There has been some discussion over the years as to how to disassemble the knobs for repair/cleaning. I got mine fully apart (thanks to the photos others uploaded when they got stuck) and uploaded photos.
For knobs designed like mine, the black cap pops off and there is a screw underneath. Until the screw is removed, the smaller knob cannot be separated from the larger.
The clipped off leads on the LED package allow testing each LED individually if desired; mine have a Vf of ~1.5v. Alternately, 7.5v across the array results in them just starting to glow.
The center pin on the left of the array (as oriented in close-up) is common. It seems the transistor on the lower left pin in the array is bad, as it doesn't respond to light; the others do.
Does anyone know where to find a 1x5 phototransistor array with spacing of ~1.175mm c-c?
The schematics don't show much beyond the fact that the array is biased with +/-15V, and nothing shown in the opto section of the 1982 common design parts catalog looks even remotely close.
Regards
Mark
