Not familiar with Fireball but I assume it's the same as the earlier 4MBC.

And yeah, usually a game has a switch on the hole. That switch triggers a relay, that relay turns the score motor. The last step of the score motor, through another switch on the relay, fires the kickout. In the case of a lock like this for multiball, the hole switch instead makes another ball eject from the trough, and leaves the ball in the hole, and later a target/bumper triggers the hole kickout.

Bally had a really cool, simple system to control the trough where it basically watched how many balls are in the trough, and how many balls are locked on the playfield, and if it saw that no balls were left in play (and the outhole wasn't triggered), then it'd kick out another ball from the trough, so there's no actual direct connection between the ball entering the kickout hole and the trough releasing, it's just a general check of the whole playfield state

It works exactly like later digital multiballs like Firepower, and it's quite genius.

THere are (I think) three switches in the trough. Unlike modern games, where the switches are below the playfield pointed up, these are installed in the walls of the trough, facing the player. Just like a modern game, Fireball keeps track of how many balls are in the trough, and how many balls are in the lock holes on the left or right, and deals out balls accordingly.

4MBC and then the Fireball.

4MBC Multiball control (resized).JPGFireball multiball control (resized).JPG

Hats off to the designer! When I had a Fireball, never problems with the multiball logic.

I am having issues with a 4MBC. Haven't had time to dig back into it but has been a challenge to find the issue. Had pulled the bottom board and went through everything but some odd crap happens. It get's pretty whacky when this happens. I will try to post videos and the root cause when I find out the issue. A Google search didn't show anyone with a similar issue.

If during testing, you remove a ball from the tar pit without activating the tar pit exit, it gets confused.

(side note: do mechanical things get confused? )

Confused is as good a word as any. By manually moving the ball you've put the game in a state (a certain combination of stepper, interlock relay, Score Motor, etc. positions) that the designer optimized out of the design because they can't be reached during normal play with the glass on. Covering those 'illegal' states would have added extra hardware and cost.

Gottlieb had a similar behavior for a while if the game was unplugged while the Score Motor was running. The game wouldn't start if the Score Motor wasn't in its index position. (see https://pinside.com/pinball/forum/topic/replay-button-doesn-t-start-a-game-by-design)

/Mark

That's what I meant by a Google search. That's the only multi-ball issue that is stated, the tar pit and if the Lock Relay is active or not. When the ball enters the tar pit the Lock relay engages. This closes the Tar Pit gate and prevents an additonal ball from being captured. The lock relay is then released when the ball exits the tar pit. If the Lock relay is engaged and there is no ball in the Tar Pit, at the start of a game you will have two balls ejected instead of just one.

That's an easy one. Wish that were my case.

The bevaior on my 4MBC is odd to say the very least.

One out of 3-4 games it will play correctly.

On occasion it will spit out two balls at the start of a new game and the Lock relay is not energized and no ball in the Tar Pit.

On occasion after releasing the captured balls from the Tar Pit and Volcano, three balls in play, when a ball drains it may then immediately get ejected into the shooter lane again.

And on occasion shooting a new ball will only momentarily light the pops as the ball makes the roll over contacts on the skill shot, they do not latch. And it really loses it's brains on the ball count when this occurs. It has to be powered off to clear it.

I pulled the lower board, cleaned all the contacts, steppers cleaned up and fucntion properly, replaced the burnt coils and went through the score motor. Also went through the playfield including Tar Pit and Volcano.

What sucks about this pin is it is impossible to reach some relays in the bottom board without removing the playfied. And many of the relays in question reside in the very rear of the board.

I'll get videos of it at some point. I missed something but not sure what.

While on the subject of these multi-ball Bally's with 2" flippers, I can't praise them enough. I am not a 2" flipper guy at all but the 2" Zippers were genius when paired with mulit-ball. If you've never played on I suggest you give one a whirl. Clay will be having the Ann Arbor Pinabll show soon and if you have never been you should try to make it, an incredible collection to include the multi-ball Bally's.

Would love to have a Fireball sitting next to this 4MBC. Great pinball machines!

The simplest explanation might be that the #3 Trough switch is gapped too close and fires the Ball Release relay a 2nd time as the 1st ball is being kicked to the shooter lane.

/Mark

I will check it again Mark, thank you.

You’re correct so far keep going.

The best part is when my son has both Odin and Wotan locked and then I steal them on my next ball! But, he does have the high score on Fireball.

Once again @MarkG, you're understanding of the EM pinball circuit is astounding! The time you take to help others is appreciated! Some really sharp individuals on this site.

From the explanation I gave, you nailed it. Problem fixed. Thanks again MarkG!