Can anyone ID these old cabinets?

On 03/28/2014 12:21 PM, Jules Richardson wrote: A lot of projector heads were made during the 1930s and still in service in the 70s and 80s. They were incredibly rugged. RCA serviced most of them, regardless of make. All projection setups to my knowledge were at least 2 projectors--on the high-volume setups, you could have 3 or 4, reserved as backups. I'm trying to remember, but I think the lamps I used were Ashcraft Super-Cores, running between 95-105 amps on about 50-60VDC. Water-cooled carbon holders with a rotating anode to keep the wear even. DC supply was by a 40hp MG set in its own fire-safe room (concrete block). Ballast resistors were mounted in cages attached to the walls (the MG set had to be able not only to supply current for the initial arc strike, but also had to have enough reserve to power two arcs during changeovers without the one in use dimming). Sound pickup was via simple phototube (not PM). Switching sound between projectors was accomplished by keeping the inactive exciter lamp at a dull red glow and then switching lamps, rather than audio at changeover. The drill for a changeover went something like this: Thread the second projector so that the "7" was framed in the gate. Wait for the "reel almost empty bell" on the active projector and strike the arc on the second projector. Wait for the first set of changeover dots on the screen, start the motor on the second projector. When the second set of dots showed, pull the lamp dowser (an asbestos gate behind the (water cooled) film gate and kick the changeover pedal. Go back to sleep. It all seems to be horribly imprecise, but it did work. --Chuck