(Topic ID: 259566)

STTNG Coil locked


By lemanp

10 days ago



Topic Stats

  • 19 posts
  • 4 Pinsiders participating
  • Latest reply 8 days ago by lemanp
  • Topic is favorited by 2 Pinsiders

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IMG_20200113_144420 (resized).jpg

#1 10 days ago

Hi there!

I've been trying to fix my STTNG for a couple of days now with no success, any help will be appreciated!

While playing (all was 100% functional), I started to get issues with balls not detected. At the same time I smelt what you never like to smell playing with an electronic device... Switched the STTNG off and opened it, F103 was blown and Solenoid 37 was burnt and locked, I replaced F103, S37 and the sleeve.

I restarded it and tried to test stuff, but realized F103 was blown again, I replaced it and started the STTNG again but playfield opened. As soon as powered up again S37 locked itself so I switched the pinball off immediatly to avoid further dammage. Then I looked here and over the web to check what else needed to be tested.

I found out that Driver and Pre-Driver needed to be verified, and saw that Q16 didn't show up good values on the tester, so I replaced it. The pre-driver in Q8 was showing good values. At the same time, while in there, I made the famous additional tie-back from J108-1 to J4-1 (the original one was still in place).

Now when I start the game, I'm till getting this S37 locked and I don't know what to check next!

Thanks in advance!
Pete.

#2 10 days ago

Well I hate to say this but you may have to start all over again
Before the pre driver you should have replaced the main transistor for that solenoid on the driver board.
1.replace the main transistor
2.replace pre drive transistor
3.replace coil(if it is fried/burnt)if not then replace the diodes on that coil
4.replace blown fuse
Look in the manual and make sure you are locating the correct main transistor on the driver board.A locked on coil is always usually a bad/shorted main transistor

#3 10 days ago

Make sure the tieback wire from the single drop hasn't fallen off. Symptoms are the diverter coils lock on.

I added a weebly solenoid saver fuse board to mine so that the solenoids controlled by the 8 driver board are separately protected.

https://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Blown_.2F_Failing_Q20_Transistor_on_the_Driver_Board_and_the_Tieback_Diode

and

https://www.pinwiki.com/wiki/index.php?title=Star_Trek:_The_Next_Generation#Diode_.22Tie_Back.22_missing_causes_8-Driver_Board_transistor_to_fail

#4 10 days ago
Quoted from pinmike:

Well I hate to say this but you may have to start all over again
Before the pre driver you should have replaced the main transistor for that solenoid on the driver board.
1.replace the main transistor
2.replace pre drive transistor
3.replace coil(if it is fried/burnt)if not then replace the diodes on that coil
4.replace blown fuse
Look in the manual and make sure you are locating the correct main transistor on the driver board.A locked on coil is always usually a bad/shorted main transistor

Thanks for your answer Pinmike. Before I start to replace it all again I'd like to confirm few things (sorry, I'm not an expert so I may have stupid questions):
1. Is the main transistor Q16 (TIP102)?
2. Is the pre driver Q8 (2N5401)?
3. Coil is brand new, and does not seems to be damaged yet. (Locks itself when game started and comes back in position when switched off, good values on the tester). Diode was there from factory and is then brand new too, it should be replaced as well?

Should the Diode, Q16 and Q8 be replaced even if tester is showing good values?

Thanks again!

#5 10 days ago
Quoted from slochar:

Make sure the tieback wire from the single drop hasn't fallen off. Symptoms are the diverter coils lock on.
I added a weebly solenoid saver fuse board to mine so that the solenoids controlled by the 8 driver board are separately protected.
https://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Blown_.2F_Failing_Q20_Transistor_on_the_Driver_Board_and_the_Tieback_Diode
and
https://www.pinwiki.com/wiki/index.php?title=Star_Trek:_The_Next_Generation#Diode_.22Tie_Back.22_missing_causes_8-Driver_Board_transistor_to_fail

Thanks Sochar as well, I checked the factory tie-back and it's working. I've also added as you suggested a second one from J108-1 to J4-1.

Tested to start the game with or without it and it does the same thing.

