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STTNG Strange Issues

T-1000

New Member
Feb 5, 2021
10
5
3
Kingston Ontario
So I am getting really annoyed with my Star Trek Next Generation. I am having weird issues where it forgets the balls completely. You can play a couple games and it can be fine then all of a sudden a ball drains and it doesn't see it then goes through the ball check a couple times and you get a ball back then after that somtimes it will see it drain, somtimes not. I had a game today (after all fixes listed below) where it just kept doing it and would not see a ball drain open coin door and trough board is working perfectly fine I had to reset the machine then fine. It's like the cpu gets stuck in some loop where it's not paying attention to the balls. It also somtimes gives me extra balls for no apparent reason not when in a mode where it should. I know this machine is notorious for opto issues I have checked over wiring for basic stuff couldn't find anything, checked subway to make sure nothing loose or out of place. I figured sense I plan on keeping the machine for a long time just replace the 16 opto board and the opto trough
boards knowing they can be problematic. I have also soldered the power wires directly to the trough board to eliminate possibility of a bad connection there. Then I figured it could be the 12v power feeding it so changed the bridge rectifier and cap on the power supply board. I did find one diode on the bridge rectifier was bad. Still same issues. Other thing it will do is somtimes the wrong music will play in modes or be slow changing over to correct music. I am starting to think the cpu board has a issue. It currently has a Rottondog cpu board in it. I am also running a Dino color display but I have the same issue if I switch back to the regular dmd. Just hoping someone else might have a idea or seen this before.
 

MrMikeman

Well-Known Member
Nov 25, 2019
792
641
93
Ottawa
The optos at the 3 VUKs could be problematic as well. Each VUK has more than 1 set of optos.

Both gun VUKs have 2 sets and the other VUK that kicks the ball out to the left flipper has 4 sets of optos. They all need to be checked/tested.
 

T-1000

New Member
Feb 5, 2021
10
5
3
Kingston Ontario
Sorry maybe I didn't word it right I have replaced the 16 opto board and trough boards with new ones. MrMikeman other then in switch test is there any other test for the vuk optos? They all work in switch test or at least when I try them.
 

MrMikeman

Well-Known Member
Nov 25, 2019
792
641
93
Ottawa
Sorry maybe I didn't word it right I have replaced the 16 opto board and trough boards with new ones. MrMikeman other then in switch test is there any other test for the vuk optos? They all work in switch test or at least when I try them.
Switch test is good enough but you need to lift the playfield to test all of them. Also light shaking/pounding with your fist on the playfield while in switch test may identify intermittent ones.
 
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