Display problems after replacing IBM lap top main board
- From: Rick <rickajho@xxxxxxx>
- Date: Mon, 21 May 2007 02:18:52 -0400
Hi
IBM ThinkPad A21m 2628-PRU in question.
I had to replace the main board due to the known "lock up" problems on
some IBM models. Did it by the book - used the IBM Hardware Reference
Manual for disassembly procedures.
Now the display is screwed up. The IBM logo on boot is skewed about 40
degrees and off center. (Interesting look, but not right.) When W2K
loads the right two inches of the display are black. And the display
"scrolls" off the bottom of the screen and isn't visible. In this mode
it looks something like it's displaying 768x1024 instead of 1024x768.
The same thing happens in DOS booted diagnostices - the display runs off
the bottom of the screen, but it does fill the entire screen to the
right edge.
In W2K if I change out of "stretch" mode (Fn + F8) the display shrinks
to about 4" wide by 6" tall, placed on the bottom left of the screen.
Display is normal in all modes on an external monitor. Diagnostics
reports no problems with the VGA system. The back light on the lcd
display is working fine.
On this IBM, probably other IBM's as well, the display panel is
connected to a "sub card" via a *heavy* flat cable. (It's reinforced,
and so stiff it has to be screwed down to the sub card hold it in place.
It's not any kind of thin film type of cable.) The sub card connects to
the main board. The sub card acts as a pass through for the display
connections to the main board, contains the status LED's, and the lid
close switch.
Reseating the sub card and the display panel flat cable hasn't helped.
Lifting or pressing on the flat cable doesn't change anything - the
display is rock solid - but just wrong.
Does this sound like a simple LCD flat cable failure? I haven't ventured
into the insides of the display yet so I don't know if there is a cable
failure lurking in there. Removal of the LCD panel wasn't required -
just the cable connection to the sub card - to replace the main board.
One other point is the IBM reference manual has you putting the display
into positions you wouldn't ever do in routine use - flat open at a 180
degree angle - as part of the disassembly process *before* you can get
access to disconnect the display cable from the sub card.
Anyone seen this problem before on an IBM lap top? Any troubleshooting
suggestions appreciated.
Rick
.
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