Texas TI-58: Repairing the keyboard bounce and miss to register keystrokes

Dissemble the keyboard.

Prepare the keyboard 9 rows  joint points by tinning them.

Prepare the 9 Dome row sets by tinning the joint points on both sides.

Put back the 9 dome row sets by soldering them to the keyboard 9 rows joint points.

Re-apply the plastic cover to the 9 sticky dome row sets.

Testing. No bouncing and no missing keys.

35 years between these two calculators: HP-35 vs HP-35S

HP-35S year 2007 vs 2012

Both have Firmware Rev. 1 (display = 0)

2007:

2012:

TEXAS TI-59

For many, the best calculator in the 70's. Powerful and low cost made it so popular.


Card Reader.

Power adapter / Charger
Model AC 9900/H  6.2VAC / 200mA / 3VA

Replacement Battery - wrong type, soldered to the calculator, and dead

 

After cleaning

Documentation

Read Heads signal:

Keyboard replacment:

Initial testing:
Three jumpers are needed in order to a successful power On.
On the 8-pin female connector, from left to right in the picture:
- Connect together the 2nd, 3rd and 4th pins (power on switch);
- Connect the 5th and the 8th pins (card reader sensor);
- Connect the 6th and the 7th pins (card reader sensor).

Repairing the battery connector::

Assembling:

Final testing: