Texas TI-34 solar scientific calculator

 Nice calculator powered by a single power source based on a four elements solar panel.
This one was made in 1987, November.

This machine was heavily used and abused, showing dents and marks all over the place, and heavy paint worn on the metallic front panel.
It was even opened and the PCB removed by destroying the plastic rivets and later fixed back with cyanolit glue that have also stuck the keyboard membrane to the PCB because the glue leaked thru the PCB holes.

But still works fine after all these years and misuse.

Forensics result: 8.999998637 

(9 sin cos tan atan acos asin)

Mode Hex: NOT(FFFF) = FFFFFF0000

Mode Dec = -65536

Back cover label:

Texas Instruments

I-1187

Assembled in taiwan

R.O.C.

 

The PCB is fixed by plastic rivets in the keyboard area, and screws in the processor/display/solar panel area.

 

 SoC processor: Toshiba T7988  8740H Japan

PCB ref. 10TI34-21B

Power supply regulator: a 1.75V LED and a 22uF capacitor in parallel with the 2.2V solar panel.

 

LCD display. Zebra strip used to connect it to the PCB.

 

Four elements 2.2V solar panel from National. Two zebra strips used to connect it to the PCB.

Power supply.

The solar panel generates 2.2V unloaded (off-circuit)  under strong light, and 1.75V under load (in-circuit), due to the tiny axial 1.75V LED installed in parallel.

The 22uF capacitor gives about 10 to 20 seconds memory contents retention under zero light conditions.

 

The tiny axial 1.75V LED can be seen here being tested off-circuit.