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My newly acquired HP19C seems to have died on me
11-28-2014, 01:03 PM
Post: #4
RE: My newly acquired HP19C seems to have died on me
(11-27-2014 06:47 PM)Katie Wasserman Wrote:  I'm not an expert on the 19C, but I'm curious about what you said:
"found the paper arround the printer head had become all blue"

That can/will happen if the paper is exposed to heat or certain chemicals -- isopropyl alcohol for example. If you left the calculator on, perhaps something inside got very hot, was it plugged in to change the batteries? Maybe something failed in the charging circuit, maybe one or more of the cells in the battery pack are shorted.
It was the printer head that got hot of course. It is just how I discovered this had happened.

Quote: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.
Is that the RCA chip?

Unfortunately I don't have the schematics CD. I have been trying to get one for about half a year now as I am after an HP65 schematic as well. I got as far as sending the money, but then everything has gone quiet again. Looks like my mails end up in Dave Colvers spam folder.
Could you maybe email me the schematics? I think this should be OK, as I alreay payed for the CD.

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RE: My newly acquired HP19C seems to have died on me - Harald - 11-28-2014 01:03 PM

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