HP's Hall of Fame

[Steve Simpkin]

(02-12-2023 07:19 PM)TellyS Wrote:  

(02-12-2023 06:16 PM)Steve Simpkin Wrote:  Try applying pressure on the area between the top row of keys and the LCD while pressing the ON button.

I tried that it worked! Thank you! I need to apply pressure on that area whenever the ON button is required (adjusting contrast, or even turning the calculator off). So, what is happening under the LCD that affects a key so far away?

There is a foam piece under the front cover of the case (between the bottom of the display and the top row of keys) that keeps the keyboard circuitry flex PCB connected to the main board. As this foam ages and shrinks, it can cause some keys (particularly the ON key) to not respond.

It is possible to repair this but it not easy. Most involve opening the calculator.
Here is more information on that route and it also shows the foam strip.
https://documents.epfl.ch/users/f/fr/fro...epairs.pdf

Here is another method of repairing this issue without opening the calculator, but it may not always work.
https://www.hpmuseum.org/forum/thread-10538.html