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aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

self healing LCD

I have a old (10+ years) LCD thermometer combo where a couple of segments stopped working. First I thought it was low battery, so I replaced it, but it didn't do anything. I did put in a NiZn instead of an alkaline, however. That was a little while ago and I left it on a shelf face down. (it was hanging vertically before) Just a few minutes ago I was cleaning up that space, and guess what, the LCD display looks like new!!!

What would be an explanation for this?

I believe I did make some pictures several months ago, so I will have pictures that can show a 'then', and once I find my digicam, the 'now'.

TIA
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Wacky Races 2012!



leibold
Premium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:10
Reviews:
·SONIC.NET

I'll give that a try on my LCD thermometer. It is almost completely unreadable now. How long did you have it laying face down ?
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aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

At least a couple of months, but when (or if) I find the pictures I made, I can probably give you a better number. Could be as much as 6 months. The higher voltage may have played some role, too, but it's hard to say without doing some additional testing.
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Wacky Races 2012!



tschmidt
Premium,MVM
join:2000-11-12
Milford, NH
kudos:9
Reviews:
·G4 Communications
·Fairpoint Commun..
·Hollis Hosting
reply to aurgathor

I believe most LCDs like that use elastromeric contacts between the display and PCB that can have poor contact integrity over time. I assume (know what they say about assume) laying it down increased the force pressing on the LCD restoring the segments. Just a guess.

/tom


lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to aurgathor

said by aurgathor:

I did put in a NiZn instead of an alkaline

My hunch is that the design has no voltage regulator and the higher voltage made the apparent improvement. It is possible that there will be problems down the line.


tp0d
yabbazooie
Premium
join:2001-02-13
Carnegie, PA
kudos:5
reply to tschmidt

said by tschmidt:

I believe most LCDs like that use elastromeric contacts between the display and PCB that can have poor contact integrity over time. I assume (know what they say about assume) laying it down increased the force pressing on the LCD restoring the segments. Just a guess.

/tom

This is most definitely the case. I have a touchscreen thermostat that I have fixed twice. The screen only displays in sections, and the touchscreen quit working. Took apart the device, cleaned the contacts beween the LCD and the board (its a friction fit connection between the board and display, not a wired/socket). Tstat worked great after that. 2nd cleaning I used some DeOxIT cleaner/lube on all the connections, havent had an issue since.

-j
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if it aint broke, tweak it!!
currently on FiOS (kick aZZ!)


aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1
reply to tschmidt

After a little usage, now it's back to 2 or 3 missing segments anew.
So I guess I really need to get to the connector and somehow fix the bad contacts.

I tried to take it apart, but it's not trivial -- need to cut, and then extend some wires.
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Wacky Races 2012!



SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:3
Reviews:
·Verizon FiOS
reply to aurgathor

The only project I ever worked on that used LCD used the ZEBRA® Elastomeric Connectors. There were a number iterations before we got it right. They were very sensitive to contaminants, alignment, etc

»www.fujipoly.com/products/zebra-···ors.html



aurgathor

join:2002-12-01
Lynnwood, WA
kudos:1

1 recommendation

Due to having several Harbor Freight multimeters (with a free with "any purchase" coupon) I'm already familiar with those connectors...
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Wacky Races 2012!