HP-19C Repair Odysee

[PANAMATIK]

The newPIK Prototype is complete and controls the printer motor!

Motor Video (16s 5.5MB) This is my first mp4 video in this forum. I hope you can play it in your browser. If not you can download the file.

I programmed the motor regulation for the HP-19C printer motor. The motor moves faster or slower when I turn the 50k Poti, clockwise is slower, counter clockwise is faster. I'm totally happy with it. Also the printhead pixels are driven and generate the Italic typeface like the original. I did not yet print on paper, because I need a hardware modification, because the STB signal must be anded to all 7 pixel signals. The duty cycle of the STB PWM signal is dependant on the battery voltage and the 200k Poti, and adjusts the printer intensity. I checked the printhead signals on oscilloscope. Timing is not critical. Keyboard buttons can be detected while printing, like in the original HP-19C.

This PIK firmware, when finished, should also work in the HP-97, but also needs the new ACT inserted. The challenge remains to make it compatible with the HP-97 and HP-19C with an original ACT inserted.

Next steps: Drawing the schematics, then designing the layout.

Bernhard