(Topic ID: 265738)

Strange World scoring/relays question


By paulace

52 days ago



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  • 9 posts
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  • Latest reply 51 days ago by paulace
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0Sp-Mi-Work-20c-Save (resized).jpg
Strange World Q & E relays circled (resized).jpg

#1 52 days ago

I have been thinking about a friend's Strange World (1978) and have a question regarding how it scores 500 or 5000 pts, depending on which targets/rollovers have been hit. There are 12 targets/rollovers on the pf - numbers 1, 2, 3 and 4 in white, yellow and green. Hitting any of them gives you 500 pts UNTIL you've hit all three of the same number in each color. So, for example, the first time you hit a yellow 1 - you get 500 points. If during the game, you hit all three of the "1"s (yellow, white and green), then they light up and the next time you hit a "1" of any color, you get 5,000 pts. I hope I described that clearly.

The involved circuitry is attached. I've circled the switches involved in the 500 pt circuit in red, and "squared" the 5000 pts switches in green. The Motor 1A switch is circled in blue and gives the 5 pulses to the appropriate relay (L or M). Switches 1Y, 1W, and 1G are on latched relays, so once the relay fires, those switches change state (close) and stay that way for the rest of the game.

So if I understand this correctly (and please jump in if I'm mis-understanding), let's just look at the #1 yellow target switch for now. When the ball hits the #1 yellow target, the two switches circled in red on the right close. There is now a closed circuit to the Q relay, circled in red on the left through the n/c E switch in series with it. Relay 1Y also is energized long enough to close switch 1Y in the green box, which stays closed. Q being energized then closes the Q switch down below circled in red that allows the 5 pulses from Motor 1A to get through to the 100 pt relay (M) and thus you get 500 points. It stops when Motor 2B opens toward the end of the cycle and de-energizes Q.

But once you've hit all three of the 1's (yellow, white and green), those three switches in the green square (1Y, 1W and 1G) all close. This is where I get confused. Now that those 3 switches on latched relays are closed, the next hit of any of the #1's will allow current through those switches and the n/c Q switch in series with them to energize the 5000 pt relay (E). The lowest E switch then closes, allowing the 5 pulses from Motor 1A to go to the 1000 pt relay (L) instead of to M, where they were going before.

I'm confused about the timing, though - Let's say all 3 of the latched switches in the green box are closed - the ball hits a #1 target and 2 switches close - both circled in red on the right side of the drawing. One should energize the E relays as I just described, but the upper one should energize the Q relay. Except that the n/c E switch in series with the Q relay would then open. My question is about the timing of what happens when the ball hits the target: It looks like the n/c Q switch in series with the E relay could open just as well and keep the E relay from energizing. This works, so obviously the E relay is being energized first, and locking out the Q relay, but why? Does that 10 ohm resistor in series with the Q relay have something to do with the timing of it? Do resistors slow current down? Are the switches physically placed so that the target switch that energizes E switches first? That would seem like a pretty unreliable way to do it, so I'm assuming that's not true.

Any sharp minds out there know? I'm very suggestible....

Strange World Q & E relays circled (resized).jpg
#2 51 days ago

The 10 ohm resistor is there to drop the voltage to the Q relay after the Target relay that fired it in the first place drops out. In other words, the Target relay is only active as long as the ball is closing the the target switch. The Q relay fires at the same time since it's in series, but needs to stay active through the end of the Score Motor cycle so the 500 points can be added. The resistor and the lock in switch on the Q relay are what keep the Q relay active until the Score Motor 2B switch opens.

All of the relay coils in this part of the circuit are designed to operate at less than the full 25 volts since they're wired in series. Without the resistor in place the Q relay would see less than 25 volts when it fires in series with one of the Target relays, but would see the full 25 volts as soon as lock in switch closed. The resistor drops the lock in voltage down to an appropriate level.

The 500/5000 point scoring dilemma looks like a race condition. If things happened instantly you could imagine an order of events where the wrong score would be added. Your theory that the targets are wired so that one switch closes before another is interesting. You could test that theory by shorting one switch or the other behind a target to see if you could get the wrong score. I bet you can.

What might make this reliable is the fact that things don't happen instantly but take a certain amount of time. So for example if the E relay can fire in less time than it takes the Q relay to fire and to open its closed switches that would be enough to make it reliable. Putting the E relay switch on the targets in front of the Q relay switches would certainly help bias things in that way.

/Mark

#3 51 days ago

Thanks @MarG - your input is always educational. I was thinking that just depending on the placement of the 2 switches behind a target, one for Q and one for E, would be unreliable because the difference in time of the 2 switches closing would be so small as to be negligible - but I guess not. When I've adjusted multiple switches behind a target, I've often tried to set them to close as close to the same time as possible, mostly so that they both close even on a very light touch. It's not possible, of course - the one closest to the target has to close first...but such a small amount of time! That's an interesting way to set up a circuit so that it depends on that tiny amount of time - but it obviously works. I've never heard the term "race conditions"...fits perfectly!
Thanks again - I always learn something in here!

#4 51 days ago

Hi paulace, MarkG +
paulace - have You seen (in reality, in the pin) these #1-YELLOW-TARGET- etc. Switches ? --- or do You do "studying schematics ?
(My) Space Mission, Grand Prix etc. with the "Unique Tilt Rollover" , https://www.ipdb.org/glossary.php#Tilt_Rollover comes into my mind. See the JPG - below the "my blue horizontal line" is what I would like to see (drawn) in the schematics - a three-bladed Make-and-Make-Switch. Above the "my blue horizontal line" is the drawing in the schematics - (faulty drawn) as two two-bladed Normally-Open Switches. In my Space Mission I do have Three-bladed Switch. Greetings Rolf

#5 51 days ago

Hi rolf - nice to hear from you. The guy who owns the Strange World will be bringing it to my house to work on soon, so I'll be able to actually look at the real switches, rather than just deduce what they must be from the schematic. Maybe that will clear things up.

#6 51 days ago

Hi paulace, MarkG +
and here the JPG, greetings Rolf

0Sp-Mi-Work-20c-Save (resized).jpg
#7 51 days ago

Hi rolf,

Yes, a single make/make switch would be more clear in that schematic. Not sure why they drew it the way they did.

#8 51 days ago

Race condition is an engineering term used to describe things that don't predictably complete the same way every time.

As a wild assumption pick a ball speed of 10' per second (about 3 playfields per second?) and a target switch gap of 1/32". In that case it would take the ball about 1/3 of a millisecond to travel far enough to close each switch. So one should close about 1/3 of a millisecond before the other. That can be a lot of time in electrical terms.

Experimenting with closing the switches out of order might prove your theory.

Be wary of Make/Make switches behind targets. I've encountered a couple (one here on Pinside I think) where the two outside leaves were incorrectly wired onto the first two leaves of the switch and the middle leaf was wired to the back. What happens on a light hit on the target is that only the first two leaves touch making a connection between two parts of the circuit that should never be connected together without the third leaf also being connected. Most of the time the target is hit hard enough to close all three leaves together so it makes no difference if they are wired out of order.

#9 51 days ago

Thanks Mark - I'll have my hands on an actual machine soon, I think. Then I can play with those E and Q switches and see if I can screw up the timing for educational purposes. It still surprises me that the engineers would just depend on that slight difference in the positions of the two switches for the timing, given that people like me can get in there and bend switch leafs, potentially clumsily - especially if I didn't understand that part of the schematic and how those switches need to operate. But, as you say, if 1/3 of a millisecond is a lot of time for an electrical circuit, then I guess it's not a big deal.

Thanks for your clear explanations, as always!

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