LCD screen connector is the same for 15 and 17 USB 2.0 model motherboard
2) screens between those models are interchangeable (see motherboard model in thread)
3) you can check voltage without opening up the LCD by probing the pins on the motherboard
4) if you want to check continuity on the LCD cable you have to open the screen and that's not too hard but you'll break pins on the frame and you'll have to glue it back on (I used some double-side tape). It doesn't look silk smooth after, so beware before you do that.
Hope it helps to get some old G4 iMac back in shape.
If anyone knows it was solved before please add link.
---------------------------------------------------------------------------------------------------------------------------------------------------
Hello!
I've been trying to repair a 17" Lamp G4, the issue is a grey screen and no image; VGA out works with an ext screen, and if no screen is connected you can actually do things a hear sounds but no image (e.g. playing a cd).
After opening and checking these are the things I discovered:
- the motherboard is actually a 15" USB 2.0 model 1Ghz (https://everymac.com/systems/apple/imac/specs/imac_1.0_15_fp.html)
- lcd is a 17" model (https://everymac.com/systems/apple/imac/specs/imac_1.25_17_fp.html)
At least the inverter isn't damaged. In my notes I have "Rx0-" and "RxC+" no continuity, probably broken lines or different location on mobo connector (being Apple it could be)
I have some dupont cables to connect things and try stuff. Probably extrapolated from dremeljunkie (www (dot) dremeljunkie (dot) com).
So, no wonder it doesn't work.
They guy that sold it to me said he had it working for some time and then the LCD went bad.
I believe he never got it working and had a patchwork attempt sold for a few bucks (40€/50$).
All I need is to find the pinout of the connectors on the motherboards - 15 and 17 inches - and the cable pinout of both LCD connectors.
I have looked around but couldn't find anything, even the precious dremeljunkie helped me but to an extent as I didn't complete the job.
Another user had a similar problem with a 17/20" LCD, but 20" is a whole different thing and doesn't apply here.
Before I go diehard mode on this and start from square 1, if anyone has these pinouts at hand I'd be very happy to have them and try to repair anything if it can be done.
My last notes date back to 2018, I don't remember much of what I did.
Huge thanks in advance for any help, thoughts and even two cents
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