Seattle, WA
Here's a fun one for all you circuit gurus to puzzle out. Maybe you've already come across this one, but if not, I hope you find this interesting and informative.
I've been working on rebuilding a Bally Monte Carlo, and today I came across an unusual wrinkle in a portion of the lamp circuit. This may have been a (benign) design error, or it may have been intentional. Either way, I think it is interesting because this circuit does not behave how I expected. In fact, at first I thought something needed fixing, but after doing some troubleshooting and testing, it turned out that everything was working the way it should. I will post an update on how I figured this out in the next day or so.
Here is a description of the wrinkle, along with a schematic snippet. Note: The snippet has been simplified a bit for clarity, but all of the relevant circuitry is shown.
On this game, there are ten numbers you need to make. Five of the numbers are odd (1, 3, 5, 7, 9) and the other five are even (2, 4, 6, 8, 10). There are two kick-out holes, one for the five odd numbers, and the other for the five even numbers.
Each hole has five "spot" number inserts associated with it. During the game, each hole will have one of its five spot number inserts lit. If the ball goes into a kickout hole, whatever number is currently lit will be spotted (made) if the player has not previously made that number.
The lit spot number at each kick-out hole changes each time 10 points are made. On the schematic, you can see the wiper and rivets on the 00-90 unit disc that select the lit numbers.
Also on the schematic, you can see a reference to two trip relays called the ALL EVENS TRIP RELAY and ALL ODDS TRIP RELAY that actuate when all five numbers of each group are completed. There is a lamp control switch on each of these relays (highlighted in yellow on the schematic) that opens when each relay is tripped. The purpose of each of these switches seems to be to shut off the completed group of spot lamps for each kick-out hole.
The wrinkle is this: If you make all of the odd numbers, the ALL ODDS TRIP RELAY will trip and its lamp control switch will open, but the odd spot lamps will continue to stay lit if any even numbers are still lit. Similarly, if you make all the even numbers, the ALL EVENS TRIP RELAY will trip and its lamp control switch will open, but the even spot lamps will continue to stay lit if any odd numbers are still lit.
However, if you manage to make all ten numbers, and BOTH trip relays actuate, then all ten spot lamps for both kick-out holes will indeed go out.
The trip relays are definitely tripping, and the highlighted lamp control switches are indeed opening, but somehow all the spot lamps still get power if only one of the two lamp control switches is opened. Can you see why?
MonteCarloSpotLamps (resized).jpg
- TimMe
