Introduction: ColecoVision Composite Video
Like all other consoles of the time, it uses RF out. The easiest way to connect it to a modern television is to use an RCA-to-RG6 adapter. This plugs into the coax on the back of your TV (incidentally, you can actually use your ColecoVision or Atari as an antenna for your television).
The quality is pretty poor by modern standards, though. You usually get a fairly noisy picture. 30 years ago we all had smaller TVs and were used to low-quality visuals. It looks very bad now.
So let's upgrade one to use composite video! Composite isn't nearly as good as HDMI, component, RGB or even S-Video, but it is still much better than RF. This is also a pretty easy project; it's a good one to get your feet wet once you feel like you are okay at soldering.
Finding good documentation for doing this is a little tough. There are also some big catches with most versions I've seen. If you do the audio mod incorrectly, the Expansion Module #1 (which allows you to play Atari 2600 games on the CV) will not have audio. This is obviously not preferable. Even if you have no plans to use the module, doing the audio wrong will also mean audio doesn't work on RF out. I don't like the idea of removing perfectly good functionality from a console when modding it. So we're going to do this the right way.
I based most of this on instructions by Ben Heck. It's essentially the same mod, with three differences:
- I used a TRRS jack rather than 3 RCA jacks. That means I only have to drill one hole in the console.
- I assembled the circuit on a PCB rather than soldering the components directly to the ColecoVision.
- I took the audio from a different point. The way I did it is easier, less destructive and most importantly, allows audio to work when using Expansion Module #1. RF out audio also still works with the method I use.
Step 1: Tools and Materials
- TRRS jack
- TRRS A/V cable
- Drill with 1/4" bit
- 2N4401-ND transistor
- 1k resistor
- 1k potentiometer
- Electrical tape
- Soldering iron, solder
- Small PCB
- Hot glue gun
A TRRS jack is similar to a mono or stereo jack. A mono jack has 2 contacts: audio and ground. It's a Tip and Sleeve connector, or TS. Usually the tip is audio and the sleeve is ground. A stereo jack has 3: audio left, audio right and ground. It's a Tip, Ring and Sleeve connector, and usually the tip is audio left, the ring is audio right and the sleeve is ground.
You can see where this is going. A TRRS jack has four connectors: Tip, Ring, Ring and Sleeve. This allows for 3 connectors plus one ground, which means we can also include composite video. You've probably come across plugs and jacks like this on camcorders or smartphones.
It appears that most cables are configured so that the tip is audio left, first ring is video, second ring is ground and sleeve is audio right. I'm not sure why the sleeve isn't ground, but hey. Whatever works.
Why use a jack like that instead of the normal RCA jacks? I just prefer to do as little modification to the case as possible. It's bad enough that I'm drilling even one hole. And if I later decide I want to just use RCA, I can drill more holes.
That said, these aren't the easiest jacks to find. You're not going to find them at Radio Shack, anyway. Just google around. I found some at showmecables.com. YMMV. If you can't find any or you don't like the price, feel free to do a standard Yellow White Red set of RCA jacks. It's the same idea; just remember to ground each one. Alternatively, you could use a normal TRS jack and just run video and a single audio line. The ColecoVision has only mono anyway, with TRRS we're just sending the same signal to Left and Right.
Anyway, you'll also need a TRRS -> RCA cable. I had a couple lying around. I have a Monster one that I probably bought 10 years ago. You can buy them at any electronics store or on the web. Just google "camcorder cable". Most of them should be wired as explained above, but you should definitely check first. I'll cover that later.
The rest of the items should be self explanatory. I'd recommend a small PCB as well. I used a tiny circular one from Radio Shack. You can solder the transistor, resistor and pot directly to the RF daughterboard, but I opted to solder them to a PCB and run wires to the daughterboard. Whatever floats your boat.
Step 2: Open the ColecoVision
I've already done an instructable describing how to open and clean a ColecoVision, so read that for instructions. Opening a ColecoVision is a bit tricky, so definitely check it out.
And you should probably clean this sucker. Seriously. If it hasn't been opened for 30 years, there are probably some horrible, nightmarish things in there that you don't want in your home. Send your loved ones on a day trip, make sure you're up-to-date on your immunizations, put on your HAZMAT suit and purge this thing of its horrors.
Step 3: Soldering the Circuit
We're going to make a very simple circuit. I'm not entirely convinced that this is the best circuit to use (though it works fantastically), which is part of the reason I opted to use a separate PCB and run wires. If I decide later to try something else, it will be easy to remove this.
What we're going to do is two things: amplify a composite signal with a transistor and tap into audio out.
There's nothing to stop you from breadboarding this first. I decided not to, since it only involves three components, but feel free to if you're more leery.
See the schematic. A brief run-through: Wipe of potentiometer gets +12V. One leg goes to transistor's collector. Base of transmitter goes to Pin 13. Emitter goes to video out; also to 1k resistor which goes to ground.
Meanwhile, just run audio out from the marked solder point.
When you're done soldering the PCB and all wires are connected, put some electrical tape or hot glue on the bottom to prevent any shorts.
Next, solder the outputs to your jack. How do you know what terminals to solder to? The easiest way to tell is to use a multimeter to test continuity. Plug the TRRS cable into the TRRS jack and check to see what terminal connects to which connector. Be sure to find Ground as well.
Check and double-check those connections. Draw a diagram if you have to.
Then solder them up. Composite and Ground come off the PCB. The audio comes straight from the board. I ran two wires to do 2 channels of audio. You can probably run one wire and solder it to the Left and Right terminals of the jack for the same result.
Step 4: Test
Considering what a pain the ColecoVision is to open and close, now is a fine time to test the A/V out. Plug it into a TV, plug in the power, put a cart in and turn it on.
If you're getting a poor picture or no picture at all, try adjusting the potentiometer until it looks good. If it still doesn't work, go back and double-check that everything is correctly soldered. Check for any possible short-circuits.
Step 5: Install A/V Jack & Finish
When you're satisfied with the video and audio, mount the A/V jack then close the sucker up. You may want to use electrical tape to route any wires that may stray near the cartridge slot.
Drill a 1/4" hole in spot that will allow the plug to fit. Then mount the jack in whatever way it is supposed to. Mine used a nut to hold it in place.
Close the console up, replace the screws and you're good to go! If you really want to bask in the greatness of this upgrade, go ahead and switch between composite and RF. Force your friends and family to watch. Demand they be awed. Then apologize profusely, because that was a pretty rude thing to do.
Some final notes:
If I were to do this again, I might opt to not use a PCB and just solder the components directly to the RF board. It's such a simple modification that a PCB is a little overkill. I'd also use much shorter wires, and possibly better-shielded ones, though they haven't given me trouble yet.