On Feb 6, 4:51*am, Sylvia Else wrote:
On 6/02/2012 7:58 PM, N_Cook wrote:





Sylvia *wrote in message
...
After operating OK since the repairs I did after dropping a curtain pole
on this radio a month or so back, the LCD is playing up.

If I perform an operation that clears the display, and enter an 8 digit,
it looks normal enough. If I enter a second 8 digit, some of the
segments of both digits (the same ones in each case) become fainter. If
I enter a third 8 digit, the segments become fainter still, and so on,
until they're pretty much invisible.

This suggests an issue with one (or more) of the backplanes.

The signals going in look normal enough, and in particular the backplane
signals don't change as I enter additional digits.

Any thoughts before it ends up on the tip?

Sylvia.

Is there a contrast control that got broken as well?
What other LCD legends etc other than the main 8 digit display ?

Can't see anything that adjusts contrast.

The LCD doesn't have that much other than digits, but those that it has
seem to work normally.

The digits appear thus

* XXXXXX
X * * *X
X * * *X
X * * *X
* ......
. * * *.
. * * *.
. * * *.
* XXXXXX

Where XXX denotes segments that work, and ... denotes segments that don't..

All the digits are failing in the same way, including a small digit that
denotes a channel number.

Since my original posting, I surmised, by cutting tracks, that these
segments share a segment common, as do the top three. So then I
connected them the other way around, with the result that the digits
come out wrong or garbled, but the same three segments misbehaved.

The connection to the LCD is via an eltroconductive rubber strip, which
seems OK. Seems to me that the LCD itself is failing. Seems a strange
failure mode though.

Sylvia.- Hide quoted text -

- Show quoted text -

HAd a similar problem with an LCD on a controller pendant that was
dropped. On desassembly of the display module, it was found that, as N
Cook suggested, one corner of the display glass back plane was
cracked, disconnecting two metalization tracks into the display.
Unfortunatly, the breaks were under the epoxy seal between the top and
bottom plates of the display, making a repair with silver condictive
paint impossible. I was able to replace the display plate with an
identical one from an obsolete pendant and get the newer one working
properly.
Neil S.