Tektronix 1720 Vector Scope
Tektronix 1720
The Tektronix 1720 vectorscopes are available for 20-50 on eBay since most TV stations are decomissioning all of their analog NTSC gear. It is a cheaper alternative to the Vectrex for art projects or a compact MAME display, although the beam is not quite as sharp. Shipping is usually much expensive than the price of the scope, since it is typically a 19" rack mount combo with the 1730 waveform monitor.
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Games like Tempest and Lunar Lander are totally playable, although the smaller display makes the fonts very tiny. The voltage range in this case is -2.5 to +2.5 volts, which is just about the right vertical, but a bit low for the horizontal. This is using the output of the MPC4922 DAC directly, rather than going through my opamp circuit (which made things fuzzy).
It is a very deep tube due to using Electrostatic deflection (instead of magnetic deflection, like in the Vectrex). This makes it fast, but requires a very long tube to magnify the effect of the small deflection angles. It that would look great in an clear acrylic case, so I might re-house it. I'm not sure what to do with the 1730 at this point.
Wiring
The manual (PDF) for the vectorscope has a misprint on the XY input port pinout. Pins 7 and 5 are ±X while 3 and 1 are ± Y. You can run the inputs single ended by grounding the minus inputs and swinging the voltage ±5V.
For the Tek 1740A, the port is a DB25 and the pinout is in the manual:
| Pin | Function | Color |
|---|---|---|
| 2 | Ground | Red |
| 8 | Y+ | Gray |
| 9 | Y- | White |
| 10 | X+ | Black |
| 11 | X- | Pink |