again about HP41c display features

[aurelio]

Searching for another problem I've found this thread in the ancient "holy" forum and read this:
"I have a number of very early LCD calculators in my collection, some of them of the 'first-batches' yellow LCD type, and not only do they still work fine, but I can't notice any sign of degradation or diminished functionality whatsoever, despite the fact of them being 25+ years old"

Now, my first 41 was a CX halfnut, so that I cant remind it.......the 'first-batches' yellow LCD type, aren't the ones provided with the tall keys?
It means that the "yellowed" look , it's not due to smoke and to the age of the calculator, as I thought an wrote in a previous thread few days ago......
That could be its natural look!

But now I have with me a Tall key very beauty that came affected by the "greeen" desease.

After a cleaning (the block must be completely restored) I tried a test with a spare one but despite the look very nice it does not give signs of life...
I've tried to replace the board: still not working..

Now I've noticed that the display is not the yellow one, it seems a "new batch" one (fullnut of course) but bright like a CV or a CX fullnut one...it seems it has been serviced (display replacement)......the driver mounted on the first C is not the same for the CV-CX boards? That could be the issue?

[Dieter]

(10-21-2016 01:37 PM)aurelio Wrote:  Searching for another problem I've found this thread in the ancient "holy" forum and read this:
...

Aurelio, please forgive me, but even after reading your post several times I am not sure about the exact problem or the question you would like to ask.

For what it's worth, I got both an early 1979 tall key 41C and several later ("halfnut") 41CVs. None of them shows a noticeably yellow or even green display, they all look quite similar after 30...37 years.

In the Seventies, some manufacturers (e.g. Casio and Sharp) used LCDs with a yellow top glass to reduce the negative effects that UV radiation may have. But this is a completely different story.

Dieter

[Ángel Martin]

There are 41 LCDs with a more greenish tint than others. This is not new, and as can be expected those have worse legibility. I'm not sure about the reasons (UV, plastic decay, etc.) but it's definitely a sure thing - I have a couple of units with that type and it's very noticeable.

[aurelio]

(10-21-2016 06:52 PM)Dieter Wrote:  

(10-21-2016 01:37 PM)aurelio Wrote:  Searching for another problem I've found this thread in the ancient "holy" forum and read this:
...

Aurelio, please forgive me, but even after reading your post several times I am not sure about the exact problem or the question you would like to ask.

For what it's worth, I got both an early 1979 tall key 41C and several later ("halfnut") 41CVs. None of them shows a noticeably yellow or even green display, they all look quite similar after 30...37 years.

In the Seventies, some manufacturers (e.g. Casio and Sharp) used LCDs with a yellow top glass to reduce the negative effects that UV radiation may have. But this is a completely different story.

Dieter

Dieter I'm sorry for my poor english....
As Angel wrote in the previous reply there are displays "yellower" or "greener" than others, let me say now "darker" ......to be not misunderstood, and about those I think John Smith was talking in the older post I linked and quoted.
Now, all the tall keys I met up to now, had the darker display, while the last one I handled looks to have like an earlier display, the same I see on fullnut CVs and CXs...so that I thought that maybe was serviced... assuming that it does not work I thought that something could be wrong with that display....for this reason I asked if the most recent displays (not the rounded of course) have a different driver...or if the squared are all the same...this is the question

[aurelio]

(10-22-2016 04:37 AM)Ángel Martin Wrote:  There are 41 LCDs with a more greenish tint than others. This is not new, and as can be expected those have worse legibility. I'm not sure about the reasons (UV, plastic decay, etc.) but it's definitely a sure thing - I have a couple of units with that type and it's very noticeable.

Sure

Here a sample of what I'm talking about the "different" display is the first on the left,. even "brighter" than the CV's one

[hth]

Is the tinted display the kind where you can see the unlit segments and traces?

If yes, these are earlier displays. I have one of these on an early CV (-81) I bought new. They changed to another display (around -83) where you cannot see this, and then later to the halfnut display (-85).

These early displays have a bit different tint, but it has always been like that. Maybe they are a bit less bright as well, but my memory 30+ years later is not entirely clear (either).

Håkan