C64 S-Video cable – the easy way, and with no SCART

I made another C64 S-Video cable for a fellow Commodorist. Instead of using SCART, this time I made the cable as an actual S-Video lead, which admittedly is more universal than the SCART connector. Also this way it doesn’t take that much effort to make the cable.

This time I present you step-by-step instructions on how to make the thing. For more theoretical approach and details about the wirings and components, check the other post where I made the SCART cable.

I think the best and easiest way to make a cable like this is to use an ordinary S-Video and audio leads. And that’s what we’re going to do here.

Here’s what we need. An S-Video lead, an ordinary audio cable with RCA male connectors, an 8-pin DIN plug for the C64 Video port (check the other post for connector type details) and a 330 ohm resistor. Additionally you might need some heat shrinking tube, and of course, a soldering iron plus some solder, and tools for wire stripping and cutting. Not to forget a continuity tester or multimeter.

By the way, paying some attention to the DIN plug quality is worthwhile. The better ones have pins that are hollow inside, like small tubes. It’s much easier to solder the wires into those than onto pins that are solid, and only have a shallow pit on them.

First, cut the S-Video and audio leads to desired length. If you didn’t spare on the cable lengths, you have the leads for to two cables, woo!

Then, if you do like I did, and tie the video and audio leads together using stubs of heat-shrinking tube, slide them on the cables now, before doing anything else. Also the DIN plug cover should go there at this point!

Next, strip the wires. Then use your continuity tester or multimeter to determine which wire is which in the S-Video lead. There are two ground lines and one wire for Luminance (intensity, “brightness”) and one for Chrominance (colour). S-Video plug pinout you’ll find e.g. on the Wikipedia page. Don’t get mixed with male and female pin arrangements!

In my lead, blue and yellow wires were ground – which is for chroma/luma doesn’t really matter, as there is only one common ground point available in the C64 video port. Green wire was luminance and red chrominance. Apply solder to the exposed wires, and attach the 330 ohm resistor to the chroma wire. Notice how the chroma wire, the one with the resistor, is a bit shorter that the others. This helps in putting the connector together later on.

Now the wires have been prepared. Video ground wires are tied and twisted together, like the audio cable shielding.

Next I’ll be using this ingenious fork pin to connect the ground wires into it! Why? Because the fork pin doubles as a connection between DIN plug pins 2 and 5 and makes it easier to solder the wires onto the plug.

And why am I connecting pins 2 and 5 together you wonder? Because that’s a simple yet effective noise reduction mod for your Commie! Pin 2 is the ground pin, and pin 5 is audio in. Read on about the details on that other post.

You can prepare the fork pin from e.g. cut resistor lead. Prepare it so that you can just insert it onto the pins 2 and 5 of the DIN plug.

Here we have all the cable wires ready to be soldered onto the DIN plug.

Let’s start with audio wires. A stock C64 outputs mono audio, so we solder both audio wires to pin 3, audio out. In case you happen to have a stereo-SID setup, the otherwise unused pin 7 can be used for the second (right) audio channel. Why pin 7? Again, check the other post.

By the way, I found out I could use a desoldering braid package to hold the DIN plug firmly in place while soldering. Best discovery in ages!

Next up the chroma line, the one with the resistor. Insert and solder the resistor lead to the pin 6 in the middle of the plug. I also put some heat shrinking tube around the chroma resistor to avoid any risks of shorts inside the plug.

Then the luma wire to pin 1, piece of cake!

Finally, the ingenious fork pin into it’s place. Push it all the way in and secure with solder.

Now that all the wires are soldered in place, make sure there are no shorts between them. Then the plug can be put together. If possible, the tinfoil or wire shielding found in S-Video and audio leads can be connected to the metal frame of the DIN plug. You can e.g. bend them backwards and squeeze them under the metal part that extends from the plug frame and holds the cables firmly so that there is no strain to the wires itself.

Lo and behold! It’s a brand new S-Video cable for the C64!

As a nice surprise, the image quality is even better with this cable than with the previously made SCART cable. The discussed checkerboard pattern is much lesser, almost gone, and the picture is more stable. I’m not sure what makes the difference, but it might be because now I’m using an actual separate S-Video cable instead of a generic signal cable. Less signal cross talk maybe? Also the chroma resistor is now located right at the C64 video port and not at the other end of the cable.

Anyhow, the output is very satisfactory! Now go make yours.

Some comparing shots

The following photos have taken from the same plasma-TV than the previously taken picture quality shots. Once again the pictures are otherwise unmodified, but this time I have re-saved them with lower jpeg setting to cut some excess file size. I’ll  post these pictures as-is, for those who are curious.

First up, the DIY S-Video cable we just made:

Now, the previously made SCART AV cable in S-Video mode:

Then, for comparisons sake, an S-Video cable I have bought years ago from an on-line shop that sells all sorts of Commodore items. This cable is very similar to the DIY cable described in this post, and probably build using the same principle. But, this cable does not have any resistors nor noise reduction mod for the audio. However, the picture quality is almost identical to the DIY SCART cable above:

Please note that the left image looks smoother than it is due to slightly shaken camera…

And as a bonus, the DIY SCART cable in composite video mode: