A couple of days ago one of my regulars (a 12 year old golden age video game connoisseur) let me know the Cheyenne gun was not working. I had this issue before, and thought it was going to be a pretty routine repair. In some ways it was, but just not the routine I knew.
Cheyenne
I tried checking all the wires connecting the gun to the Exidy 440 FPGA board, but everything checked out. Next step was to check out the game diagnostics, and ChatGPT was useless on this kind of niche repair, so I went to the source of truth, the 1985 manual. In particular, there’s a bit on the optical sensitivity adjustment which is connected to the PCB board that controls the light gun.
The part that really helped was the 1980s manual drawings trying to demonstrate what the diagnostic screen for “Optical Sensitivity Adjustments” might look like. The drawing in figure 6A is actually trying to show a waving series of lines, and the rectangular space where the light gun is pointed on top of that ( I have a video below demonstrating what that looks like):
Here is the video of what the optical sensitivity adjustments looks like for figure 6A:
The light gun PCB has a potentiometer that you can adjust once you see these yellow/brown lines.
What the actual optical alignment screen looks like from figure 6 of the manual
You need to remove the barrel of the shotgun to access the board.
Cheyenne gun without casing to get access to the PCB potentiometer
Once you remove that you can access the potentiometer for the light gun to align things correctly—you move things clockwise until the wavering lines disappear. After that, for good measure, turn the pot another quarter of a turn clockwise and the light should be good to go.
Small screw head is linked to the PCB board and adjusts optical light sensitivity
The last piece is going to the “Gun Sight Alignment” diagnostic tool and align the gun’s shot by shooting in the middle of the sight.
Gun Sight Alignment directions from Cheyenne manual
Anyway, just more fodder for the bavacade category of the blog to make finding this fix that much easier next time when I totally forget what it is I did this time.
This is also rad.