This HP 21 scientific calculator was damaged by leaking NiCd batteries. The calculator has tiny LED display that consume quite a bit of current, hence the design of a calculator with a rechargeable battery. The power specs for the charger( found on a small sticker on the back casing ) says 2.5V 500mA, this is huge with compare to todays calculators.
I intend to clean it out and power it up to see if it still works. The liquid from the leaked NiCd battery pack really has done extensive damage to the PCB and the gold plated circuit on the keypad. Look out for the detail pictures.
The serial number moulded to the back of the casing is 1603S10198. This means that it is manufactured in 1976 Jan ( week 3 ). This is probably the 10198th calculator make in the Singapore plant since the start of 1976. That seems to be alot of HP-21 calculators, supposed most are not in landfills or incinerated with the garbage. It is a pity, since a calculator functions is timeless, they could have been resused if not damaged like the one here by corrosive battery leaks.
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