Is your machine set to 5-ball play? Make sure it's set that way, and then look at this drawing - it's the add bonus part of the schematic simplified a bit. I left out some F relay and Green Drop target switches that complicate things. But for looking just at the D (and E) relay, this should work.
Vulcan add bonus simplified (resized).jpg
I don't know what you know and what you don't know, so I'll start at the beginning - plus, you never know who's gonna be reading this in the future, so don't be offended if I man-splain.
That Motor Sequence chart on the left is important because it tells you the timing of how switches open and close relative to each other on the score motor. The thick black lines indicate a change in switch state - not closed or open specifically, just a change in state from how they're drawn on the schematic. And Gottlieb schematics are usually drawn with the score motor in the home position (at zero degrees of rotation on the chart), single-player game started, machine unplugged.
So, for example, the Motor 1A switch is drawn as normally-open. That means that as the score motor rotates, and you follow the line on the chart for the Motor 1A switch, every time you see a black line, the 1A switch is changing state - that is, in this case, closing.
The other score motor switches - 2C, 4B, 1B and 4C - are all drawn as normally-closed. That means that they start as closed, and as the score motor rotates, and you trace their line from left to right, every time you hit a black line, the switch will open. It's the reverse of the Motor 1A switch on the chart.
So we're trying to figure out how many times a 25V pulse can get through the circuit to the "Add Bonus Unit" coil. Every pulse that makes it through that gauntlet of switches will fire that coil, and increase your "Add Bonus Unit" stepper one time for 1 bonus position.
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The whole process starts when you hit a drop target and the D relay energizes. This closes the D switch on the drawing. D shouldn't relax until the end of a score motor cycle when a Motor 2B switch opens.
There is a switch on D that starts the score motor turning.
Once the score motor starts to turn, the Motor 1A switch is going to open and close 5 times. Think of it as providing 5 voltage pulses...so how many of those voltage pulses will get through to fire the "Add Bonus Unit" coil?
The 1st pulse from Motor 1A gets all the way through to the "Add Bonus Unit" coil because none of the 4 motor switch in series have opened yet and the D switch is closed...so 1 pulse. Your bonus is increased by 1K.
The 2nd pulse from Motor 1A occurs at the same time as switch Motor 2C (look at the chart) is opening. That blocks the 2nd pulse....doesn't get through.
The 3rd pulse from Motor 1A occurs at the same time as switch Motor 4B is opening. That blocks the 3rd pulse.
The 4th pulse from Motor 1A occurs at the same time as switch Motor 1B is opening. That blocks the 4th pulse.
And finally, the 5th pulse from Motor 1A occurs at the same time as switch Motor 4C is opening. That blocks the 5th pulse.
So the effect is that only 1 pulse from Motor 1A gets through each time you hit a drop and the D relay fires. You should only get one bonus increase.
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Now look at how relay E changes things. When rollover switches are hit, and any of relays 1B thru 5B are tripped, Relay E is fired when you hit a drop target tied to that relay instead of Relay D. So picture the drawing above with the D switch open and the E switch closed. E also starts the score motor turning, but this time the 1st pulse from 1A gets through to the Add Bonus Unit coil, AND the 2nd pulse gets through because the closed E switch gives it a path around the open Motor 2C switch. The remaining 3 pulses from 1A are still blocked, so the result is 2 pulses to the Add Bonus Unit coil - an increase of 2 bonus. That's why the E relay is labeled "500 POINT AND ADD 2 OR 3 BONUS RELAY".
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So, anyway, that's the long version of how the D relay is supposed to add bonus - 1 at a time. If yours is adding more than 1 bonus at a time, then more of those Motor 1A pulses are getting through than should be getting there.
Putting the machine on 3-ball changes some things. So make sure your machine is on 5-ball, while we try to troubleshoot it.
I might start by blocking those 4 motor switches in series (put a strip of paper or something between the contacts), then firing the D relay and seeing if any bonus is added. There shouldn't be.
Also, as you've probably noticed, you can't always assume that a switch is conducting electrically just because it's closing visually. I had a switch that I had cleaned with a Dremel tool brush and alcohol - both contacts were so shiny and clean that I could see my handsome face reflected back in them. But I had cleared the playfield and a drop of clear fell onto one of the contacts. You couldn't see it, and the contacts were definitely touching, but one was coated with clear...so, no electrical contact. That's where a jumper was useful in troubleshooting. Or sometimes contacts are loose in the leaf and aren't making good electrical contact.
Sorry about the long post!
Boulder, CO
So it could still be some of those switches from post 14 and maybe they still aren't working.
