Recently at a thrift store I found this Texas Instruments TI-5040 electronic calculator. It was really dirty, but it worked fine so in this post I’m just going to talk about how I removed the marks and blemishes. The puzzling thing about this calculator is that it has the old (not original) Tektronix logo on it, but It’s clearly a Texas Instruments calculator. I originally thought it was a promotional gift, but it was built too nicely for being given away for free. My only guess is it was given to accountants who worked at Tektronix.
Anyway, I started by removing the screws on the bottom of the case. Then I removed all the keys so I could soak them in soapy water. I did not remove the electronics from the bottom for cleaning because I was worried about not being able to get the thermal print head back into place. I decided to clean the bottom half when it was all put back together. I started by moistening a paper towel and then putting a generous amount of baking soda on it. Since baking soda is a mild abrasive, when rubbed into the plastic it will remove a very small layer of the plastic, including the stains on it. It works wonders on tough stains. For everything else, I used rubbing alcohol. After I removed the stains I washed the case with soap and a toothbrush while the keys were soaking. Then I left everything to dry. Meanwhile, I vacuumed out the electronics, including the spot where the keys were. And lastly I removed the keys from their soapy bath and rinsed and dried them. Then I left them to air dry the rest of the way.
The next day, the top part of the case and the keys were dry, so I proceeded to reattach the keys and screw the case back together. Once it was put back together, I used baking soda to remove the stains on the bottom half of the case. Then I used rubbing alcohol to remove all the gunk the old cork feet left behind. Lastly I used baking soda on the cord, because it was covered in black stains. Then it was done! I reinserted the paper roll and enjoyed using my super cool retro calculator.
P.S. Sorry that I took so few pictures. I was feeling lazy.
Owen's Tech 