T2 / Revolution X - Restoring the Gun(s). *Warning - Lots of detail!

braedel

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I recently picked up a nice T2 Judgement Day (Williams/Midway) machine. Everything on the game was great but the guns needed some work. I'm documenting here with the hope some others will benefit, and I may need some help or some shared wisdom along the way!

Here were the issues prior to tearing down:
  • Both dust washers missing
  • What sounds like coins/tokens moving around inside the gun base enclosures when moving
  • Red LED on P1 Gun not working
  • Triggers sloppy and require a lot of effort to actuate
  • Screen tracking of guns is very sloppy with dead spots (hysteresis) and non-linearity
  • Recoil on P2 gun does not work at all
Some photos:
Just after delivery and powering up.
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Everything appears to be there with the exception of a few black screws.
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Underside: Shows mounting and wire routing
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How Up/Down arc is mechanically amplified to rotate potentiometer (more on this below)
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Left/Right movement is converted here through the same arrangment
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Inside gun:
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Trigger Switch Information:
Manufacturer: Omron
PN: SS-01GL2T
  • SS = Subminiature Security
  • 01 = 30vdc @ .1 amp
  • GL2 = Hinge Roller Lever Actuator
  • T = Quick Connect Terminals (even though they soldered in lieu of using a spade terminal)

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I was able to source some new ones on eBay (I actually bought 20 of them if someone is in need...) The only difference is my have solder terminals (as they were soldered anyway...)
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....more to come (that's what she said)
 
The potentiometers have seen years of use and probably worth replacing since I'm in here. Sourcing the original parts is possible, but they are rather expensive. I decided to look at the specs and see if an alternative could be had...

*Note: Both Pots are the same part number (4 total per game)
Manufacturer: ETI Systems
Value: 5K Ohms
Tolerance: 10%
Type: Linear
Linearity accuracy: 1%
Rotational Life: 10,000,000 - That's a lot of rotations!
Electrical Angle: 320º *This is a lot compared to many other devices out there - I needed to verify if this spec was necessary
Shaft Diameter (that's what she said): 1/4" (.25")
Shaft end: 'D' type or Flatted

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I wanted to verify the total rotation, So I moved both X and Y axis to each end point, marked, then measured.(I will remove sharpie ink before completion!)
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Using a protractor, I measured the angle, then subtracted from 360. The result: Worse case, 250º! (So the 320 they sourced caused lost resolution)
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How they are configured: Each potentiometer has a fixed +5vdc and Ground present at pins 1 and 3. Pin2 ('The Wiper') provides the feedback to the AtoD Converter. It will sweep between 0 and 5 volts depending on position. Keep in mind, to get the full 0 and 5 volts out, you have to exercise the potentiometer through it's full range (320º in this case). Since the mechanical rotation is limited to ~240º, we are losing resolution)
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Gun board Inputs:
U2 = ADC0844
This IC has 4 multiplexed Analog to Digital Converters with only 8 bits of resolution (256).
This means as you move each axis of the gun (X or Y), the value that the game code evaluates changes from 0 to 255 (0 to 5vdc)
Full Left to Full Right On Screen: 0 to 255 steps (19mv/step)
Full Up to Full Down on Screen: 0 to 255 steps (19mv/step)
Since our Potentiometer was designed to provide 0 to 5 volts with 320º of rotation and we are only using ~250º.
This means we are leaving a lot of those steps unused which during the calibration leads to bigger step sizes as you move.

*Since these potentiometers are only being used as a voltage divider, the actual value of the unit is not that critical. You could probably use anything from a 2.5K to a 20k without issue. (5K is a best practice many people use.)

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This is what I ordered to try out (will report back, but am hopeful)
Manufacturer: TOCOS
Value: 5K Ohms (Same)
Tolerance: 10% (Same)
Type: Linear
Linearity: 3% Max (Less, but question original)
Rotational Life: 2,000,000 (Less, but this is probably 30 years!)
Electrical Angle: 280º - THIS IS Much BETTER! (Still has 300º of mechanical travel) *May need to spend a little more time getting it adjusted to start
The mounting and shaft specs appear to be similar/same


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~Brad
 

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I found both the dust washers broken up inside the steel gun enclosures. I was able to measure, model in CAD and 3D print new ones.

Original Dust Washer (this was the best one)
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CAD Rendering of Model:
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3D Printed Part (next to original) ready to use!
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The new pair ready to go!
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~Brad
 
The guns were missing a few of the smaller screws (8 per gun). They are 8-32 x 3/8 Countersunk. The original are 'security/anti-tamper', but I just went with the allen. There are still a bunch of security screws there.. I ordered 100 from eBay (if anyone is in need).

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~Brad
 
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