(Topic ID: 192403)

Replacing subway diverter on Star Trek TNG

By locutus

6 years ago



Topic Stats

  • 7 posts
  • 4 Pinsiders participating
  • Latest reply 6 years ago by locutus
  • Topic is favorited by 1 Pinsider

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#1 6 years ago

Hi Pinsiders!

This is my first post but I have been using this site since I acquired my first pinball, a Star Trek TNG. The site has been a tremendous resource and helped me get her running and gave me a few solid months of solid pinball action. Then randomly one game the ball just kept loading over and over. Poking around on here led me to look at the diverters on the subway and sure enough one of the solenoids was totally fried. I attached an image where you can see how the inside is blocked by the melted part.

So I ordered a new one of those and replaced it and also found a burned out fuse but still that doesn't work. The other solenoid for the top diverter works fine. This led me to look at the board which you can see in the photo has had better days. Looks like the former owner already worked on this and the solder doesn't look so good to me. I found a new board online for about $40 so I figure I will just replace it rather than keep hacking on that one.

Anyways, my question for you all is if you look a the image where the solenoid is attached to the subway, you will see the two purple wires attached to the right side. I was noticing in all the photos I could find on here that those wires are attached the opposite way that they were on mine. Whats up with that? How was it this was working fine for a while? One of my theories on why it went south was that it was really loose and had a lot of play so I am guessing that after a while it just wore out.. I dont understand why it looks so melted. Well thanks for any tips you could give me. Like I said my next step is to replace that circuit board but I dont want this to just happen again if there is something else I should be aware of.

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#2 6 years ago

The side of the coil the double wire is soldered to is meaningless on STTNG. If you want them all on the same side, you can move them.

Make sure your new coil DOES NOT have a diode installed. If it does, either remove it (there is a diode on the driver board to serve that function) or make sure the double wire is soldered on the coil lug with the banded side of the coil diode.

The repair work on your aux board looks good to me. Sometimes the traces on the boards of this era are very fragile and need to be repaired when a component goes bad. The only thing that looks questionable is the Diode above the transistor on the top of the board appears burned. It might be a good idea to replace that.

Back to the problem, the diverter coil that failed looks like it failed ON which is usually caused by the driver transistor failing shorted. I would be suspect of that aux board transistor for that diverter coil. It is probably blown shorted. If the diode above it failed, it will cause the transistor to fail prematurely.

#3 6 years ago

You should take a look at this article in PinWiki.

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

Also:
The TIP on the 8 driver board is most likely blown. Again ??
Also think about replacing the pre-driver. It might look good without load. It's not expensive and only takes a few minutes to solder when the board is out anyway.

Final thing...
On the picture - it looks like the Solenoid is an AE-23-800 ??? Please chek. I think (but not sure) it should be a AE-23-1000.

#4 6 years ago

Plenty of good advice on here already. You will not want to turn this machine on again (or at least not the HV) until you have:

1) repair the tieback wire, its a small violet-green wire connected to the drop target, I'm going to say there is a 99.9% chance that its broken.

2) replace coil sleeves and both coils with the appropriate AE 25-1000 coils http://www.pinballlife.com/index.php?p=product&id=158

3) Repair or replace the 8 driver board as appropriate

Failure to perform ALL of these things before powering on the game will result in blowing the drive transistors, and frying the coils and aux driver board again.

Good luck

#5 6 years ago

Thank you so much for all your help! Wow about the Solenoids! I was just replacing what was there but you are right, that was the totally wrong one! Do you think that could have been a cause for the failure? I checked the tieback wire and that looks good to me. I have ordered new solenoids and I decided to just replace the entire circuit board as it was pretty cheap. I can use this old one for soldering practice. Unfortunately I did not take very good before pictures before I dismantled everything. Here are some photos of it, it seems like someone got pretty creative with this wiring. I am a little confused, is there supposed to be one of these attached to J105. Thanks for your help with this, obviously I dont really know what I am doing

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#6 6 years ago

Yes – those solenoids (and diodes) …

Yes – different solenoids will have different resistance (Ohm). So replacing a solenoid with one that does not meet the specs can possible result in drawing more current through the transistor – thus burning it.

So – my advice would be to repair the driver and pre-driver transistors. And check the tie-back by measuring continuity. Don’t go for a visual inspection alone!! Either measure it and make sure it’s good, or go for one of the instructions I linked to at PinWiki. If you don’t make sure the tie-back is good, you’ll risk burning transistors and the diverter solenoid again!!

Regarding connections there is good help to be found in the Operations Manual. You can find a PDF version on ipdb.org.
STTNG: http://www.ipdb.org/machine.cgi?id=2357
Or use this direct link: http://mirror2.ipdb.org/files/2357/Williams_1993_Star_Trek_The_Next_Generation_Operations_Manual_with_OCR.pdf

In the Operations Manual on page 3-24 you’ll find the illustration shown below of the connections for the 8 driver board.

Reading it you can see that
J1 is for the ribbon cable (which you did not attach on the pictures. Remember red wire goes on pin 1)

J2 pin 1 is black
J2 pin 2 is key (pin “missing” on the male connector)
J2 pin 3 is gray
J2 pin 4 is black
J2 pin 5 is black
J2 pin 6 is gray and green

You can read the rest yourself
But note that all connectors are in use on the 8 driver board.

In the manual you’ll find the same information about the power driver board. Only difference is that this board has so many connectors that the information is spread over 3 pages. You’ll find the information you need on page 3-33 to page 3-35. Also note that not all connectors on the power driver board is in use. N/C means Not Connected. So when you ask about J105 you can see that it’s not in use since all pins says N/C.

Good luck!
Henrik

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#7 6 years ago

Thank you again. I have it working again and it is running better than ever!! I think those wrong solenoids must have been draining power from other things as my bumpers seem a lot stronger now. I really appreciate all of your help!

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