HP 32SII success and woes

[Sanjeev Visvanatha]

(02-11-2015 03:55 PM)Bruce Larrabee Wrote:  The metal plate is grounded but only really matters if the unit has a buzzer and only when the buzzer has only one spring contact.

As for the gibberish on the screen, if there is a key or combination of keys that could cause this (a big if and I don't know the answer) then there could be a short in the keypad matrix. I see this all the time. If it is so it is possible to dismantle the keypad and clean the matrix. (I did one yesterday.) This is not easy though.

Whatever you do don't throw the calculator away!

Hmmmmm - so I connected the central top Twisty clip holding the PCB in place to the negative battery terminal (assuming this is equivalent to ground - I am not an EE). Voila, the unit operates normally, but shows the low battery indicator.

This leads me to speculate that there is a grounding issue on the PCB. That metal plate also serves to protect eyes/objects from touching the PCB and the integrated circuit. It is possible the previous owner was not careful in this regard.

So, it looks like I am opening it up. I may try my hand opening a 10B first (no offense to anyone here), before working on this unit.

Any thoughts on the grounding issue are welcome.

Thank you all for your input and time.