Thursday 5 June 2014

Game recording straight from your cab: Home made, amateur solution.

If you've ever tried using a camcorder to record your game play while playing your favourite arcade game you'll know it doesn't always come out that well. As well as unusual refresh rates on your CRT monitor which make lines appear across the screen when recorded, you also have the problem of your button presses being louder than the sounds coming from the machine. You might also suffer from minor outbursts such as shouting expletives when things don't go your way.... just watch my Deathsmiles 1CC if you want to hear me swear.

For those above reasons I decided I would see if I could tap the lines on my cabs to make arcade games appear on a TV next to my cab as well as the cabinet monitor. Before you panic and think I would be going and making a mess of any of the harnesses on my cabs, fear not, no cabs were harmed in the making of this.

The parts used for this experiment are as follows:

1 JAMMA harness extender (so you're not soldering wires into your cab harness)
1 decent scart lead that has all the pins populated, not like the £1 piece of crap I bought off Amazon.
1 solderable breadboard
4x 330 ohm resistors
1x 100ohm resistor
1x 1k resistor
1x 10k resistor
3x 220uf 16v capacitors
~20m 18 awg multi core wire

Tools needed:

Solder
Soldering Iron
Wire Cutters/Strippers
Heat Gun
Heat shrinks
Screwdriver


First thing I did was to snip off one end of the scart lead with a couple of inches of cables still attached, then open it up, exposing the wires going into the pins. Chances are your scart lead pins will share wires from end to end for more than one pin. The one I used had 12 wires for 21 exit points, this is done by running the ground wires outside of the inner insulation of the active wires. For what we want to do, this wire is now useless. I decided to leave a small amount of wire running from each pin that would be soldered together with cable of my desired length. Attach wires to the following pins, those without anything written next to them can be ignored. To make sure the exposed wire doesn't make contact with another exposed wire and screw this all up, I used heat shrinks which form around the exposed wire under a few seconds of heating from my heat gun. Note: Pin 21 does not actually run inside the scart head, but into the metal surround to ground out.

My crap MSPaint image. Remember you are looking at this image from the solder side, not the front of the cable!:















Once the wires were cut, I went to the breadboard. The one I used is 30 holes across, by 12 high. The holes are set up in tracks of a row of 5 separated by 2 that each run the width of the board, then another track of 5. To make it simple I designated one column of holes on the board to each pin on the scart head. This rule will not be stuck to however later on in the build.

You now need to start applying your wires to the breadboard. Below is a diagram of how mine came out, I actually tested the video before I tried to get the sound wired in so you'll notice my "JAMMA side" ends up my "scart side" for the speaker wiring... doh! If you follow mine exactly if you're not entirely sure what you are doing it will work. If you do know what you're doing, then space them out more adequately and make it neater! Notice the +'s under the capacitors on the diagram. The longer leg (before you snip it!) is the positive. Make sure you do the soldering onto the copper side, the below image if only for illustration of the tracks.

Crap MSPaint image 2:




The end result of mine certainly isn't pretty....



But it is functional.....



In fear I tested this out on my home made bartop and a spare TV, just in case I'd rigged the power supply to blow by accident. I've got some DVD+RW discs on the way, so I'll have a go at recording some game play with my old DVD recorder I've got.

Updates to come.

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