I have a problem with the left cannon not being able to fire soon enough to make the center hole. It was working fine and then just stopped being able to shoot soon enough, but will fire soon enough to hit the beta ramp.

I had a similar issue with the right cannon and it took installing a new wiring loom and coil to get it working right again. So I installed all new wiring, a new coil, and it still has the same issue!

I've played around with the mark switch to make sure it's activating at the right time, and it is when I have it in test mode. I even adjusted the mark switch so it stays open all the time and still I cannot shoot soon enough.

I went as far as changing the diode on the mark switch because I was at the end of my rope. Can anyone help me with this? I really don't think it's the mark switch being faulty either. Frustrating!!! Thanks.
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*Edit: Solved! But read through if this isn't your problem, you might find other useful information by others that helped me work on this issue. Here's what it was:

The Home switch would open when the cannon started turning, then very soon after that the mark switch would open according to the LT LAUNCHER test 14. I adjusted the home switch to be open sooner in the turn, and the mark switch a little later in the turn which gave some extra time between the two switches opening. This did the trick and it fires when it should now... Every single time, reliably! Man it's nice to have that one sorted out!

In my attempts to have the Mark switch open sooner I had them opening too close together and I guess the CPU couldn't handle that or something.

I've messed around with it and it's driving me crazy! It doesn't seem to matter where the Mark switch opens and closes, it doesn't fire till past a certain point, which is too far to hit the first scoop.

I can wait until the cannon goes all the way to the end and hit the center scoop on the way back, but that's not how it should be.

Any help is greatly appreciated. I've been through all the posts about the cannons and I've tried everything that everyone else has done (that I know of). Like I said it was working amazingly well and just degraded to not shooting at the start of the swing, I hadn't changed anything to make it do that.

I want to think it's something wrong with the mark switch, but it registers fine in test mode.

I’m testing the switch in the cannon test that shows when mark and home switches are open and closed. Test 14 Lt launcher.

I can have the mark switch set to open as soon as the cannon leaves home but it doesn’t help.

Ok thanks, tried that and it hasn’t fixed it.

I was getting so good at nailing that shot off the left cannon at the start of the borg multiball too, 3 in a row a few times.

Any further thoughts? I’m trying to get this machine back to the Air Force base this weekend and this is my last hurdle.

I’ve just read more about the launcher test 14 and that you can hit the enter button to fire the cannon at any point in its travel (with the coin door closed of course). It’s firing at all points through its turn so I’m doubting it’s a break in the new wiring I installed.
What is slowing down the cannon from firing after the mark switch is open? An open switch means it should fire right? And it does but not till it’s good and ready lol.
Soooo frustrating, my little brain aches.

Thanks for the input. The optos tested fine in all positions of the cannons swing, so I think they’re working.
All the chips are firmly seated.

The home and mark switches are registering where they should. I can fire my right cannon not long after it leaves the gate but the mark switch on it isn’t setup nearly as tight as my left cannon mark switch. It’s almost as if the switches are somewhat irrelevant.
It’s driving me nuts being able to shoot just after the centre scoop.

Thanks very much for the input, it's much appreciated. I've put all new wiring into the cannon, including the optos, coil and lamp. It's having the same exact issue after redoing the wiring that it did before so I don't believe that's the issue.

I've moved the cannon in launcher test mode and left it in various places to go back to switch test and see if the optos are registering, and they do at every point in the cannons movement.

This sounds just like a wiring issue I know but I just can't believe it with what I've seen and tested. I may get desperate and redo the wiring again but that's a ton of work when I don't believe it will change anything.

The cannon doesn't make the firing noises until the ball is actually able to be launched by the trigger, so it's not like it's trying to fire but can't... I've had that problem on the right cannon. I would pull the trigger and the game would make all the firing sounds and the light goes off but the cannon wouldn't fire. This is somehow a problem of the cannon not being allowed to fire until a certain point in the swing, which is just a tad too late to hit the middle scoop. It has to be something to do with the Mark switch, but what?

I will try the banging on the table tests to see what I can find out. Thanks!

Edit: I tried banging on the table in switch test and nothing registered.

Sorry I forgot to answer that. No I don't have any mods hooked up, it's all stock.

Ok thanks, I tried that but it didn’t move much from where it already was. Great suggestion though.

Ok tried that, no change.

I’ll try adjusting the home switch as you’ve suggested Pin Guy, possibly the only thing I haven’t tried.

It was worth a shot but didn’t work. I’m at my wits end with this thing, not sure what to try.
To recap, it was working fine then just stopped shooting early enough without me changing anything. Then I put new wiring in and it didn’t change. Then new coil and no change.
The mark switch is definitely open when it should be so why won’t it fire till later? Stumped.

Sorry, yes the home switch is doing what it should. The home switch opens before the mark switch when it’s pulling away, and closes after the mark switch on the way back.

I was going to mention the cannons at startup. I’ve heard that some games will activate and test fire both cannons at startup, and some only the right cannon at startup. This one used to be a right cannon only at startup and it ran fine. Now it’s running and firing both cannons at startup since I’ve worked on left cannon but I now have this issue with left side firing late.

Wow that sounds promising, thanks!

