Re: 7B92A time-base plug-in odd behaviour

Roger Evans

On my 7B92A, the microswitch near the front panel is connected by a single wire to P911 on the interface board. P911 is to be found on schematic <4>, 'Delaying Sweep', near the top right corner. It is marked as going to R334 on schematic <3> and the switch is marked as S490. S800 on 'Horizontal Logic', schematic <7> is marked with 'pull for alt, push for delay' and is surely the second switch on that shaft, it connects through to the Readout board.

I noticed while investigating my 7B92A that the whte plastic 'cotton reel' that activates the microswitch didn't seem to be an entirely tight fit on the shaft but settled down happily after a few iterations. I hadn't noticed any odd behaviour when it is operating in the mainframe.



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