HP-42S battery drain

[Marcovecchio]

I would like to share what I ended doing to this 42s: I did the switch mod, and it works very well!

I attached some pictures. I had a tiny switch in my parts box, which I fixed to the PCB side with epoxi glue. The trick here is to make the switch control the power of the Saturn processor only, not for the whole machine!

This way, I can turn the switch on, then turn the 42s on using the usual ON key. After usage, turn it off normally with shift+ON, and then, turn the switch off. Power consumption will be minimal, just enough to keep RAM contents.

After turning it on again (using the switch and then ON button) I get a "Machine Reset", indicating the processor restarted, but all memory content is intact. The effect is similar to the "coma mode", or pressing ON, XEQ and +

I think this is the best I can do to this calculator for now. In the future, I think I'll adapt three AAA batteries as an extension to the housing, making it thicker and heavier, but this will be a low priority project for the future.

Eduardo