This is my Texas Instruments TI-SR10 electronic slide rule calculator. Released in 1973, this calculator was Texas Instrument’s first “scientific” calculator, using the TMS-0120NC integrated circuit with four other chips in this system.

Unfortunately, the board, as you will see below has some corrosion on it. I tried to fix it, but one of the chips might be damaged beyond repair. The LED bubble screen also is corroded, with disconnected solder joints to the main board.

It features a:

12 digit bubble LED display.

power by 3 AA batteries.

A competitor to the HP-35 of the time.

TMS0120 single chip system with 4 display driver chips for computation.

To begin teardown of the calculator, use a Philips head screwdriver to remove the two screws holding the plastic case on from the back.

I recommend that you should keep track of the screws, as I accidentally dropped one on my floor which ended up underneath our fridge, and took way too long to retrieve…

Once you have taken out the two screws, use your hand to remove the back case from the calculator.

There are two wires leading to the battery module.

Try not to damage them when opening. The red electrical tape is about to be replaced by solder, since when I first opened the calculator, I accidentally damaged the wires because they were so brittle.

Here is the main PCB. The board has the TMS-0120-NC calculator-on-a-chip system paired with 4 display driver chips.

The board has some old carbon resistors, along with some interesting diodes and capacitors.

The PCB also does not have a solder mask on the front side, as only the back does. This gives the board an interesting “clear” look to it, which I like.

To access the LED display board, there are two small screws that need to be removed. You can use a Philips head screwdriver for this.

Next, use a flathead, opening pick, or just your bare hands to remove the plastic cover covering the LED board.

It is ironic that the plastic cover says “DO NOT REMOVE” and “WARRANTY VOID”. This must have been pretty scary when this calculator was new in the 70’s, as it cost well over $150, in 1970 dollars!

To see the little red LED’s on the display board, just pull up on it until it slides backwards out of the case.

The wires are extremely brittle and weak!

There are 12 LED’s encapsulated in a red plastic case to protect the silicon chips underneath holding all those tiny LED’s.

The small red LED modules also act like a lens, magnifying the tiny LED’s on the minuscule silicon surface underneath.

Thanks for supporting and viewing this teardown! I appreciate it. I hope that this is interesting and or mildly informative or useful for someone actually wanting to repair their calculator. But this guide is a teardown. Maybe I will make an SR-10 repair guide, if I eventually fix this broken calculator.