Qualitron 24K Calculator Teardown
ID: 192788
Description: This is the last calculator guide that I’m...
Steps:
- I’m back again from the thrift store with another calculator! This is the last calculator guide I will be making:) Anyways, this weird thing is called the “Qualitron 24K”. It’s some sort of mid 70’s calculator made by “Qualitron”. I have not found much of anything on the internet about this hunk of old metal, but it looks cool.
- As you can tell, it is currently broken, due to the incredibly annoying non-replaceable 6V lithium cell batteries.
- To begin destruction of this already broken calculator, use a Philips head screwdriver to remove the two Philips screws securing the metal backplate in place.
- Note that there are two different screw sizes! The large one goes where the label is on the bottom, and the small goes on the top!
- After the screws are removed lift the metal backplate off. The green PCB is now visible.
- If you noticed the missing batteries, I already opened up this calculator to remove them. (There was lots of battery corrosion everywhere.)
- I even cut off the wires connecting to the batteries, since it was so gross and disgusting.
- Now, use a flathead screwdriver to unfasten the clips holding the PCB in place. Once two of the four clips are unfastened, pull out the PCB from the calculator.
- Be careful with the keyboard wires connecting to the PCB!
- Now you can see the VFD (Vacuum Fluorescent Display) in all of its glory:)
- The chip powering this calculator appears to be a National Semiconductor MM57134ENW/N microprocessor. Based on the internet, it was also featured in the Sinclair President calculator, made around the same time.
