POV-Ray : Newsgroups : povray.off-topic : Also... why? Server Time
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  Also... why? (Message 1 to 6 of 6)  
From: Invisible
Subject: Also... why?
Date: 7 Dec 2007 07:03:30
Message: <47593692$1@news.povray.org>
The display on my mum's microwave oven is doing something strange.

It's a backlit LCD. Usually it displays the cooking time as it counts 
down. But now some of the segments only turn partially black. And 
sometimes segments fire when they shouldn't. Very odd.

Anybody have theories about why it's doing this? Is it likely to be fixable?


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From: scott
Subject: Re: Also... why?
Date: 7 Dec 2007 07:49:29
Message: <47594159$1@news.povray.org>
> The display on my mum's microwave oven is doing something strange.
>
> It's a backlit LCD. Usually it displays the cooking time as it counts 
> down. But now some of the segments only turn partially black. And 
> sometimes segments fire when they shouldn't. Very odd.
>
> Anybody have theories about why it's doing this? Is it likely to be 
> fixable?

The LC itself it screwed (as in the optics/materials inside the glass), it 
happens a lot with these uber-cheap passive LCDs, they don't have very 
strict testing or quality requirements.  It's due to moisture and other 
contaminents getting inside the side of the glass and generally screwing up 
the electrical and optical properties of the LC (mostly reducing contrast so 
the disaply becomes less and less readable).

If, however, the segments are perfectly black and white but just showing 
wrong digits, probably something wrong with the driver electronics (although 
seems unlikely).


likely to be more expensive than a new microwave...


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From: Invisible
Subject: Re: Also... why?
Date: 7 Dec 2007 07:52:24
Message: <47594208$1@news.povray.org>
scott wrote:
>> The display on my mum's microwave oven is doing something strange.
>>
>> It's a backlit LCD. Usually it displays the cooking time as it counts 
>> down. But now some of the segments only turn partially black. And 
>> sometimes segments fire when they shouldn't. Very odd.
>>
>> Anybody have theories about why it's doing this? Is it likely to be 
>> fixable?
> 
> The LC itself it screwed (as in the optics/materials inside the glass), 
> it happens a lot with these uber-cheap passive LCDs, they don't have 
> very strict testing or quality requirements.  It's due to moisture and 
> other contaminents getting inside the side of the glass and generally 
> screwing up the electrical and optical properties of the LC (mostly 
> reducing contrast so the disaply becomes less and less readable).
> 
> If, however, the segments are perfectly black and white but just showing 
> wrong digits, probably something wrong with the driver electronics 
> (although seems unlikely).
> 

> is likely to be more expensive than a new microwave...

Damn.

Well I only noticed it yesterday. Happened after I moved the machine 
from one room to another. I was wondering if maybe it was just some 
moisture or something and it might go away after a while. Or maybe I 
just need to jiggle the display gently and it might work again.

But I guess not. :-S

Still, the oven still cooks food, so...


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From: scott
Subject: Re: Also... why?
Date: 7 Dec 2007 08:00:25
Message: <475943e9@news.povray.org>
> Well I only noticed it yesterday. Happened after I moved the machine from 
> one room to another.

Are you looking at it from the same angle as before?  Often when it starts 
to screw up it is only visible from certain angles and gradually gets 
worse...

If it only started happening after the move, then I'd at least open it up 
and try reseating any connectors, worth a try and nothing to lose - apart 
from maybe microwaving your hand in the process ;-)


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From: Mike Raiford
Subject: Re: Also... why?
Date: 7 Dec 2007 08:10:37
Message: <4759464d$1@news.povray.org>
scott wrote:

> If it only started happening after the move, then I'd at least open it 
> up and try reseating any connectors, worth a try and nothing to lose - 
> apart from maybe microwaving your hand in the process ;-)

Thankfully microwave ovens have a myriad of safety interlocks to prevent 
that from happening.


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From: Kyle
Subject: Re: Also... why?
Date: 7 Dec 2007 08:24:26
Message: <phhil39v5476k2eruc86kra9qbhk5g8503@4ax.com>
On Fri, 07 Dec 2007 12:03:29 +0000, Invisible <voi### [at] devnull> wrote:

>Anybody have theories about why it's doing this? Is it likely to be fixable?

Most LCD assemblies are constructed of a sandwich of circuit board, two elastomer
conductors and the LCD itself.  The elastomer conductors, consisting of layers of
conductive and non-conductive
materials, provide conductivity between contacts on the circuit board and contacts on
the LCD itself.  The sandwich of circuit board, elastomer conductors and LCD is
typically held together by
pressure from the metal housing surrounding the LCD.  There are usually tabs on the
metal housing that are bent over or twisted to hold the circuit board in place.

With all this being said, what typically causes the problem you've described is bad
conductivity between the circuit board and LCD.  They can sometimes be fixed, but it
is a frustrating task.  It is
typically more cost effective to just replace the LCD assembly, and it'll save your
sanity.


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