A test bench for HP thermal printing units (HP-82143, HP-82162, Topcat)

[Karl-Ludwig Butte]

After around 45 years, it should not be surprising if the paper transport in a thermal printer no longer works due to the rubber parts involved, which have now completely degenerated. The thermal printing unit from Hewlett-Packard is no exception; it was installed in the HP-82143A, HP-82162A and the desktop calculators of the Topcat family, such as the HP-97, from 1976 onwards.

This article describes a test bench with which the paper transport mechanism can be tested during reassembly of the printing unit after the rubber parts have been replaced, which would otherwise only be possible after completely reinstalling it in the printer or calculator housing.

The article is available in German and English.