#6 10 days ago
Quoted from lemanp:

Before I start to replace it all again I'd like to confirm few things (sorry, I'm not an expert so I may have stupid questions):

Oh no it's never a stupid question,It's always best to ask before trying something your not sure of

#7 10 days ago
Quoted from lemanp:

1. Is the main transistor Q16 (TIP102)?
2. Is the pre driver Q8 (2N5401)?

Yes that does sound correct,Tell you what let's try a quick test of that main transistor Q16 first Ok.This test is 95% accurate let's give a try
1.Power off the game!
2.set your meter to continuity setting
3.Place black probe onto ground(Gray metal strap in backbox)
4.Touch the tab of that transistor Q16 with the red probe
5.If the meter beeps it means that transistor is bad/shorted

#8 10 days ago

I usually add diodes to the divertor and drop coils for redundancy.

#9 10 days ago

Just some info for future reference

Whenever a coil is locked on don't just replace the coil with a new one because the coil does not go bad unless it fried/burnt.
If there are diodes on that new coil the one your going to install it will in many cases short out those diodes on that new coil.
Always test main transistor first

#10 10 days ago
Quoted from pinmike:

Yes that does sound correct,Tell you what let's try a quick test of that main transistor Q16 first Ok.This test is 95% accurate let's give a try
1.Power off the game!
2.set your meter to continuity setting
3.Place black probe onto ground(Gray metal strap in backbox)
4.Touch the tab of that transistor Q16 with the red probe
5.If the meter beeps it means that transistor is bad/shorted

Game on (front door opened to avoid the coil S37 to fire)
Meter on continuity with sound
Put the black pin from the meter on the gray metal strap on top of the backbox
Put the red pin on the Q16, no sound (also tested all the other TIP102 from the same PCB) - I guess by "Tab" you mean the metal part on top?
Tested with red pin on metal backplate, it beeps correctly
Tested also on J3-7 and J4-7 and it beeped as well (guess it's expected)

#11 10 days ago
Quoted from lemanp:

Game on (front door opened to avoid the coil S37 to fire)
Meter on continuity with sound
Put the black pin from the meter on the gray metal strap on top of the backbox
Put the red pin on the Q16, no sound (also tested all the other TIP102 from the same PCB) - I guess by "Tab" you mean the metal part on top?
Tested with red pin on metal backplate, it beeps correctly
Tested also on J3-7 and J4-7 and it beeped as well (guess it's expected)

NO!! Game Off!!!

#12 10 days ago
Quoted from pinballplusMN:

I usually add diodes to the divertor and drop coils for redundancy.

Thanks for helping pinballplusMN!

I checked and all coil have a diode in place. My new S37 already had a diode from factory.

#13 10 days ago
Quoted from pinmike:

NO!! Game Off!!!

Ooops red too quickly ...

Just did it game off, same story

#14 10 days ago

Attached a PCB picture where you can see the new Q16 as well ^^

IMG_20200113_144420 (resized).jpg
#15 10 days ago

Ok Q16 is the one that is silver..Tab means the tip of that transistor,Does meter beep when you touch it with red probe.

#16 9 days ago
Quoted from pinmike:

Ok Q16 is the one that is silver..Tab means the tip of that transistor,Does meter beep when you touch it with red probe.

Sorry, wasn't able to post earlier due to restrictions on my newly create forum account.

I've done as you've suggested and no, no beep on the Q16's tip nor any of the other transistor on that PCB.

#17 9 days ago

Up/help

#18 8 days ago

Just to make sure is that the correct transistor for that coil that is locking on?Did you check the manual for location on driver board?
The reason I’m asking this is because for 2 coils to lock on and main transistor and pre driver transistor are testing to be good is highly unlikely

#19 8 days ago
Quoted from pinmike:

Just to make sure is that the correct transistor for that coil that is locking on?Did you check the manual for location on driver board?
The reason I’m asking this is because for 2 coils to lock on and main transistor and pre driver transistor are testing to be good is highly unlikely

I can't explain why, had everything rechecked again and didn't found anything ... try to start the game again and it's now working fine! There must be a short somewhere but I did not find it. However it's working now so thanks for helping mate!

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