Vertical line of dead pixels on 50g LCD

[Sergio]

Hi to all!

I recently had a problem with the LCD of my 50g. While working on some calculations with it a vertical line of dead pixels showed out of nowhere. I do keep it near me most of the time when I travel, but besides a padded case of a 48g I bought for it I keep it inside an EVA hard case for extra protection so I don't think it's been hit. I ran a self test of the LCD and in one of the animations (?) it works, and in others it doesn't, this led me to think this might be software related. Does anyone have a suggestion to what to do in this case before taking to the shop since it's no longer under warranty?

Thanks in advance for your help.

[brickviking]

(10-04-2017 03:18 PM)Sergio Wrote:  Hi to all!

I recently had a problem with the LCD of my 50g. While working on some calculations with it a vertical line of dead pixels showed out of nowhere....

You wouldn't have posted on the forums at Casiopeia.net, would you? I'm glad to see you made it here, though the laugh is, my reply to that post made it to you after you'd already posted here.

I personally can't suggest anything much, aside from saving your home data and port data (:1, :2) to the computer or SD card, then doing a full reset of the calculator. (ON+F1+F6). Others with better knowledge of the hardware can advise if that's overkill or not.

(Post 111)

[mfleming]

(10-04-2017 03:18 PM)Sergio Wrote:  Hi to all!

I recently had a problem with the LCD of my 50g. While working on some calculations with it a vertical line of dead pixels showed out of nowhere.

If it is always the same line of pixels, then most likely you are experiencing a connection failure between the main printed circuit board and the LCD. This problem eventually happens with all of the HP48 models due to age. I don't recall hearing anyone describe the same problem with the 50g, but the construction of the 48 & 50 are similar enough to make me suspect this might be the cause. You can try pressing down on the middle of the case just below the LCD screen the next time the dead pixel line appears. If the pixels return when you press and disappear when you release, then it is almost certainly a physical connectivity problem.

The fix for the HP48 is simple but requires opening the case, which is by no means simple (believe me, I know firsthand!) Not sure if the 50g is any easier but I suspect someone has documented the procedure here on the site. If I stumble across it myself I'll post a link. Otherwise search MoHPC for a phrase like "50g dead pixels" or "open 50g case" using an external search engine like Google and the specifier

site:hpmuseum.org

You'll get much more targeted search results than if you use the search engine built into the site.

HTH,
~Mark

[Sergio]

Thanks mfleming and brickviking for your answers.
I'll certainly try your suggestions, in my research a came upon the article related to this failure in the 48 series, I hope it doesn't come to having to open the case to repair it, it seems in the 50g there are 2 screws under the lcd screen which you have to pull to access, I don't think that will ever look as nice once that's done.
But, hey, this is like helping a friend in need, you do all you can.
Thanks again, I'll let you know how it goes.

[brickviking]

Did you ever find out what was amiss with your 50G? I was rattling through old posts and came across this one, I haven't seen any replies from you yet.

(Post 180)

[BINUBALL]

I found this thread while googling. When I use newRPL, If there are many numbers and string on stack like below. There are vertical light black line around numbers and string.

I feel uncomfortable with this. Is this dead pixels? I've tested 50g's screen pixels by making 131×80 black grob. But I think every pixel is ok on this test.

Code:

::
80 131 MAKEGROB INVGROB
;
@

[franz.b]

(04-06-2021 03:01 AM)BINUBALL Wrote:  I found this thread while googling. When I use newRPL, If there are many numbers and string on stack like below. There are vertical light black line around numbers and string.

I feel uncomfortable with this. Is this dead pixels? I've tested 50g's screen pixels by making 131×80 black grob. But I think every pixel is ok on this test.

Code:

::
80 131 MAKEGROB INVGROB
;
@

it seems to me a problem of flat batteries and / or badly adjusted contrast ...

[SammysHP]

The display controller used the the HP 39/49/50 etc. seems to have problems driving all columns with the same voltage independent of its content. Maybe using the grayscale mode makes it worse. Also contrast is set too high which makes it more obvious.

[BINUBALL]

Thanks for your all reply.

(04-06-2021 09:01 AM)SammysHP Wrote:  The display controller used the the HP 39/49/50 etc. seems to have problems driving all columns with the same voltage independent of its content. Maybe using the grayscale mode makes it worse. Also contrast is set too high which makes it more obvious.

I set contrast high to show problem obviously.

(04-06-2021 07:34 AM)franz.b Wrote:  

(04-06-2021 03:01 AM)BINUBALL Wrote:  I found this thread while googling. When I use newRPL, If there are many numbers and string on stack like below. There are vertical light black line around numbers and string.

I feel uncomfortable with this. Is this dead pixels? I've tested 50g's screen pixels by making 131×80 black grob. But I think every pixel is ok on this test.

Code:

::
80 131 MAKEGROB INVGROB
;
@

it seems to me a problem of flat batteries and / or badly adjusted contrast ...

Yes, my 50g has all two problem. 5.0V low battery and high contrast..