I have a HP75C which is malfunctioning. With battery removed for some hours, I press ATTN and then insert a fully charged battery. After this I press ATTN once again, the Time Setting Line appears on the display. I can also set the time and go to EDIT mode. After a while the calculator either hangs up or turns-off. Before it hangs I can run a program by reading from the card reader. Trying to reset according to manual does not help. Does anyone has a clue how to solve this problem? Does anyone have a copy of the service manual? I would very much appreciate. Thanks. Prabhu


Dear Prabhu,

maybe Tony Duell has more info on this machine.

Another related link could be http://www.series80.org/ ,

since the HP-75C uses a similar CPU as some

(if not all) of the Series 80 desktop computers.

Best Regards


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