(Topic ID: 171695)

Stellar Wars - Diagnostic switches not working

By NoQuarters

2 years ago

Topic Stats

  • 6 posts
  • 3 Pinsiders participating
  • Latest reply 2 years ago by dothedoo
  • Topic is favorited by 1 Pinsider


Linked Games

#1 2 years ago

Recently acquired a Williams Stellar Wars. Playing well. I thought I'd like to change from 3 ball to 5 ball game and set the game to free play. However I found that the Diagnostic Switches inside the coin door are not working.

Auto Up / Manual Down toggle switch, Advance button and High Score Reset buttons inside the coin door. They don't seem to respond to any input.

Any ideas why the Diagnostic switches are not functioning ?

#2 2 years ago

My Star Trek TNG is doing the same thing starting tonight. Must be some sort of pinvirus.. Any suggestions would be appreciated.

#3 2 years ago

I just got my Star Trek TNG fixed. The problem stemmed from one of the black ground wires breaking loose from the coin mechanism microswitch. These wires are easily torn loose because they hang from the bottom of the coin mech switches at the bottom of the coin door and are worked loose by opening and closing the door, especially if they rub against the coin receptacle. The diagnostic switches run off of the same ground supplied by the coin mech microswitches. Check those black wires. I bet you'll find a loose one. On mine there were two wires soldered to the same switch post and one of them had broken loose. Good luck!

#4 2 years ago

If it's not a wiring/connector issue (which it isn't if this is the one from Expo), check the 6821 (IC18) and associated 74LS02 (IC5) chips on the MPU.

2 months later
#5 2 years ago

Yes I did get this game at Expo. I'm not much of a Solid State mechanic other than fooling a little with some Gottlieb System 1.

Sorry for the delayed response. I have played the game 3 ball for quite a bit. Today being rather cold and having the day free I moved Stellar Wars out of my row of games for a look see.

After a little on line search I found where IC5 and IC18 are located on the MPU board. IC5 appears to be a soldered in connection and appears solid and fine. IC18 is sockected and seems to be very tight. I couldn't budge it from it's socket and didn't want to pry it. I did see that there was some cleaning done on the board at some time under the edge of IC18 socket on the right side. I would guess that a replacement socket was maybe installed at some point. All appears well to the eye.

#6 2 years ago

One or both of those chips need to be replaced. Since IC18 is socketed it would be easy to swap it with another one on the board and see if the problem goes away.

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