Posts: 883
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Joined: Feb 2006
It is the original design 82120A, later changed to a two pin design.
Think of the 3 pin circuit being the same as the classics, when you plug the charger in, the calculator runs from a separate 5 volt source from within the battery pack while the battery charges. Remove the charger and the calculator runs from battery. The switch is that copper color tab on the center pin of the pack in your photo.
They eliminated the switch in the later design as it could glitch and crash the 41 if it was on when the charger was removed. Any 3 pin packs I rebuild, I modify the circuitry to the later design. This is usually a must as with even minor corrosion, the crazy little flex circuit strip is destroyed beyond reuse. It's easier to toss the extra parts and modify to the later design.
Posts: 244
Threads: 78
Joined: Jan 2009
Thanks for the clarification,
does anyone know where I can find on TAS the necessary batteries for rebuilding this pack ?
take care Alberto