The internal wiring of an arcade cabinet is fairly straight-forward, but it can be a little confusing when building a MAME cabinet. My MAME cabinet requires +12v for the coin door lights, +3v for the trackball light, 110v for the fluorescent light, amplified speakers and PC. The monitor also requires 110v isolated from the line voltage.
My solution was to tackle the wiring piece by piece. First I picked up a new AC power cord. The ground and common wires were soldered to the old line filter. The hot wire was run through the old SPST switch, through a fuse block and into the line filter.
Output from the line filter was then run into the old isolation transformer. The monitor requires 110v, isolated from the source line to prevent electrocution and component failure.
To handle other devices such as a PC and amplified speakers, I connected an old power strip to the AC power source. I started by cutting the wall plug from the power strip and then soldered the wires to the previous wire installation. The power strip is connected directly to the source line instead of using fused and filtered voltage. The power strip itself contains this same protection.
By now the wiring starts to look rough but it's actually quite simple to trace. It's also easier to support new devices because I have a power strip mounted inside.
The last device I added was an old PC power supply. My original and final intent is to mount a PC motherboard directly to the cabinet. Having a PC power supply already in the cabinet will make this easier when the time comes. In the shorter term I'll just be sticking an entire PC in the cabinet. To mount the PC power supply, I turned it upside down and screwed it into place. I used a very short AC power cord to plug the power supply into a utility outlet that I soldered to the source line.
For now the PC power supply will be used to light the coin door buttons (+12v) and the track ball light (+3v). I thought about building a small linear power supply to handle this but the power supply was sitting around collecting dust anyway.
To make a clean connection to my monitor, I tracked down an old PC RGB cable that I had. The cable has 5 BNC connectors on the end for Hsync, Vsync and RGB. I built a small interface box with 5 female BNC connectors on it. The RGB cable plugs into this box. The box has 5 wires coming from it with alligator clips on the ends. Each wire corresponds directly to one of the inputs. Until the monitor connections are final, the alligator clips allow me to move signal wires around until I get everything correct.
I used the old monitor connectors and wiring harness. After tracking down the source wires and measuring a convenient length, I cut the wires and strip the ends. I clipped the corresponding alligator clips to each source wire.
Second Chance Arcade