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Star Trek Next Generation technical help please.

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  • Star Trek Next Generation technical help please.

    Hi everyone

    I have a friend whose STNG cannon launchers kept moving after boot up. The test report showed 'LT LAUNCHER CAN'T FIND HOME ERROR'. Also RT LAUNCHER etc.

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    The CPU board looked good (no corrosion) so I reseated all the cables on the CPU board with power off. No change upon boot up.

    Once in 'Switch Edges test', I manually triggered the microswitches underneath the cannon launchers but they both failed to register.
    These microswitch levers are triggered by the cams underneath the cannons.

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    I didn't have a manual with me but I decided to change both microswitches even though there was slim chance of both failing at the same time.
    Once again the cannons keep searching for home and the new microswitches still didn't register in Switch Edges test.
    The old microswitches tested ok out of circuit.

    I had a known good CPU board so I fitted it and hey presto, no more faults.

    Once I got home, I looked at a STNG manual and a quick look at the switch matrix shows all the cannon launcher switches in column 9.
    I discovered that each launcher has two microswitches underneath, one MARK and one HOME

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    Column 9 appears to be sensed by the 8 bit driver board but it was fixed by a CPU board replacement.
    How do I progress from here?

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  • #2
    I'm pretty sure those switches only register in the specific cannon test.
    Is the ribbon cable attached to j204 and the right way around?

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    • #3
      The owner wouldn't have opened the back box to mess around with the cables, he's not technical. It was definitely fixed by changing the CPU board so that's where i suspect the fault is. I could fit it to another wide body with the 8 bit driver board, Twilight Zone and see what happens.

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      • #4
        Looking at the diagrams, the home and mark switches go via the 8 Driver Board to the CPU on J204. Since all of column 9 is not registering look at U7 pin 9 74LS244 on CPU board which is data line D7 to the 8 Driver board.

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        • #5
          Originally posted by c_mario View Post
          Looking at the diagrams, the home and mark switches go via the 8 Driver Board to the CPU on J204. Since all of column 9 is not registering look at U7 pin 9 74LS244 on CPU board which is data line D7 to the 8 Driver board.
          Thanks a bunch, I'll just change U7 and stick it back in his game. I'll report back in about a week.

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          • #6
            I know it's been months but the owner went overseas so I couldn't go over until yesterday. With U7 replaced, the fault was fixed (the cannons operated normally).
            Thanks for your suggestion [MENTION=12635]c_mario[/MENTION] !

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            • #7
              its possible looms are rubbing in cannon and took out chip
              Australian Distributors for Planetary Pinball, Chicago Gaming, American Pinball.
              Your one Stop Shop For New Pinball & Arcade Games.

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