display problem on thinkpad in 80x25 (text) mode

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I have a thinkpad that has developed a problem in 80x25 (text) mode.
To be clear what I mean, this is the mode the laptop comes up in when
booting, before it switches to graphic mode.  The nt boot list menu is
displayed in this mode, if you allow nt to boot several partitions.
Linux also switches into this mode while booting.  So, does system

I believe that a previous thinkpad had this same problem (or a similar
one) just before dying.

In any case, the problem manifests itself by showing different
characters than what it should.  For example, for space (" ")
characters is shows exclamation marks ("!"), for small letter i's it
shows h's and so on.  Not necessarily everying character, but maybe
50% of them.  In particular, the message "Ok, booting the kernel."
comes out something like "Nk, coothog ..." displayed on a field of !s.

When the screen switches out of 80x25 mode, the problem goes away,
although sometimes small magenta lines appear across certain regions
of the screen that are displayed in certain colors as those sections
are being changed.

The problem is not bad enough that I'm going to trash this laptop.
However, I do worry if it is indicative of impending complete failure.
Moreover, if anyone has suspicions to the cause and what I should
investigate, I would be curious to do so.

One final note, the 80x25 mode can be somewhat mitigated if I push
firmly on the laptop case in a particular place.  The place is near
the power button and also where the body of the laptop connects to the
screen.  Could a loose solder joint cause this behavior?

Also recommendations in the Boston/Worcester/Providence/Nashua area
that actually fixes laptops (and doesn't just replace boards) would be
appreciated, if such a place exists.  The last place I tried did a
cursory look over the laptop before declaring that replacing the
motherboard was the only option and charging me $75 for that info.
(It's not that I mind the $75 they charged (or even more), if I had
confidence that they truly investigated options for fixing the laptop
and did more than just powering the unit on and seeing that the screen
was dark.)  I still have the previous laptop which has died and if it
could be repaired by something less than replacing the motherboard, I
would do so.  If I have to replace the motherboard, it is cheaper to
buy another used copy of the laptop off ebay, which is how I have this
one which may be dying also now.  Note, I don't feel mechanically (or
electrically) competent to make such repairs myself.


Re: display problem on thinkpad in 80x25 (text) mode

Chris F Clark wrote:

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Look at an ASCII table.

Space = b0010 0000
! = b0010 0001

O = b0100 1111
N = b0100 1110

k = b0110 1011

b = b0110 0010
c = b0110 0011

It would appear that bit 0 is always being fetched by the display
controller as the contents of bit 5. 'k' for instance is uncorrupted
because bit 5 happens to contain the same value as the desired contents
of bit 0.

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Nobody fixes personal computers at a component level. Schematics are
unavailable, many of the components are unlabeled, and many critical
components are impossible to probe and difficult to rework (BGA

The reverse-engineering inherent in trying to perform component-level
repairs is completely out of line with the replacement value of a
modern personal computer.

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