Date: Sat, 03 Nov 2001 16:50:01 +0800
From: Raymond <[EMAIL PROTECTED]>
Subject: Re: [LIB] 100CT: Vertical white striping on LCD

At 12:14 AM 3/11/2001 -0800, you wrote:
>Date: Sat, 3 Nov 2001 00:08:35 -0800
>From: "Jason Kim" <[EMAIL PROTECTED]>
>Subject: Re: [LIB] 100CT: Vertical white striping on LCD
>
>It doesn't affect the console character-by-character ... it does the exact
>same thing it does in high-res mode: colored areas are slightly lighter (as
>if by a pattern).

That could well be the video buffer memory as well ... remember, at the final stage 
RAM maps straight to the screen.


>Is there any way an LCD could be damaged so that a consistent pattern of
>vertical lines appears across the screen?

Quite possible ... more likely the screen connector cable though IMHO ... all thats 
involved in getting to that is removing a single screw that holds the keyboard down. 
Also try Neil's idea of slightly flexing the motherboard whilst the libby is turned on 
and seeing if it makes a difference (you'll have to run the libby without the bottom 
half of the case to do it properly). Whilst you're at it, slightly flex the screen too 
if you want. Unless your computer has been shocked or something the underlying cause 
is most likely mechanical, doing this will help you narrow it down. 


>Another interesting symptom is that on either very dark or very light
>colors, this is completely undetectable. Only midtones (like grays) are
>affected at all.

If one of the connectors is slightly damaged then this would be expected (this is 
perhaps a simplistic explanation but perhaps something corresponding to the low bit of 
the horizontal address line may be slightly damaged? That would result in every even 
or odd pixel being affected depending on which way it was stuck). Very dark colors 
would not be affected - all off is still all off. Very light colors likewise - the 
pixels are already close to saturation so for the same difference in signal you don't 
see much. You'll get most visible difference right in the middle which would 
correspond to the midtones. Just out of interest, is there any particular hue at which 
this is most visible? At this stage I'm getting into guesswork but if its across ALL 
hues then perhaps it might be more a connector or RAM problem where if it was specific 
hues (or more specifically, if it only affected one of the primary colors - pure red, 
pure green or pure blue) then it may well be the screen itself (thats because the 
video data going through that screen cable should still be indexed color, it should 
only get turned into individual signals for the 3 sets of pixels at the screen end of 
that cable). 


- Raymond

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