Chroma/Luma Cable

Project: Chrominance/Luminance cable for video output.
Target : C64, C128, SX64
Time   : 25 min.
Cost   : <10 US$
Use    : Improve display quality; the picture will usually
         be crisp and you will never see those vertical color
	 stripes again where there should be just a plane color
	 area (like in the demo 'Krestology').

Summary

Cable which connects to the C-64's audio/video jack and to the chrominance and luminance jacks of your monitor. Additionally, it offers a SID output and a SID input plug.

Details

Most monitors have a jack for a composite signal. This signal comprises the color information, the brightness information and the synchronization signal. Since color and brightness are mixed on the cable, they interfere and cause color schlieren (streaks) on the monitor and when displaying certain patterns even vertical color stripes.
Many monitors have two jacks titled 'chroma' and 'luma'. Via these jacks the monitor gets the chrominance (color) and luminance (brightness) information on different wires, which avoids the interferences described above and adds a remarkable improvement to the display quality.

Ingredients

~1.5-2 m coax four-core cable, each core shielded
1 8-pin DIN connector (male), horseshoe shape
3 cinch plugs (male)
1 cinch plug (female)

Instructions

Disassemble the DIN connector and the cinch plugs.
Strip the wires at one end of the cable and solder one wire to each of the pins 1, 3, 5 and 6 of the DIN connector. (See step 4 for pin connection) Solder the shield of each cable to pin 2 (read: solder the shield of one cable to pin 2, then solder the shield of the other wires to the shield connected to pin 2)
Put the DIN connector's sleeve on the other end of the cable and move it to the plug so that it is ready for assembly. Do the same with the cinch plugs' sleeves.
Now strip the wires at the other end of the cable and solder each core/shield pair to a cinch plug (female for the AUDIO IN cable). Mark the wires attached to the cinch plugs with CHROMA, LUMA, AUDIO OUT and AUDIO IN according to the following scheme:
(Click here for ASCII version)
Connect the cable to your monitor and to the C-64's AV jack. Be VERY careful with the plug named 'AUDIO IN', the SID's audio input is very susceptible to overvoltage (>1V), which includes static electricity.
Adjust your monitor's input select switch(es) to chroma/luma input, if necessary; on the 1084 this mode is called LCA.
Switch your monitor and your C-64 on and see if it works correctly. If it does, try the AUDIO OUT by connecting it to your amplifier and running a program with music (game, demo). If you can, try AUDIO IN, too.
If your equipment has survived step 7, switch it off and pull off the cable. Assemble the DIN and the cinch plugs.

Possible failures

Monitor is in wrong input mode, e.g. Composite video.
Mixed up cinch plugs, especially CHROMA and LUMA.
Soldered wires to wrong pins on one or more of the connectors.
The figure above depicts the plugs from the SOLDER side.

Updated: September 23rd, 1997
Created: February 4th, 1997
Status : Verified on September 23rd, 1997