Can the LM171W02 display be repaired?
Has anyone identified what the missing vertical line defect is in these panels?
Has anyone successfully repaired this display? If so what is required to fix it?
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I believe I know exactly what your problem is. If you can take a screen shot of the problem using your Grab utility, move it around in the background to see if the lines exist on the shot. Or use an external monitor and see if the lines are gone. To be sure take a photo of the problem and post it. If it's what I think, you may be able to get Apple to replace the screen for free. They've done three for me this summer but we've also had reports of them not honoring this, so a silver tongue helps. After I see your screen, and it's what I believe it to be, I'll give you case numbers and "in house" article number. Does your machine have a 1.83 GHz processor?
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Hi,
I think the vertical lines come from defective COF (chip on flex) connection. This chip drives the current for the pixel on the panel and interface with the driver chip (LVDS chip). On this screen there is 4 horizontal COF, and 5 vertical COF.
Repairing this will need in my opinion high skills, good tools like hot bar soldering station (the chip is not soldered but glued thanks to an anisotropic tape) and good knowledge. I don't think this can be done by a DIY. By the way, the replacement of the whole screen seems to be the best solution right now.
I've managed to use another LCD to replace my defect screen but I had to do electronic and mechanical adaptation to succeed.
here is the link:
Do any other LCD panels work with this iMac?
Best Regards,
Guile
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I'm not 100% sure this is the COF which creates vertical lines but this is a common issue I've seen. To simplify, imagine that the screen is 1440x900 pixels. That means that 1296000 pixels must be driven. The connector is a 30 pins connector and there is only one interface chip per panel which just have hundred pins. To drive all the 1296000 pixels, the only solution is to do multiplexing with the COF chips. So, there is 5 verticals COF (1440 divided by 5 gives 288 vertical lines per chip to drive) and 4 horizontal COF (900 divided by 4 gives 225 horizontal lines per chip to drive). So, multiplexing means that all data coming from the interface chip are duplicated to all the COF (sequentially indeed). If a problem appears before the COF, you will simply have vertical lines evenly spaced, with same color all over the screen. For my own I've never seen that. Just vertical lines randomly spaced, with random color. These lines often appear or disappear according to temp.
No but I believe it can be replaced witha spare from an otherwise identical model.
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How sure are you that the problem is with a COF device and not a surface mount component on the PCB?
The article you linked to is the one I previously read and is what made me start this discussion. I would much rather repair the display I have now then to go through the trouble you went through to replace the display with a different type.
I've done my research on this defective display and can find no comment as to what component made it fail.
Could any of the components on the PCB fail that would cause such a defect? I've also noticed that this defect almost always starts on the right side of the screen directly above the fifth glue tab.
door Slowmac