|Re: HP-32E missing digit|
Message #4 Posted by Luiz C. Vieira (Brazil) on 20 Mar 2012, 1:14 p.m.,
in response to message #3 by Matt Agajanian
I actually do not know what diode is the one you mention because in all SPICES, the whole LED assembly and the keyboard are directly connected to one main IC, the big one. In the HP32E there are two other IC's, a ROM and a RAM.
The LED module has only the LED's array to be scanned by multiplexing circuits in order to 'light them up', one digit at a time (very fast, human eyes cannot 'see' them blinking). If the common terminal of one digit (not sure if they are common cathode or common anode) fails, the whole digit does not lit.
The twisting maneuver is something that I apply to my calculators. I take it with both hands, bottom an top (closer to the LED display), and gently twist it along its axis. My spices are not that solid, they all allow a little twist, which is enough to maintain contact in the solderless units. As I mentioned before, if twisting is not an option, opening the unit is somehow better.