C64 A/V cable – theory and practice

March 30, 2012

A while ago I made a proper SCART cable for Amiga, so why not for C64 as well? So what I did was a C64 SCART cable with selectable composite/S-Video mode, including a ‘chroma fix’ and audio noise reduction ‘mod’ plus a preparation for possible stereo audio use. But let’s start with the theory.

Cable making principle

Building an A/V cable for C64 is not very difficult. In the simplest form, what is needed are plug for the C64 Video port, a cable with enough wires for the desired operation and the output connector(s).

C64 Video port

The C64 Video port is an 8-pin DIN connector, which is a standard multi purpose connector. It means that the required DIN plugs are easy to find and cheap. However, there are two different versions of the 8-pin DIN plug. The two versions differ in the shape of the arc that the pins form. Best shown as a picture:

The two pins marked in grey in the wrong type DIN plug will prevent the plug from being inserted into C64 A/V jack. But not to worry in case you’re holding the wrong type of plug in your hand, these two pins can be cut off or pulled out from the connector plug. In any ordinary A/V cable they are not needed anyway. Here is the Video port pinout:

Some early C64s had a 5-pin Video port that are missing the pins 6-8. It means there’s not separate chroma signal available there. In other words: no S-Video, only composite available via the video port.

Make note on the pin 8. It is either directly wired to the +5V DC line from the PSU (after the power switch) or not connected. According to my first hand research, the +5V DC line is present in the C64 Video port in all but the earliest two models. The +5V line is present starting from model C64B, or motherboard ASSY-NO. 250425. That means machines manufactured starting from 1984. Read the rest of this entry »

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