How to open a HP 28S calculator

How to open a HP 28S calculator

How to open a HP-28S calculator

Index
  1. Problem
  2. How to open the HP28S (right side)
  3. Cleaning the contacts
  4. How to open the HP28S (left side)

See also the next post for creating a new HP28S case

Problem

Key row ‘Y’ to ‘)’ and ‘EVAL’ to ‘-‘ are not working

How to open the HP28S

Since I could not find any photo instructions on how to open a clamshell calculator HP 28S, and I would like to fix this problem, I decided to read up on the different text descriptions on how to do it and started to document it with pictures.

So first set of pictures from today 25.Jul.2017

Some close-up pictures

Next step: (in a few days)
I am buying a small used drill press or maybe just a stand for my drill, so I can remove the top of the melted plastic peg/pins.
Today August 5th 2017 I picked up the drill press.

Cleaning the contacts

We now have the right side (the one with the display) open and the idea is that if a contact is dirty it could prevent a whole row or column of keys to NOT function. Well lets try cleaning them

What did I clean

How to open the HP28S (left side)

Lets open the left side

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As mentioned above, the next step it to put it back together. Well one way is to just glue it or weld the many plastic pegs with a soldering iron. I am trying a different approach with this. See my next post, for creating a new HP28S case.

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