Have you replaced the cannon wiring harnesses yet? My TNG used to do something similar to what you describe. Worked fine in test mode, it only went wonky when the cannon was in certain positions. You can try to replicate the problems by moving the cannons to different positions, then going into test mode to see if you get phantom opto hits. If the game thinks there is a ball in the cannon it starts the Launch Probe sequence.

Replaced the harness and all was well.

If the game hasn't been maintained well I'd recommend a tear down of the cannons including:

1) Pulling the cannons completely apart and cleaning off the any old congealed grease on the shafts.
2) Replace the wiring harnesses on both cannons.
3) I also replaced the armatures, sleeves and springs.

Made a big difference.

Oh, and this can also be caused by a flaky connector on the trough opto boards if cleaning/resoldering the transmit board doesn't fix it. You could also consider ordering new trough opto boards from Great Lakes Modular.

I bought mine as a "shopped" machine as well. Unfortunately what shopped is can vary widely depending on who did it. Whether or not you need to clean the cannons is pretty simple to figure out. If they move pretty slow and make a lot of noise odds are you have a problem.

If cleaning and resoldering it do not work, you can buy a transmitter LED from radio shack..... I was happily stunned to find one there and have mine back up and running in no time. It's an easy fix. From what I've heard, since the transmit side is the active one, that's really the point of failure, versus the receiving side.

http://www.radioshack.com/product/index.jsp?productId=2062565

Enjoy your STTNG!

I am a noob myself, so am happy I could help out. Have fun, it is a great pin.

anyone know who has the new high flex harnesses for sale right now? Seem to be out of stock everywhere.

no suggestions?

"Thanks, I did buy it as a shopped machine, and everything looks pretty good (aside from those few issues I mentioned). I had it shipped from NJ to NE, so I figured most of what I've seen so far is as a result of that process."
hey bull, glad you could work it out. its a great game. interestingly i am getting a machine from omaha and shipping it to nj! have you ever had any dealings with "Central Distributing"?
and did you deal with a compnay in nj or private sale and shopping?

buldoggk - so where did you buy your harnesses?

Thanks,
RacerRik

I'm fairly new at this, although I did have access to a Jokerz! machine many years ago that I was able to tear apart and get a basic idea of how all these things come together. I just received my STTNG yesterday, and while I knew it was one of the more complex animals out there, holy smokes!
It's in really nice shape, and after fixing a few things that I assume happened during shipping (some loose bulbs, GI wires in the backbox, and a switch arm that popped off), I'm off to the races with three problems remaining.
The first is that a drained ball isn't always recognized. It seems that it's easily solved by cleaning/resoldering the transmit board on the trough. It doesn't happen often, so I'll save that for a rainy day. Worst comes to worst, I'll just replace it.
The second is the left flipper doesn't always register a tap, like when selecting the different ball start sequences or missions in Command Decision. That's also hit or miss, and I have a new opto on the way for that. I only mention these two things in case someone thinks I'm barking up the wrong tree.
The one that's perplexing me right now is that during anything that uses the cannons, the "Launch a Probe" sequence starts. On the Borg multiball, it starts after the first Borg shot. No ball ever gets into the launcher, but it lights up and the system won't release the third ball into multiball until I pull the trigger. Same problem during the Ferengi multiball.
Battle Sim is a little different. It lets me through everything, then at the end kicks off the Launch Probe (with no ball).
Even in the actual Launch a Probe sequence, it happens twice. The first time with a ball, then again while that ball is in play, but without a ball. If the ball drains, the game still thinks it's playing until I hit the trigger, at which point I think it realizes there was no ball and ends round.
All I know to do at this point is put the game into test mode and have the Test Switch Edges function on. When I put my finger or the ball in the slot, it works as it's supposed to. When something is blocking, it knows it, and when the optos can see each other it changes states.
Perhaps there's something in the subway that's messing with this? A switch or something? Are there hall effect or prox sensors on this?
I'm stumped, but in an excited way.
Just as an aside, on my third game I sent a ball up the Alpha Quadrant, heard a metal sound, then the ball came out pushing a switch lever. So I owned the game less than an hour and was already tearing it apart to put that flag back on. Welcome to pinball ownership, I guess
Thanks for your help!

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Glad you found Jim's. I bought the harnesses from him recently and thus fixed some bizarre, intermittent cannon problems. Everything works perfectly now.