(Topic ID: 59612)

Star Trek Next Generation odd problem? Any help welcome.

By Muppet_Man

6 years ago

Topic Stats

  • 16 posts
  • 12 Pinsiders participating
  • Latest reply 6 years ago by Muppet_Man
  • Topic is favorited by 1 Pinsider


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#1 6 years ago

Just turned on my STTNG and the canons just kept cycling round and round until they faulted out. Went into test mod, they test fine for switch activation showing closed and closed when reaching the park position and showing open and open when moving off.
Also found that if you press play button, it will pop all of the balls into the launch area, crowding them up on top of each other. Again, go into test function, check all trough switches and ball launch switch, all working perfectly. Drop a ball down the hole, and watch them all get switched as the ball passes.

Checked all ribbon connections, as have encountered that before. All seem ok, plus the tests work perfectly.

Any clues most welcome.

#2 6 years ago

I personally can't provide any advice, however I know this guy had a similar issue:


It was bad transistors for him. However the difference is that he was having some switches test bad, while you are not.

#3 6 years ago

Were the cannons trying to fire during the cycles? Optos on STTNG can cause some strange issues, I would start by going into switch test mode and and see if the cannon optos are working correctly. if they are, then I would continue to check all optos, starting with the trough.

Also leave it in switch test mode for a couple minutes and see if you have a switch(opto) going off by itself, could be dirty or have an intermittent connection. STTNG is very touchy with optos, if one is failing it can cause many issues.

#4 6 years ago

when was the last time you replaced your cannon wiring loom?
If never; suspect you need a new wireing harness.

#5 6 years ago

My guess is the wiring looms but, it’s strange that they would go out at the same time. Typically the left side goes out first.

#6 6 years ago

Agree with the wiring looms. I had some similar problems and was able to repair the wiring..but a new loom would have been easier.

#7 6 years ago

I too repaired the looms... with solder and heatshrink; but it only lasted a year or two at best in home use. The only "right" way to fix it is with new wire and new crimps or a new harness.

#8 6 years ago

Is the cause of the harnesses going bad simply the mechanical stress of rotating slightly for years / internal fraying of the strands? I don't have a ST:TNG but I wondered about this.

#9 6 years ago

Correct, the wires stress and break internally, the upgraded looms work great.

#10 6 years ago

Thanks for all the suggestions. Here's the results.

Opto's checked in canons and trough (replaced with Great Lakes mod a year ago) with camera (to see them working) and with switch test and finally with good old fashion finger in the front of them test and all working fine. There doesn't appear to be any opto's self firing over a five minute period.

Looms checked with test meter and visually for shorts and continuity and all perfect (were replaced around nine months ago).

Canons don't fire whilst turning.

Thanks for the link Daley, I haven't had a chance to read through that yet. I'll look tonight when I get home.

Cheers all.

#11 6 years ago

I had a signal problem with my STTNG and thought it was a defective opto circuit. It turned out that the circuit was operating intermittently, due to a bad pin on the CPU where the molex connector plugs to the board. I cleaned the pin and inspected the connector and it works fine now.

#12 6 years ago

Take the cannon cover off of both cannons. Any loose wires or two things that look to be shorting together?

Also you can go into options and disable both cannons. With this being true can you start a game or cycle problem still exists?

#13 6 years ago

Did you check the mark and home switches under the playfield? I had similar issues with my left cannon and the tab on the home switch was cracked so it did not register every time.

Would be odd for both sides to have a broken switch, but maybe a bad wire since they share a column in the switch matrix.

Good luck.

#14 6 years ago

there is a drop target that will stick from time to time at the top of the playfield. remove the glass and make sure its not sticking.

i had this mystery problem and fixing this fixed my problem. good luck.

#15 6 years ago

Are both the subway diverters working? When the balls are kicked out at the start of a game, where do they end up and are they getting kicked out anywhere?

#16 6 years ago

Thanks everyone for the suggestions.

It turned out to be a bad pin contact at connector J3 on the opto PCB under the playfield. The pin was loose and was not making a connection causing the mayhem. Took a while to find, but soldered up now so hopefully shouldn't happen again.

Cheers all.

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