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Light Gun


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Yeah, no problem. I just remapped the pins using this info :




SMS Pin 7 (Light sensor) to Vectrex Pin 4 (Button 4)
SMS Pin 6 (Trigger) to Vectrex Pin 3 (Button 3)
SMS Pin 5 (VCC) to Vectrex Pin 7 (VCC)
SMS Pin 8 (GND) to Vectrex Pin 8 (GND)

I'm developing games using this pinout. Of course this still requires you to press buttons on the controller in port 1 for the original Vectrex lightpen releases but it'd be simple to make an adapter with 2 db9 plugs for use with those games. I chose pin 3 for trigger so we could make an adapter with passthrough for Atarivox (which uses pins 1 and 2 to communicate) or Atari driving controller.


I'll be selling a lightgun game pack and lightgun adapter cables soon. Keep an eye on my website.


Here's a short preview of another lightgun compatible game I'm working on.

Edited by KidQuaalude
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  • 2 years later...

I'll post this info eventually as a web page with photos. Please comment if you see any mistakes or parts that could be improved.


Rather than reinvent the wheel, I started this with the info from Chris 'Binarystar' Malcolm's project from 2016.

He posted:
SMS Pin 5 (VCC) to Vectrex Pin 7 (VCC)
SMS Pin 6 (Trigger) to Vectrex Pin 3 (Button 3)
SMS Pin 7 (Light sensor) to Vectrex Pin 4 (Button 4)
SMS Pin 8 (GND) to Vectrex Pin 8 (GND)
That's all the info we need to work out how to rewire the Light Phaser with a new cable taken from a Sega extension cable.
Take the Lightgun and carefully split apart the two halves of the rubber shield around the Sega plug. You'll find the inner part
of the plug encased in a translucent white plastic. However if you look at it carefully you will be able to see the wires inside...
Examine the cable and correlate the wiring colours to the pins in this diagram:
Light Phaser plug:
5 4 3 2 1
\ * o o o o /
\ / (looking from the mating side into the holes.)
\ o * * * /
9 8 7 6
SMS Pin 5 (VCC/+5V)
SMS Pin 6 (Trigger)
SMS Pin 7 (Light sensor)
SMS Pin 8 (GND/0V)
In my Light Phaser they were:
SMS 5: green (VCC/+5V) .......................
SMS 6: blue (trigger) .......................
SMS 7: grey (light sensor) .......................
SMS 8: black (GND/0V) .......................
(If your wires are different colours, write them in here and in the diagrams below where there are "......"s.)
Now it's time to open up the Light Phaser - there are obvious screws all on one side, plus one hidden screw under the logo. Ten seconds under a hairdryer will
loosen the logo decal enough to slide a fingernail under one end and partially bend it back enough to undo the screw below it.
There's a lens that may fall out at the front - this is a good time to give it a clean (and the rest of the unit if it needs it).
Looking inside the Light Phaser we see the logic PCB with wires coming out one end:
............. o | black (GND)
............. o | blue (trigger)
............. o | green (VCC/+5v)
............. o | grey (light sensor)
(Ignore the two red wires running to the micro switch. Leave them attached.)
Now take a SEGA extension cable. You might want to file down the corners of the plug at this point and confirm it can plug in to your Vectrex.
Put your joystick/control panel on the other end and test that it still works, to confirm that you can insert the new plug far enough to make contact.
Cut the extension cable about a foot from the socket end (male pins - the end where you attached your joystick to test).
Strip off about an inch of covering and expose the 9 wires.
Use your continuity tester to correlate the wire colours at the cut end to the pins in the plug end (female)
(You'll probably have to push some narrower pins or solid wires into the plug holes to make contact as your voltmeter probes will likely be too thick)
We are only interested in 4 wires but you may have to test all 9 to work out the colour mapping, unless
it happens to be the same as my cable:
Vectrex Pin 3 (Button 3 for trigger)
Vectrex Pin 4 (Button 4 for light sensor)
Vectrex Pin 7 (VCC/+5V)
Vectrex Pin 8 (GND/0V)
Vectrex plug:
5 4 3 2 1
\ o * * o o /
\ / (looking from the mating side into the holes.)
\ o * * o /
9 8 7 6
In my case they were as below. Write in your colour mapping if different...
V1: red
V2: black
V3: grey (trigger) _________________________ (write in your colours where there are '______'s below)
V4: orange (light sensor) _________________________
V5: brown
V6: green
V7: white (+5v) __________________________
V8: blue (gnd) __________________________
V9: yellow
Taking these colours to the corresponding pins on the PCB:
PCB Original cable New Cable to Vectrex
------------------+ +---
........... o | -- blue (gnd) ------------- X ---------------| black ___________________________________ (write in your colours)
........... o | -- grey (trigger) --------- X ---------------| blue ___________________________________
........... o | -- white (+5v) ------------ X ---------------| green ___________________________________
........... o | -- orange (light sensor) -- X ---------------| grey ___________________________________
------------------+ +---
You might as well cut off the 5 unused wires from the new cable. (Take care that the cut ends can't short to each other - I staggered my cuts by a millimeter so they're not adjacent)
Now connect the two sets of wires at the X using the press-fit connectors. Test the light gun innards with your vectrex before reassembly.
(OR desolder the 4 wires from the PCB and solder the 4 wires from the vectrex in the holes, then test again.)
Fit the micro switch back on its columns.
Run the new wire round the screw posts which will give it a bit of resistance against being pulled out.
Put the lens and the end cap back in place and join the two halves of the gun back together, and screw together.
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  • 3 months later...

But how can a sms lightgun work on a vectrex?? Because a master system works with raster graphics while a vectror graphics , and so a sms needs a raster graphics display while the vectrex has its own vector display, so i wonder how that works, unless the vectrex crt screen works the same way as a raster display.


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