Illuminating the HP49G LCD display?

[n3mmr]

I tested my 49G the other day, and it had developed keyboarditis, i e to start it up you have to push hard on the bezel above the softkeys in order for it to wake up.

So: I'll have to open it up and fix the kbd connector.

So I thought I might try to add some LEDs arranged near the display to improve readability of the rather dim LCD.

Has anybody else tried this?
What LEDs could you use? Where should you connect the LED to minimize the strain on the electronics and so it would only light up when the calculator is on?

[Vtile]

(01-07-2022 07:16 AM)n3mmr Wrote:  I tested my 49G the other day, and it had developed keyboarditis, i e to start it up you have to push hard on the bezel above the softkeys in order for it to wake up.

So: I'll have to open it up and fix the kbd connector.

So I thought I might try to add some LEDs arranged near the display to improve readability of the rather dim LCD.

Has anybody else tried this?
What LEDs could you use? Where should you connect the LED to minimize the strain on the electronics and so it would only light up when the calculator is on?

I suppose you have opened it already, anyway if the internals are similar than in 50g there is no much room for leds. Only point where the leds could work is an edge of the LCD glass edge, but the illumination effect is rather poor and in 50g only SMD devices fit physically IIRC. SD card and IIRC serial port did have place to make software controller FET switch for leds. One option would be removing the entire back coating of LCD and replacing it with something illumination friendly diffusor, but I never did go that far on re-engineering.

[Garth Wilson]

See this topic: https://www.hpmuseum.org/forum/archive/i...d-614.html

[Dave Britten]

Back in the late '90s when I got my 49G, I found that the readability was improved tremendously by simply removing the plastic lens covering the LCD. This leaves the LCD sitting out in the open, much like on the 48. I grabbed a spare 5.25" floppy disk and cut a new bezel from the outer jacket and stuck it on to make it at least sort of nice looking.

https://i.imgur.com/HbMBTuz.jpg

Looks pretty good. The keyboard still sucks though.

[Massimo Gnerucci]

(01-28-2022 02:36 PM)Dave Britten Wrote:  Back in the late '90s when I got my 49G, I found that the readability was improved tremendously by simply removing the plastic lens covering the LCD. This leaves the LCD sitting out in the open, much like on the 48. I grabbed a spare 5.25" floppy disk and cut a new bezel from the outer jacket and stuck it on to make it at least sort of nice looking.

https://i.imgur.com/HbMBTuz.jpg

Looks pretty good. The keyboard still sucks though. :)

What really sucks is that 'ALG' on the upper right... :P

[Dave Britten]

(01-28-2022 03:28 PM)Massimo Gnerucci Wrote:  

(01-28-2022 02:36 PM)Dave Britten Wrote:  Back in the late '90s when I got my 49G, I found that the readability was improved tremendously by simply removing the plastic lens covering the LCD. This leaves the LCD sitting out in the open, much like on the 48. I grabbed a spare 5.25" floppy disk and cut a new bezel from the outer jacket and stuck it on to make it at least sort of nice looking.

https://i.imgur.com/HbMBTuz.jpg

Looks pretty good. The keyboard still sucks though.

What really sucks is that 'ALG' on the upper right...

Yeah, I only popped batteries in to take this picture. I wasn't going to use the keyboard any more than necessary.

[rprosperi]

Sorry, leaving it in ALG mode guarantees you will use the keyboard more. IIRC, even turning a machine off takes more keystrokes in ALG mode...

[RMollov]

(01-28-2022 06:30 PM)rprosperi Wrote:  Sorry, leaving it in ALG mode guarantees you will use the keyboard more. IIRC, even turning a machine off takes more keystrokes in ALG mode...

what if he takes batteries out without keystrokes at all?