HP 48 HG Calculator LCD Screen

[jpazos]

Hello

I have a 48G time ago, and I saw the screen changed to black or darker. Who could replace it? or where could I buy the LCD screen replace part?

Best regards, Javier
913-937-7895
javier.pazos@hotmail.com

[Steve Simpkin]

Have you tried adjusting the LCD contrast by holding down the ON button and pressing the + or - keys repeatedly?
I don’t recall hearing that many cases of the LCD itself going dark over time.

[ijabbott]

Is it a dark rectangle (covering just the whole of the pixel area) or a dark blob? A dark rectangle may just need a contrast adjustment, but a dark blob in the middle of the screen is probably due to a problem with the polarizing film layer of the LCD.

[jpazos]

Really, I suppose the LCD is damaged. I am attaching a picture. Do you know where can I buy the screen part? or who could fix it?

best regards

Javier

[BillBee]

If you do a search for "HP 48g LCD repair" you will find some pretty good DIY guides on this site and others.

You will most likely have to find a donor unit.

Unfortunately, I do not know of a service to refer you to for the 48s.

-Bill

[jpazos]

Ok, Bill.

Tks, I will try to find a LCD screen. Did you see the picture?

[Jeff_Birt]

(08-29-2022 09:26 PM)jpazos Wrote:  Really, I suppose the LCD is damaged. I am attaching a picture. Do you know where can I buy the screen part? or who could fix it?

best regards

Javier

This is a problem with one of both polarizing films going bad. Many times it can be fixed it depends on how the LCD is assembled.

Starting about the 2:23 mark in this video I show taking apart a smaller LCD with a similar problem. I did not have the correct reflective polarizer film for the back of the LCD but use normal polarizer with a sheet of white paper behind it. The results were not great, but better than it was originally. I did get in some of the proper film but have not had a chance to try fixing it properly.

[BillBee]

(08-30-2022 05:21 PM)jpazos Wrote:  Ok, Bill.

Tks, I will try to find a LCD screen. Did you see the picture?

Yes, I saw the picture and I have a GX with the same issue but not as dark.

TBH for a 48G I would be tempted to just buy a dead one with a good screen. If you are going to open a 48 its best to try on a parts unit.

This should give you some insight:

https://documents.epfl.ch/users/f/fr/fro...epairs.pdf

Jeff does give an option too.

-Bill

[Brad Barton]

I've been told that you can also use a screen from an HP-39g. They're relatively cheap to buy, and also are made using the high-contrast black lcd screen like the later 48's.

It's a good idea to practice opening a donor or "parts-only" 48 before you try this. They are stubborn little units, and it's easy to ruin the case when you open it. Han's fingernail clipper tutorial works pretty well, but there are other ways I haven't tried.

https://www.hpcalc.org/hp48/docs/opening/ contains a whole series of articles on opening the calculator. Study up!

Brad

[hibiki]

The same happened to my HP48GX (and HP32SII and HP42S). I think it is the reflective pelicule in the back of the LCD. I could repair one of my HP32SII simply replacing the reflective pelicule (adhesive) with an aluminized pelicule from another damaged LCD. Maybe even a white paper sheet could work. The glue in the last layer (the reflective pelicule) decays with heat and time and makes the display dark. The glue should be cleaned from the LCD. Worths a try. I have not dissassembled my other calcs with the same problem, but someday ...
See the same problem in a multimeter display:
https://youtu.be/yZq2w5EHRNg