(and honestly not really worth it. Nip-it's notoriety stems from it being in the retro sitcom Happy Days. Otherwise, the gameplay is just OK)
...and after playing a few games, I noticed that Nip-it had a problem:
|Nip-It when it first came home|
After the ball in play would drain, the ball count unit wouldn't always step up. If it was the 5th ball, the game would not go to game over. This happened once in a while.
I had a good look at the schematics and made sure every element involved in the circuit was clean and properly gapped.
|Bally Nip it schematic detail for ball count unit.|
The circuit does go through the coin unit disc. But in first position (i.e. 1 player game) the juice is patched to the ball count unit. All the malarchy with the player up disc interplay with the coin unit disc is to step up the player up unit, instead of the ball count unit, in a multiplayer game.
The stuff regarding the ball count disc and the balls per play adjustment has to to with the game over relay. Not relevant for the problem at hand.
Basically, in normal play. Once the game is conditioned to release the ball (ball release re. switch closed) the ball index re. switch is closed (because points were scored), 2nd Ball re. switch is closed because there are no free moving balls still in play. SCM 3b switch is momentarily closed (because the cams are rotating) and the juice energizes the ball count unit step up solenoid by way of the coin unit disc.
The core of the matter was the 2nd ball relay sometimes not energizing when it was supposed to. After the outhole kicker kicks the ball to the ball trough, the 2nd ball relay should energise if both balls are out of play.
"Out of play", that is:
Both balls are in the ball trough
One ball is in the trough and the other is in the captive hole (i.e. no free moving ball(s) in play).
Only then is the ball count unit allowed to step up through the 2nd ball relay et al.
The problem is that for the 2nd ball relay to energize the Outhole relay has to be energized.
|Bally nip-it schematic detail for outhole relay and outhole relay|
The Outhole relay is energized by the outhole switch through SCM 1c N.C. switch. The relay is then held in through itself and SCM 10c normally closed switch.
What happens is that once kicked, the ball traveling in the trough has to be in place on it's trough switch before the outhole switch circuit is broken. Otherwise the 2nd ball relay won't energize and the ball count unit won't step up.
|Nip-It outhole kicker schematic detail|
A Bally score motor spins at 26 rpm and s spin cycle is 180 degrees (half a turn). So one SCM spin cycle lasts 1.15 seconds. Furthermore, a 180 degree spin cycle is divided into 8 periods (0 to 7). one period is 0.14 seconds. The ball is kicked up the trough at period 2. The outhole relay hold in circuit is broken at period 7. That allows a whole 0.72 second (maybe a bit less, my math is a bit sloppy) for the ball to make it from the outhole to it's ball trough switch. That's not much time. If the ball does not make it on time, the outhole re. de-energizes and the 2nd ball wont energize, a ball is released to the shooter lane and the ball count unit won't step up.
|Nip it Score Motor sequence of operation|
If the outhole kicker punts the ball, which happens every once in a while in these old games, the ball takes too much time to make it to the trough switch, the outhole relay de-energizes, the ball is not in place and the 2nd ball relay won't energize.
Basically, for the game to work properly 100% of the time, I needed more time allowed for the ball to make it to its trough rest position. I needed the SPDT switch on the outhole relay the remain actuated a second or two more to allow enough time for the ball to find its rest position in the ball trough.
This could not be achieved within the machine as it was. I needed to take out the SPDT switch from the outhole relay and put in on a delay relay that I would shoehorn into the game. I used a simple delay circuit found in a bingo machine. So basically, Bally already had this circuit in it's Bag-O-tricks at the time, they just didn't use it in Nip-It.
|Delay relay schematic diagram, Inspired by the circuit found in Bally Bali bingo, but adapted by pindude152|
|Modified Nip-It Schematic detail. SPDT switch now on delay relay|
So what now happens is that the outhole relay would energize the delay relay. The delay relay would remain energized as long as the outhole re. would be energized, but the delay relay would allow the SPDT switch to remain actuated for a couple of seconds after the outhole relay would de-energize. Enough time for the ball to make it to the trough switch. And bingo! the game now plays like it should.
|Delay Relay shoehorned into Nip-It. The 2 capacitor setup looks a bit "Ghetto" but I didn't have a 2000uf 50V capacitor, so I put 2 x 1000uf caps in parallel. It works but it aint pretty.|
Up until now, my mantra was "the problem is always inside the cabinet". But for nip-it it turns out the solution was outside the game. When the game was brand new, it probably worked like clockwork but after 40 years, the game still works OK, but not perfectly under every possible circumstance, so to palliate the subsidence of the game into kipple I had to slightly modify the game, especially if I intend to operate this game.