This is somewhat off-topic, but I'm setting out to make one working 7B53A from two damaged and dead ones. This actually shouldn't be too difficult as the damaged one just needs to have it's TIME/DIV switch assembly, and one slide switch replaced, and those don't seem to be damaged on the poor, corroded 7B53A that I'm already taking apart.
While taking the corroded 7B53A apart, however, I noticed that the push buttons (other than the single-sweep reset button) don't seem to have any illuminating lamps. They do, however, seem to be build to have lamps, both because the back end of the plunger is beveled to redirect light along the clear plunger, and because the button housing seems to have mount points for a light cage/baffle.
I've experimented with shining a laser pointer down the back of the back of the switch assembly, and the engaged pushbutton lights up quite beautifully. I expect that I could wire up and mount some LEDs at the top or bottom back of the switch assembly to illuminate the engaged buttons, and that half a dozen diodes will not be a significant current drain on the +5V rail, at least not compared to incandescent lamps.
Without the cage/baffle to keep the light from spilling all over the interior of the plug-in the transparent skirt on the TIME/DIV knob also illuminates in an especially subtle and pleasing way.
One 5mm LED is able to illuminate all four buttons in a column very nicely.
-- Jeff Dutky
