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Simplifying the Interface

Using the Coin Door Buttons for MAME "Coin-up" Functions


During my recent MAME cabinet buildup I was confronted with the typical options; what should it look like? How many players? What controls should I use? When I finally narrowed down all the decisions I decided that I wanted to create a cabinet that was both attractive, not ostentatious, would look like a piece of furniture, and was simple to operate. In order to make it easy to operate I tried to minimize the choices an operator would have to make, simplifying their game playing experience.

When viewing a 4-player console with joysticks, flight-sticks, trackball, and spinner plus all the accompanying buttons I decided to try to reduce the number of buttons and those that I did use to make there purpose easily distinguishable. To that end I made a few changes.

  1. I decided to label the control buttons by burning the button functions into the wood.
  2. I moved the coin-up buttons to the eject buttons on the coin box.

Burning the Instructions

Burning the words, Select, Pause, Exit, and Shift into the console makes is easy for a player to figure out how to get about with the GameEx interface.

Console after burning in the labels

Although some of the buttons share the same key assignment such as Player-1 Button-1 and the button labeled Select, I think that the overall user-friendliness is greatly improved.

Coin Door Coin-Up

The second thing I did was wire up my Coin Door so that by activating the coin return it triggers the micro switch to add credits as if a coin were actually deposited. I used Custom Labels to indicate which player was for which button.

The front of my coin door with player labels in place

Further, by following the directions below I was able to retain the original functioning of the coin acceptors. Occasionally a coin will stick but this can be resolved by sanding the edges of the swivel ball link, in the meantime I hit the door with my hand (well not only does it work but it gives me the nostalgic feeling of the day’s that a quarters would get stuck because someone crammed a pop-top in the slot). Being that I am still trying to complete my cabinet I have not had the time to tweak it yet.

Overview of the linkage installed

Converting the Switches

You can find the parts at the following links:

Note: I purchased equivalent parts locally and can only assume that these parts will work the same.

Each coin slot requires the pictured pieces

Route out this hole

Using a Dremel tool with a small cutting bit, route out a grove in the top edge of each eject button swing arm (white plastic piece). The position is based on trial and error, the placement of the pictured hole was the location that seemed to provide a significant amount of throw but not so much as to push the bottom ball link off the switch wire. Before cutting this hole study the mechanical action of the switch.

Screw the nylon clevis onto the push rod and attach it to the hole you created
Note: By Screwing the white clevis, you are able to fine tune the slack adjustment

Now you need to look at making that linkage reach the micro switch in a manner that will not interfere with any of the mechanics’.

Remove the linkage, using two pairs of needle-nose pliers begin to bend the linkage in a manner which will allow it to not interfere with any of the mechanics’ of the switch assembly yet allowing it to end precisely at the micro switch. This is trial and error; I would recommend making one bend at a time, attaching it, checking it, removing it, and then go on to make the next bend.

First Bend in linkage

Top view of clevis linkage

Bottom view of swivel ball link

Depending on the type of pushrod used, you may not have threads at the other end as it was for me. I used the Dremel tool, drilled out the swivel ball link threads, used a drop of superglue, and slid the end on the rod.

Close-up of the swivel ball link

The above picture shows a close-up of the swivel ball link, the red arrow indicates where the occasional snag can occur preventing a coin from passing easily. The bottom of the swivel ball catches on the edge of the switch. This is a simple matter of tweaking it with a bit of sandpaper or by using some tape to prevent it from catching the lip of the switch.


Alternative Solution: Optical Coin Switch Detector

Well I hope this was either entertaining or informative, or both. Good luck!



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