If you get the "Sorry, the file cannot be displayed. There seems to be a technical issue ..." error when trying to view an image, a workaround is to click on the cog icon in the upper right side of the media viewer, and then select "Disable Media Viewer". We are aware of the problem and are looking for a solution.
The Tektronix 531 is and oscilloscope that was made from the late 1950's through the early 1960's. I accepts on letter-series or 1-series vertical plug-in. There is also a rack-mount version, the Tektronix RM31A. The RM31A has a sliding chassis so that the scope can be serviced without removing it from a rack.