Re: HP21 LED and keyboard problems Message #2 Posted by Dan Grelinger on 16 July 1999, 12:43 p.m., in response to message #1 by thib
I have never seen an HP-21, but have taken apart LED calculators. One reason for LED segments being continously lit is that the calculator has suffered a severe shock, and the fine (and uninsulated) LED connecting wires have been bent and are touching another conductor. Normally they will appear much brighter than normal, since the segment is full on, instead of being strobed, as normal. So you may have another problem perhaps with the display driver. The button problem you describe is not uncommon, and is normally a dirty or worn contact. I doubt that the battery change caused either of these problems.
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