> -----Original Message-----
> something
> making marginal contact on the LCD board. When it’s flexed
> slightly,
> the lines vanish, and the case presses on it just enough to make
> the
> problem crop up.
> [...]
> Is there a common failure mode for these panels or something else
> I
> should be looking at?
See below for what I suspect is your actual problem, but I thought I'd answer
this first: there is a common failure mode which seems to affect mostly M100
displays as far as I know, not the T102. It's pretty common for vertical lines
of pixels reaching halfway up from the bottom or halfway down from the top to
go blank, but they don't come back if you twist or flex anything, and they
don't seem to be related to bad contact but rather to some bad component. I
don't have more detail than that as I didn't get into repair of my bad LCDs - I
bought up a few trashy-looking M100s and salvaged their display modules and a
few other parts.
> I don’t see how the panel itself is connected to the PCB. Perhaps
> there are pads on the top side and it’s simply the friction of the
> panel sitting on the board that does it? The more I poke around,
> the
> more I think it might be the PCB to panel connection.
It certainly sounds like it, based on twisting causing the dead lines to
re-appear. The way that the panel connects to the PCB is through a pair of
what appear to be translucent rubber-like strips (IIRC - it has been a while
since I had an LCD apart so I might be wrong about them being translucent).
This is quite common with LCDs except the strips I am more accustomed to seeing
are made out of alternating black and white segments, so it's easy to see that
they have conductive and non-conductive sections running through their
thickness. The LCD is precisely aligned with the PCB, which has conductive
pads on it, and these strips conduct through to the (nearly invisible) pads on
the LCD panel glass.
The LCD panel is clamped to the PCB by a metal frame which surrounds it and
which has small tabs which fit through notches in the PCB and are bent over to
secure it in place and apply continuous pressure. If you remove the LCD
assembly from the top case, you can put a little extra pressure on different
spots around the perimeter of the LCD by squeezing the top of the metal frame
down against the PCB with your thumb and forefinger. Firm pressure, but not
too much - remember it's glass. You should be able to find the magic spot
where the problem is happening. If you're lucky you might be able to bend the
tabs nearest to that spot to increase the pressure and resolve the problem
without taking it apart.
If you're not lucky, there might be corrosion under the rubber-like strip, and
you'll need to disassemble it and clean it... it's possible, but tedious and a
bit risky. I'm not going into detail on that now because this email is already
getting a bit long. :)
jim
