HP 9100B not functioning after shipping. Suggestions welcome

Dave dfnr2 at yahoo.com
Sun Mar 1 22:51:07 CST 2015


I recently acquired an HP9100B which was working before shipping, but on arrival does not respond. The fuses are intact, and I can hear the power supply humming on power up, but there is no CRT output, and I cannot activate the error light (for example, by STOP-CLEAR-/ to get a divde by 0 error.) The register label backlight also doesn't light, but apparently did not light before shipping, when the calculator otherwise worked. 

I have Tony Duell's excellent schematics, which I'm grateful for. I also have a service manual, and plan to go through it, but it seems a bit short on theory and detail. I'm not in position to swap out boards.

I haven't been able to check it out in depth yet, but this week I will be able to spend some time on it.  I have, however, done some basic inspection, and reseated whatever boards are accessible without a screwdriver.  This didn't help anything.  I didn't hear any rattling from the CRT, but haven't yet pulled it out to inspect it.
My plan is to start out by checking the power supply voltages, clocks, and move on from there. However, since apparently something changed during shipping, I'd be interested in any suggestions that would help inform a smarter investigation. I am hopeful it's not the CRT, as I would expect a bad CRT to not interfere with the error light. 

Any suggestions or guidance would be very much appreciated. 

More information about the cctalk mailing list