Ryan asked me to send videos of the cannons firing in a PM, and I wanted to share what's been happening on this thread.
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Can you send me videos of each cannon firing? For some reason I’m thinking when I fixed this, it was the motor controller PCB.
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Hi Ryan, thanks for helping. I’m going to post this on my thread as well.

So here's what happened when I turned on the game to video it for you. At power up the cannons both started turning as they have been now and fired like normal. Then I played a game in battle simulation mode to fire shots from the left and right cannons. It was firing like normal after a couple shots! I was able to shoot like I could before the problem started. Then I went for dinner, came back, turned the game on, and noticed only the right cannon went through the power up routine... like it did before this problem started!

So it seems like you might be right about the motor board, I’ll have to check it. I didn’t know there was one to be honest, I’m still learning this machine.

Nothing worse than a problem that comes and goes for no known reason. I need to figure it out or it will happen again for sure.
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Ian,

For some reason I’m thinking it was something simple like poor solder connections or a bad IDC connector. I’ve had 3 STTNGs over the years and I’ve repaired probably 15 others.

I’ve been to the office twice since I said I would check my notes and totally forgot to look them over. I stop by real quick and get started doing work stuff or playing whatever title we’ve just finished rebuilding and I sometimes lose focus. I’ll check ASAP.

Anyways, it’s worth checking the motor drive PCB and connectors. If that’s not the culprit, it’s at least preventive maintenance.

Another thought, clear the balls, raise the playfield and run the cannon test. Make sure the cannons are in time, meaning do the switches open and close when they’re supposed to. It’s been a while since I’ve worked on one, but it seems like one of the switches could be good and look like it’s operating correctly, but close when it should be open, meaning the cannon won’t fire because the game thinks the cannon is “home”.

Also, on the motor PCB, if you take it off, replace the 1N4007. They’re cheap. It’s quick and easy. If one of the leads is slightly cracked, or the diode “leaks” the gun isn’t traveling quite as fast as the other, which again, the CPU could have a closed switch false “home”
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Thanks again Ryan! I took the motor pcb off this morning and reflowed the solder on the connectors. The diode looked very healthy and I don't have one on hand so I just touched up the solder on it as well for now. When I started the game things worked as normal with only the right cannon going through the startup routine. Hopefully the connectors on the motor pcb were the problem and hopefully this fixed it. I will play the crap out of it again this week and report back my findings. In the meantime I'll order in some 4007 diodes and touch up the solder on the other motor pcb.

OH, and also, the switches do register open and closed properly when they're supposed to.

Thanks for all the help, I hope we're done here!

Update today. Still firing well, but at power up both cannons are running through their tests again instead of just the right cannon. It’s odd that they’ll go for a while with both rotating at startup then switch back to one at startup. But I’ll see how long it keeps working, I think something might still be wrong with it.

Still working as of today, although there is the odd time it doesn't seem to want to fire soon enough. I would say it's shooting 95% at least, and maybe I just pulled the trigger too early when testing... so more testing this week. I have a feeling that there's still something not quite right.

I think the home switch is set ok on it. It's not set very tight so it should always be reading as home when it's docked and the game starts up. This is going by the launcher test 14 which shows very clearly what the switches are doing and when.

It's definitely not working 100% yet, and the left cannon will not always fire soon enough. The right cannon home and mark switches seem to open later than the left side but the right cannon will fire the second it leaves home. That's too soon, but I'd rather have that than fire too late like the left.

I'm going to end up running new wires up to the coil again, it's the only thing I can think is that there is a break in the new wire I put in. It's a lot of work but I'll do it as a last resort.

Stay safe fellow pinball nuts. I'll post again whether I fix it or not.

That is a great idea, thanks Pin Guy! I should be able to see if there is any interruption in the connection this way.

I hooked up my dmm to the coil connector and it kept its connection through the cannon turning, and I ran it for a while to make sure. I also hooked it up to the home and mark switches to make sure they were actually activating when the tests said they were. All good.

So! What the heck? The mark switch is clearly open as soon as the cannon leaves home. The cannon is once again firing late most of the time. The right cannons mark switch opens much later yet I can fire it as soon as it leaves home, maybe sooner I don’t know and I’m afraid to try.

Photo shows where cannon is when it should fire but doesn’t till well after.

Why do I always get these weird ass problems that are probably simple but elusive?

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Ok I may have it fixed. I noticed the home switch and mark switch were opening very closely to each other, unlike how the right side cannon's switches are setup. So I adjusted the home switch to be closed for less time, and adjusted the mark switch to open a tad later. It seems like this extra time between Home and Mark switch opening may have straightened things out!

So far so good and I'll post back when I'm certain it's fixed this time. All things considered, it's been a good day. Thanks for everyone's input!

And it was simple... I knew it had to be something with the switches. So it's 100% solved and I'm certain what the problem was as I stated above.

The Home switch would open as the cannon started turning, then very soon after the mark switch would open according to the LT LAUNCHER test. I set the home switch to be open sooner in the turn, and the mark switch a little later in the turn which gave some extra time between the two switches opening. This did the trick and it fires when it should now... Every single time, reliably! Man it's nice to have that one sorted out!

Absolutely! It's all for the betterment of everyone trying to keep these machines going, and I really appreciate all the help that is always offered here.