My newly acquired HP19C seems to have died on me
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12-16-2014, 06:57 PM
Post: #7
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RE: My newly acquired HP19C seems to have died on me
(11-27-2014 06:47 PM)Katie Wasserman Wrote: The stuck-on problem would seem to indicate that the print head driver has at least one bad transistor in it. According to Tony Duell's schematic the 19C uses a single chip transistor array for this, not discrete parts. But it should be possible to bypass the bad transistor in the array with a single NPN. Hi Katie, 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. Cheers, Harald |
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Messages In This Thread |
My newly acquired HP19C seems to have died on me - Harald - 11-24-2014, 09:51 PM
RE: My newly acquired HP19C seems to have died on me - Harald - 11-27-2014, 06:28 PM
RE: My newly acquired HP19C seems to have died on me - Katie Wasserman - 11-27-2014, 06:47 PM
RE: My newly acquired HP19C seems to have died on me - Harald - 11-28-2014, 01:03 PM
RE: My newly acquired HP19C seems to have died on me - Harald - 12-16-2014 06:57 PM
RE: My newly acquired HP19C seems to have died on me - Katie Wasserman - 12-16-2014, 09:52 PM
RE: My newly acquired HP19C seems to have died on me - dct - 11-28-2014, 01:10 PM
RE: My newly acquired HP19C seems to have died on me - Harald - 11-29-2014, 11:04 PM
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