Restoring Function to a 1970s Texas Instruments TI-55 Calculator

The Texas Instruments TI-55 was a very popular scientific calculator from the late 1970s. It was relatively inexpensive ($59.95 in 1978), had scientific, statistical and trigonometric functions and was easily programmable with up to a 32-step sequence of keystrokes. That may not sound like a lot but it was at the time!

This TI-55 was not working when first connected to power. In this video I make it work again.


Learn_about_the_Texas_Instruments_TI-55
•https://americanhistory.si.edu/collec....
•https://en.wikipedia.org/wiki/TI-55
•http://www.calaquin.com/2019/01/revie...
•http://www.datamath.org/Sci/MAJESTIC/...


TI-55_Owner's_Manual
•http://www.datamath.net/Manuals/TI-55...


Chapters:
0:00 Introduction
0:21 Examination
1:30 Testing the Calculator
1:46 Battery Pack BP-7 & its dirty secret
2:32 Opening the Battery Pack
3:53 Choosing strategy for repair
4:34 Testing the Calculator (again)
4:54 Doing the repair
5:17 Reflections on TI-55 Design
5:59 Conclusion