(Topic ID: 306904)

Williams Stardust

By PatrickLewis_net

1 year ago

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  • 16 posts
  • 6 Pinsiders participating
  • Latest reply 1 year ago by HowardR
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#1 1 year ago

I have a Stardust game that is blowing the main fuse (110V). Previous owner said there was a cloud of smoke and the whole game went dead. The transformer is labeled as 15B-6781-1 at 50Hz. I removed all of the leads from the top of the transformer, so just the bottom leads are attached. It still blows the main fuse.
Does anyone rebuild these? Or, can I replace it with a more modern transformer? Does anyone know the Amps that it puts out?

Added 13 months ago:

I renamed this without the Transformer, since that part is now resolved.

#2 1 year ago

It does sound like your transformer has fried. This is a very rare problem, but it can happen.

In the USA, the primary side of the transformer is designed for 120 VAC at 60 Hz. I'm assuming that you are in Europe because you are using a 50 Hz transformer.

In any event, you can definitely replace it. These were large and rugged transformers that were made by the Electrical Windings Co in Chicago, who specialized in producing transformers for the local pinball factories. If possible, you should try to find a used transformer of the same type, perhaps from a salvage parts game that someone is selling.

These transformers rarely go bad, so it is possible to get one from a game that was scrapped for other reasons. Because of the very high output current that these transformers need to supply, I think finding a used factory original is the best way to go.

While it is possible in theory to replace your game transformer with a new one, it can be challenging to find a new transformer with the necessary output current. As far as I can tell, the original Williams EM transformer could supply at least 20 amps at 6 volts, and 15 amps at 28 volts. So, if you are going install a new transformer, it would need to provide this kind of output power.

- TimMe

#3 1 year ago

Just to add a bit more information on this - the secondary of these transformers provided two output voltages: 6 VAC at 20 amps or more (for the lamps), and 24 to 28 VAC at 15 amps or more (for the coils).

Also, I should also mention that any salvage Gottlieb EM transformer from the 1970s would also work as a replacement. While some may cringe at the idea of a Gottlieb transformer in a Williams game, at least it would get your game working.

Note that you could not use a salvage Bally EM transformer as a replacement, however, because the coil output on these was at 55 volts rather than the 28 volts used by Gottlieb and Williams.

- TimMe

#4 1 year ago

Thanks for the info. I updated my profile with my location. Brandon FL (tampa). Sounds like it is best to get a used one rather than get it refurbished. Off to ebay I go.

#5 1 year ago

The new transformer gave life to the machine, but I have a short happening on the 10 point relay in the back box. It's happening on the connector with the yellow and black/yellow(?) wire that is in the back row, second from right. See the picture.

I have tested on a 3-player game and it sparks on all players. It will eventually blow the 24v/15A fuse.

I need some guidance to help trouble shoot this. I have the schematic for the game.

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#6 1 year ago

Arcing doesn't imply a short, but if you're blowing a fuse something is going on. The switch is driving the Match Unit solenoid.
Stardust 10 pt relay (resized).jpg
Does the Match Unit advance every time you score 10 points? Is the solenoid an A-22-550 coil? How does it look?


#7 1 year ago

One thing to remember on these Williams woodrails is that the high tap is selected by inserting the fuse in the high tap slot. You can not have fuses in both slots, so either the normal, or high tap fuse holder must remain empty.

#8 1 year ago

The match unit does not advance. It is an A-23 600 coil.

I also removed the top fuse. Still don't like the sparking.

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#9 1 year ago

Williams went from 50V to 24V.
That looks like a more modern coil. It could be incorrect for that game.

#10 1 year ago

Yeah, schematics say it should be the A 22 550. Looks original, though.

#11 1 year ago
Quoted from PatrickLewis_net:

The match unit does not advance.

That's not much to go on. Does it try to advance when the 10 point relay fires? Does it advance if you push the plunger in manually?

If you desolder one of the wires to the coil does the problem go away? If not the coil could be fine but you might have a short elsewhere.

An A-23-600 coil has a slightly higher resistance than the A-22-550 on the schematic. But if the coil is damaged its resistance could be much lower and it could blow the fuse. What's the resistance of the coil? It should be a little over 3 ohms according to https://www.flippers.com/coil-resistance.html.

#12 1 year ago

I unsoldered one of the wires and the sparking went away and the game plays great otherwise. I can manually advance the unit, but the coil does not seem to even try.

I did notice on the player unit that there is a section of the gear with no teeth. Is that normal or does this need to be replaced?

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#13 1 year ago

The missing teeth keep the Player Unit from stepping to player 5.

#14 1 year ago

Check the resistance of that coil. There is a chart online that has the approximate DC resistance of most coils. If it’s close, then it’s something else. If the resistance is low (like 1 ohm or less), then that could be your short. Depending on where you disconnected the wire, it could still be something that’s not the coil, such as another tie point or broken insulation allowing the wire to touch another connection. The problem with a short circuit is that it’s not shown on any schematic. Also remember that a schematic is a logical representation of the connections, not a physical layout. Just because it shows a connection between a switch and a coil doesn’t mean it doesn’t go through a Jones plug or a tie point, etc. Youre making progress with your isolation, so that’s good.

Good luck,


3 weeks later
#15 1 year ago

Does this unit act like a distributor on a car? Do the wheels with the many teeth trigger the power to the other wheels when they hit the dimples? Or should there always be power to the individual stacks?

I have cleaned the contacts on all of the switches, but now the score reset does not trigger when the game start button is pushed (in free mode). Also the flippers and scoring do not respond.

I feel that I may have broken a connection somewhere when cleaning the contacts.

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#16 1 year ago
Quoted from PatrickLewis_net:

I have cleaned the contacts on all of the switches, but now

Sorry but that was a mistake. This forum is full of posts from people who tried shotgun cleaning & adjustments, and caused more problems than they were originally trying to solve.
What to do instead: Slowly and carefully diagnose one problem at a time and then fix only that.

Quoted from PatrickLewis_net:

now the score reset does not trigger when the game start button is pushed (in free mode). Also the flippers and scoring do not respond.

If pressing the Replay button doesn't activate the Replay relay, Inspect and diagnose this circuit with Alligator clip jumper wires

Example of a pinsider actually doing this https://pinside.com/pinball/forum/topic/red-baron-tech-question#post-5858156

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