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T21 LCD Colors Inverted

My IBM T21 was running well until the LCD cable went bad, indicated by the backlight going out. I replaced it, but I was given a new type of cable. The FRU 27L0519 has been replaced by the FRU 27L0640, and should be compatible, according to ebay stores and IBM themselves. However, after installing the cable, all colors are inverted on the screen, and there is a noticable flicker associated with it. Why is this happeneing? Is there an easy fix? Can anyone help?
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jtrinklein
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jtrinklein
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1 Solution
 
rindiCommented:
Either you didn't attach the cable correctly (if this is a flat cable that probably isn't possible), or then it isn't compatible with your system as IBM noted. Use your old cable.

A backlight going out would either indicate a bad inverter board, which you can probably get for a few $'s via ebay, or the backlight cable might be bad. This cable is not the same as the monitor cable, and it usually only has 2 leads. Even if you can't get that specific cable you should be able make your own cable for that, just make sure you connect it from the correct leads to the correct connectors.
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jtrinkleinAuthor Commented:
The cable cannot be attached incorrectly. The old cable is defective. The backlight is operating properly; its the LCD display elements that are dull and flickering. The cable is too complex and small in size to engineer a replacement cable and the wiring is not straight forward.
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jtrinkleinAuthor Commented:
P.S. The inverter board is new
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rindiCommented:
You mentioned the backlight going out. The backlight isn't connected to the rest of the LCD electronics and directly attached to the inverter, which normally has a separate connector the rest of the PC. A bad LCD cable wouldn't cause the backlight to go out.

anyway, if the colors are wrong after you changed the LCD cable, and you didn't connect it incorrectly (which in my other post I mentioned was hardly possible and you have now confirmed that), then that new cable isn't compatible, even though IBM said it was. Sometimes notebooks, even if they are the same model, use different displays inside from different manufacturers, so it is possible that this cable may work inside one t21 and not the other...
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jtrinkleinAuthor Commented:
The LCD data cable and the LCD backlight cable and the keyboard illumination light cable are all in one - all three share the same flex cable.

It has been my suspicion that the cables are not compatible, but I've been reassured many times of the opposite. I may end up securing the original cable type.
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rindiCommented:
That's strange, normally all cables to inverters and backlights are separate, due to electrical and safety reasons.
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jtrinkleinAuthor Commented:
I believe that the entire IBM T series uses only one cable. It is rather unusual in my experience, but keeps it simple.
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CallandorCommented:
I don't know a lot about IBM T21's, but here's a picture of another LCD cable for comparison: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=6833405666&category=51152.  Any chance of one or more of the pins being damaged?
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jtrinkleinAuthor Commented:
I've checked the pins and they all appear OK. The cable in that ebay listing "...519" is of the same form but with a different coating than the new "..640". The cable in that ebay listing is prone to breakdown as mine did.
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CallandorCommented:
I found a picture of the 640: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=6865247697&category=42188

Given how cheap these are and the difficulty of diagnosing what the problem is, would getting a second cable be out of the question?  All cables, even new, are not guaranteed to be working properly until proven so.
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jtrinkleinAuthor Commented:
Actually, I thought the same thing and bought another cable (which I first thought was different, but it ended up also being the 640). It also did not work.
I just don't know how IBM can say that the cable is compatible, and then have it not be. Perhaps the LCD is of a different model? I thought that maybe a BIOS update would fix the problem, but that didn't work either. I thought there might be some firmware for the video chip, but that does not exist. Maybe its time to "throw in the towel"...
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CallandorCommented:
Unless you want to take a risk and get another 519 cable...
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