By using relays, the signals for Video (Red, Green, Blue, Sync), Stereo speakers (L+, L-, R+, R-), and both of the optical guns (trigger and optical sensor) are able to be switched cleanly across both PCBs. On to the modifications! Hint: Lots of relays. Strike one against the idea of easily switching between PCBs in the same cabinet. As a consequence, it can be said that this JAMMA switcher fails to work as advertised. Unfortunately these missing diodes were intended to separate the video signals (Red, Green, Blue & Sync). But there is a problem, if you look closely at the spots between the pin connectors, there are spaces for eight diodes that are not installed. Since only one game is powered up at a time, the arrangement works. The two rows of diodes prevent signals from one PCB from from entering the opposing PCB. The remainder of the connections (video and control signals) are tied together from both PCBs to the cabinet JAMMA harness. The second relay alternates routing the speaker connection between the PCBs. This is not an issue since most PCBs do not use the -5v power feed. Note that this switcher does not switch the -5v signal between PCBs, instead it leaves those pins unconnected. The relay on the right of center alternates routing the +12v and +5v power feed between the PCBs. The basic theory of operation for this switcher involves using relays and diodes to switch back and forth between the two games when the button on the wireless remote is pressed. Let’s look at the switcher as it arrived: So how will this switcher handle that? Not very easily it turns out. In addition to the standard JAMMA harness, this cabinet also has extra connectors for the two optical guns and stereo speakers. Contol Inputs: Joystick (Up, Dn, L, R), Buttons (Shoot, Start), Coin Trigger, etc.Video: Red, Green, Blue, Sync and Video Ground lines.Power: +5v, +12, -5v (not used by most PCBs) & Ground.There any many different types of signals in play on a JAMMA harness. It standardized the pin-out on game PCBs and the associated wiring to components in the arcade cabinet. To make wiring a video game cabinet a standard practice so that a different game board could be swapped into a cabinet without changing the wires, the JAMMA ( Japan Amusement Machine and Marketing Association) connector was invented. It seems like it should be a straight forward task to switch between two game PCBs, but it is not. This was fine if just a little kludgy.īut it just so happens that there are products intended to solve the problem of switching all of the wires in the JAMMA harness between PCBs that sort of work. For years I got by just having the 2nd PCB mounted to a tray inside the cabinet and swapping the JAMMA and gun connectors when I wanted to switch games. Some point after I acquired it, I decided to purchase the PCB for the original Lethal Enforcers arcade machine for which I remember playing so much in the college dorm laundromat. Here is my Lethal Enforcers II arcade machine that I purchased many years ago. And what if you cabinet was a ‘gun’ game for which that type of arcade machine is at a distinct disadvantage for using with MAME type emulation? Well there ought to be a way to switch between multiple game PCBs right? Well yes there is, you can get a switcher for just this purpose… But, after implementing such a setup, I don’t recommend it. So here is the dilemma… You buy a video game cabinet and then decide that just having only one game in it does not satisfy your inherent need to make it contain more than one game.
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