Star Trek: The Next Generation
Williams, 1993The right cannon slowed to a crawl. I took everything mechanical apart and cleaned it- zero difference. When I put it back together and fired it up, something smoked. Measuring voltage, I get zero volts on transistor base of Q40. Any advise to what to check is appreciated! Everything else seems to work fine.
Brad
This same thing happened to me about a year ago. I had to replace the gun motor and the short white arm crank that attached to it. You can buy the parts from Marco. You can try other places and see if it's cheaper.
http://www.marcospecialties.com/pinball-parts/03-8619
http://www.marcospecialties.com/pinball-parts/A-17562
You will need basic tools and pin punch and replacement pin. I forgot the size of the pin but you can measure it with the pin punch.
Good luck
Good luck
Thanks! To give a little more detail - the cannon works fine with 12v applied. Measuring the volts across the motor - zero volts. Measuring the voltage at the base of Q40 - zero volts. Grounding the tab - nothing... I checked the transistor, it's fine. I also checked the drive transistor for voltage and shorts, it's also good. So, what powers the base of Q40 for 12 volts?
Thanks!
Good question. I'm not sure. You should post this on the Star Trek forum section. I agree with you this sounds like a board issue.
Have you checked the Motor EMI board? You said that something smoked, have you found any sign of what that was, should be visible evidence of whatever got hot enough to burn?
Quoted from NoTellin:So, what powers the base of Q40 for 12 volts?
Ok, it took me awhile to figure out what you are talking about but I think you are referring to the metal tab (collector) of Q40. If my assumption is right, the 12V you should see there when the motor is off comes from J118-2 of the power driver board, to J1-3 of the the motor EMI board, to J2-1 of the motor EMI board, through the winding of the motor, back through the EMI board an on to J126-2 of the power driver board, finally arriving at the collector of transistor Q40.
Of course if the motor is commanded on, or Q40 is shorted, you should have 0 volts there.
Thank you Pin_Guy. I found the diode on the right EMI board was fried. I replaced it and I'm back to my original problem. Progress 
The gun works but is very slow when the gun opto's are blocked, normal when not. It's not the weight of the ball or jammed grease on the shaft. A) I started by cleaning the whole assembly and B) when the opto's are open (game fires up - no ball) I measure 9.5 volts. When I block the optos with my finger (not touching anything) I measure 3.4 volts across the motor. I'm not seeing how the LED opto's affect the 12 volts across the motor but I'm wondering if the cathode side isn't making ground or something. Any direction is appreciated!! Anybody have this issue before?
Thanks!!!
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