iMac Screen fix

Hi Guile

Apologies if this sounds a little naive but would it be straightforward to take a working LM171W02 (TT)(A1) screen (from an old G5 iMac) and combine it with a LM171W02 (TL)(B2) unit that has the lines problem to then install in an Intel iMac?

The two screens are identical in terms of plugs and the mechanical housing but the G5 screen (TTA1) stops my Intel iMac booting or showing any life signs at all other than 1 LED on the board (I thought I'd ruined my iMac after I attempted the replacement).

I would have thought that there would be some parts of the donor screen that could be used to repair the broken bits of the screen with lines or is that impossible?

Thanks

Richard

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Hi Richard,

The answer is no. You can find more information here at the following link:

Can the LM171W02 display be repaired?

https://discussions.apple.com/thread/153...

Regards,

Guile

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Hi Guile

Sorry to be pedantic but do you mean "no it isn't impossible" or "no it can't be done?"

Thanks

Richard

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The reason it stops the iMac from booting is because of the radically different pinout(its actually shorting the screen power to ground), the G5 uses TMDS , while the intels switched to LVDS. Its 2 different technologies that are not in any way interchangeable(this road has been well traveled at this point). if you truly wanted to, i dont doubt LVDS can be converted to TMDS, but i cant see a converter fitting in the very limited space afforded in the iMac.

I understand your reasoning and appreciate the input, because of the physical characteristics and easy availability of this screen it would be fantastic if it would work, it just doesn't seem like the way to go at this point.

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Hi Thanks for that - looks like I'm about to be embarking on your in line solution. A couple of questions though: where is the EEPROM chip located on the old screen and do you have to desolder it (I'm imagining that's the point of no return in this process)? Why are the number of CCFLs an issue - there is still I thought only one connector to the logic board? Finally, how difficult are the mechanical mods - what's involved in getting it to fit in the enclosure? Thanks for your patience - I'm new to all this!

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No desoldering is involved, the EEprom is directly on the PCB and it is written with the info the i dumped from the desoldered EEPROM from an original screen, so as far as the iMac is concerned it is reading the original screen.

The CCFL issue is thus: The CCFL inverter contains 2 high voltage outputs, and the controller chip uses an "open lamp" protection method on each output. If that protection is tripped on either output it will turn off the inverter until next system startup. Which means with no load on both outputs at all times it will not light the CCFL.

The Solution: After studying the data sheet for the controller for quite some time, i was able to determine that the switching times for each out put never actually converge, and are actually directly opposite of each other. for this reason a simple Y cable does the trick just fine.Connecting both outputs to 1 CCFL does not trip the protection, and has been tested reliable for a solid period of 8 hours, as well as many cold starts at this point.

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