domingo, 23 de novembro de 2014

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

HP-35S year 2007 vs 2012

Both have Firmware Rev. 1 (display = 0)



terça-feira, 11 de novembro de 2014


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


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::


Final testing: