Manual for HP48 Classroom Display

[HP-Collection]

(07-10-2017 06:27 PM)Chris Dreher Wrote:  

(07-10-2017 06:16 PM)Joe Horn Wrote:  I vaguely remember (possibly correctly) that it controlled the position of the first scan line at power-up (not while turned on). If you have to always press the "vertical hold" button to position the screen correctly, then try twisting that knob and see if it changes the initial screen position (you'll have to power off and back on). After a few such adjustments, you should be able to have it power on correctly framed without needing to press the "vertical hold" button.

Thanks, I just tested it and that is exactly what the knob does. Cool.

Amusingly, I added my update about the florescent lights theory not working at the same time you posted what the actual purpose was. :-)

Aha, this is the same unit? What a nice thing: I do have a original packed unit with manual... here it is - with the explanation of the three knobs (the older unit has one slider instead of a knob).
By-the-way: InVision uses a display which is about 9x the size of the older unit.