cranky HP95


I have an HP95 calculator which has lost it. As long as the machine is not asked to perform with the tape in operation everything is fine. The minute the tape is put into operation by sliding the trace switch to the middle or far right position, the display freezes with a negative entry and the tape does not either print or advance.

Can anyone help?

David C. du Four


Do you mean an HP95C? The really rare one?

I have repaired one (I don't own one, I hasten to add), and I have a reverse-engineered schematic (available, as ever, from HPCC).

My hope is that your problem is power-supply related. I assume you have a known-good battery pack in there (The 95C has the same protection circuit as the other topcats, but like other topcats, it only works when the machine is on. The 95C would therefore seem to suffer from the same RAM-killing problem as the 25C and 33C, etc). It might be something as simple as a dried-up capacitor

A worse possibility, of course, is ROM problems (if the printer driver code is screwed up, then the processor could go crazy when it tries to use the printer). The bad news is that these ROMs were only used in the95C, so finding replacements is impossible.

Possibly Related Threads...
Thread Author Replies Views Last Post
  cranky HP95 Dave du Four 0 218 02-19-2005, 07:50 PM
Last Post: Dave du Four
  Update on HP95-lx prototype Edwin Herdman 0 224 10-14-2002, 12:28 PM
Last Post: Edwin Herdman
  HP95 external power steve 0 196 08-28-2000, 08:04 PM
Last Post: Steve
  HP95/100/200 keypad steve 1 240 08-16-2000, 11:13 PM
Last Post: Andrés C. Rodríguez
  AC POLARITY HP95-LX erwin 4 434 07-27-2000, 04:17 PM
Last Post: Kevin FitzGerrell
  HP95-LX ????? erwin 11 827 05-11-2000, 08:16 AM
Last Post: Reinhard Hawel

Forum Jump: