Derby Triple 300 Showa era medal game

Presenting... another obscure horse racing themed game: Derby Triple 300

The Manufacturer and the year of production are unknown to me but I suspect it's from the early 70's.

One of my main collecting interests is electromechanical gambling machines. Earlier this year I became interested in Japanese gambling machines. I started perusing Yahoo Japan Auctions and stumbled upon an auction listing for a machine called New Mini Derby.

But more importantly, I became intrigued the the machines inner workings.

From the outside the machine looked alot like what was offered in Great Britain at the time but the inner workings are way more intricate.

The auction price for the New Mini Derby was a bit too much for me and I passed on it but soon after I found a listing for Derby Triple 300 so I purchased it off YJA.

I bought the game almost unseen. The machine was listed as Junk, but working. Locked with no key and there were no pictures to attest that the games was complete. I took a chance. The game was very similar to the New Mini Derby and I suspect it was produced by the same manufacturer. I presumed it was electromechanical because the play features were relatively simple.

It arrived in a very large box delivered by courier.

When I got the machine unpacked it was indeed locked, but with a bit of gentle prying, I got the game opened, and was happy to see it was complete except for the missing coin box. Its electromechanical alright... with 50 relays!

The box was obviously knocked about in transit and a few parts were out of place, Notably the payout tubes and a few printed circuit boards.

I also found a bit of treasure inside: One 1 Yen coin, one 5 Yen coin, one 100 Yen coin, 4 10 Yen coins and 20-ish Bally 10 Yen coin sized tokens. Score!

I gave the machine a good visual inspection. Put all the loose parts back in their place. Made sure there were no broken parts and that nothing (like a loose coin) might cause a short circuit.

Looked at the electrical nameplate. Despite the operation voltage indicated at 125V I had my doubts and ran the game off a variable transformer adjusted to 100V since the game is a Japanese domestic unit.

Inspected the Transformer, bridge rectifier and fuses that were hidden behind a panel. Notice the multiple taps off the secondary, probably to compensate for line voltage.

Once I ascertained the machine was electrically sound, I plugged it in and the game lit up.

I then flicked the coin switch and started a game. It didn't function very well but I could see the game had potential.

For repairs, I started by burnishing the pads on the printed circuit boards and I cleaned the wipers. There was a patina of oxidation on pretty much everything. 

There are 5 similar boards, each with a low RPM motor and a wiper. I don't have any technical details, but I suspect one is for the game sequence, one is for payout impulse, one is for flasher animation, one is for random odds and one is for random selection. None of the relays are labeled and I haven't taken the time yet to figure out what each one does.

The game is well built with quality connectors. All the Relays are Omron sealed relays mounted on socket bases. The lamps used are 30V ba9s base and replacements can be easily found.

The machine has a basic attract mode where two lamps behind the panel "Derby Triple 300" flash alternately by way of a simple flasher circuit when the game stands unused. The flasher is interrupted when the machines is coined up and resumes after a spin cycle.

The machine uses an adjustable coin rejector and I adjusted it to .984 standard pachislo tokens.

The coin slot has a coin lockout coil. 

The buttons used are high quality industrial grade buttons.

It has a basic sound circuit and speaker that approximates the sound of running horses during a spin cycle. The volume potentiometer was bad and needed replacement. There is another small potentiometer for the "galloping speed" adjustment.

There are 2 payout tubes and the payout solenoids deal the coins in stacks of 5. The payout slide mechanisms needed a but of degreasing and a fresh re-lubrication.

Hidden behind the coin tubes there are three small stepper units that I suspect are for some mixer circuit and 4 toggle switches that are probably for payout percentages. The steppers advance one step each spin cycle.

Sadly, not having any instruction or schematics, I may never know their purpose for sure.

SO HOW DO YOU PLAY IT?

First insert a coin. Coin lockout solenoid then energises stopping you from inserting additional coins until a selection is made.

Yellow arrows light up to indicate selection choices. Press button under number 1 to 6 to select.

Once a selection in made additional coins may be deposited for more selections or to multiply potential payout of any selection so that each selection may have up to 3 coins wagered. With 6 selections thats a potential of 18 coins per play.

Once selections are made, press large button to start the spin cycle.

Spin section has two parts. One is to determine the payout (10, 20, 30 or JP (Jackpot is 100)) 

The other is to determine winning selection. The spin cycle can land on any if the 18 panels. Not just panels 1 to 6.

If the end of the spin cycle lands on a lit selection, you win. Maximum possible is 300 tokens. "Payout" panel is lit during payout cycle.

If you have any additional information or historical context about these early Japanese medal games please leave a comment.