Backlit Hitachi monochrome LCD display has dark horizontal lines obscuring
much of the displayed text.

I understand that frequently this is due to poor contact between the
printed(?) contacts on the display glass and the conductive rubber(?)
connection blocks.

Is this something that can be repaired? Disassembled & cleaned?

Thanks,
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DaveC

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It's a Hitachi LMG7420 matrix display:

http://tinyurl.com/bflenm

Data sheet: http://www.farnell.com/datasheets/28076.pdf
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DaveC

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DaveC wrote:
Backlit Hitachi monochrome LCD display has dark horizontal lines
obscuring much of the displayed text.

I understand that frequently this is due to poor contact between the
printed(?) contacts on the display glass and the conductive rubber(?)
connection blocks.

Well, that's one possibility - or simply dead drivers.

Either way, it's unlikely to be easily repairable.

Bob M.

Sometimes a gentle nudge of a zebra connector will clear this sort
of thing up, and I often see an opening that's just right for
reaching the zebra connector. It's worth a try. Be gentle; it
doesn't take much t move a zebra connector.

On a typical LCD matrix display like this how many zebras are there? One
along one end for horizontal control lines and one along the top edge for
vertical control lines? Or are the control lines (the ones on the glass) all
brought out to one location?

Thanks,
--
DaveC

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I just took a close peek at the connections. There are no zebra connections.
This has a small pc flex cable soldered to the PCB with the other end laid
against the printed traces on the glass. A silicon rubber block puts pressure
on the back of the cable which forces contact between the traces and the
cable.

Probably the block has shrunk with age and temperature and/or dirt came
between the connections. I'll dis/reassemble everything today and see what
works or doesn't...
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DaveC

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No joy. Symptoms unchanged.

I suspect it might be a failed driver. Not willing to go that far in
diagnosis. A new one is US$150.

FYI,
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DaveC

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On Mon, 16 Mar 2009 01:45:45 -0700, DaveC wrote:

Sometimes a gentle nudge of a zebra connector will clear this sort
of thing up, and I often see an opening that's just right for
reaching the zebra connector. It's worth a try. Be gentle; it
doesn't take much t move a zebra connector.

On a typical LCD matrix display like this how many zebras are there? One
along one end for horizontal control lines and one along the top edge for
vertical control lines? Or are the control lines (the ones on the glass) all
brought out to one location?

Thanks,

The (few) ones i have seen they are top and bottom edges. No clue as
to what is on the various positions.