A mystery panel

DM160 diagnostic panel

A diagnostic panel perhaps from a 1ESS phone switch?
I don't recognize any of the legends.
There are no other tags, labels or nameplates.

I'd love to build a microcontroller circuit to make it run again for a permanent exhibit of Das Blinkenlights!


Front view
"INTERNAL PROGRAM"
SBSS BSL SBMS SBES FFW FFWA OMS OMSA OES OESA
CMRA CMRB CMRC CMRD CMRE CMRF
2 of the 18 are blank: no legend
DM160 closeup
This is probably the oldest wire wrapped item I've ever seen:
wire wrapped TUBE circuit in WOOD!
Rear view: 100K resistor for each grid.
All heaters and anodes are wired in parallel.
Such lovely workmanship on the wiring harness with lacing cord.
The DM160 indicator tube works similarly to magic eye tubes but it is only on or off: no moving pattern.
The DM160 was popular for a short while for transistorized digital circuits because the single tube is display AND amplifier.
A grid signal of 3v at 575 µA operated the display (not counting the 1.0 V filament and 50 V anode).
The appeal was how it is just one part,
compared to a high voltage transistor & neon bulb or a high current transistor & incadescent lamp.

For more information
  • r-type.org has tech info and animated images
  • radiomuseum.org notes how the DM160
    is identical to the 6977 and cv5412

    Bar indicator tube, specifically designed as indicator for transistorized computers.
    Blue-green bar lights when control grid is at zero potential.
    It is only on or off: no moving pattern like other magic eye tubes.

    50VDC at 0.5mA anode in on state;
    3VDC on the grid cut-off plate current and light.
    Filament Vf 1 Volts / If: 0.03 Ampere / -: Direct / -: Parallel, (AC/DC) /
    20,000 hours life. 4-pin flying leads base.