mystic line extra ball design flaw
discovered by ernie hite

Games affected: possibly all mystic line machines. certainly all the later ones.

update 02/12/2002 : After writing all this up, ernie then pointed out it makes no difference at all in terms of actually getting an extra ball, but it does appear to the player to make a difference. See the why it doesn't matter page.

Ernie wrote in about the extra balls on his super-7 machine. He noticed that the extra balls never single stepped to the "extra" panels. The machine would sometimes award an extra ball by "running" all the way to the "ball" panel, and it correctly lit at least the "1st", "2nd" or "3rd" panels when the machine was cycled (e.g. on the first extra ball spin cycle, the "1st" is guaranteed to light. When you have "1st-extra-ball" all lit, the next cycle will guarantee at least "2nd" will light).

Note: The following pages refer to switch 6A/6B. One some games, it's switch 6A (safari), and others it's switch 6B (super-7, bonus-7, hawaii, double-up). You should check your manual to see which switch on control unit cam 6 is the "extra ball" one. Got any doubts, zap me a comment and I'll look it up. Thanks Hugh for catching this!

Circuit Theory

If you hate tedious circuit descriptions, skip this part and move on to the timing cams page to see if your game has this problem.
super 7
extra ball step up circuit

There's three ways the extra ball unit can step-up. The green circuit is the guaranteed step which advances the unit to the 1st/2nd/3rd panels when appropriate.

The other two ways require 50V to come from the mixers and reflex disc. The purple circuit shows the 50V coming from the mixers, and if it gets as far as wire #18-2, then CU cam switch 8A should pulse the extra ball coil to step the unit up once. The purple circuit also feeds the last way which runs through the spotting disc and pops out along the blue wires.

The blue wires are the multi-step circuits. Get the 50V through the spotting disc and mixer #4 and the extra ball unit will advance far enough to give you the next ball. Notice the affect of the adjustment plug - it adds more paths in the circuit, so to make the game the most liberal, connect the plug so all the wires hook up.

Anyway, the important thing to notice is why CU cam 6 switch is in the circuit way up on the top right. If this switch did not open while the spotting wipers were turning, then you could intermittently get a pulse sneaking through the multiple step circuit whenever the spotting disc was passing the 50V and the mixer & spotting 16 pulse cam 5B switch closed.

For the single step circuit, we need 8A to pulse closed while 6A/6B is closed.

timing cams | suggested fix | why it doesn't matter