My newly acquired HP19C seems to have died on me

[Katie Wasserman]

(12-16-2014 06:57 PM)Harald Wrote:  I finally found the time to play with the 19C. Thanks for all your help! It was a bad transistor. For what ever reason it had a base emiter voltage of 0.2 Volts. After replacing it with a BC817 I now have a fully working printer! :-)

Unfortunately the 19C now has another problem. While typing in numbers, funny things happen. The display suddenly fills with zeros for example. Or somethimes segments c, d, e and g are lit on a few digits.

It seems, at least judging by it's smell, the calculator has been stored in a very damp environment for some time. Maybe the components suffered from that.

I'm glad to hear that you got the printer working at least! The other issues might be not enough current getting to one or more of the chips. Assuming that you have really good contacts from the battery (you can solder to these temporarily to make sure that you do have good contact) it might that you have a partially corroded trace. Or, as you said, a component that's failing. Or it could be just a single bad solder joint. You can re-solder all the connections for starters, that's easy enough to try.