The lobes on the rotary cam encode the lookup table of which contacts should be open or closed in each rotational position of the shaft, which is typically rotated by a knob on the front panel of the instrument. A benefit of this design is low parasitics compared to traditional rotary wafer switches.
For cleaning, Tek recommends swiping paper soaked in isopropyl alcohol between the contacts and pads.
- 040-0541-00: Cam switch repair kit (1970)
- TekScope Vol. 9 No. 1, 1977 p.14: Cam switch cleaning tips