A/V jack
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[edit] Description
The audio and different video signals are available on the A/V jack of the C-64. The output of the audio signal is available on a pin of the jack and can be fed seperately to the TV set, Monitor or stereo set. The video signal, that drives a TV set or monitor, can be picked up as "composite video" or "s-video". Beyond that, there is a audio input that is connected to the external audio input of the SID sound chip.
[edit] Pin Assignment
The a/v jack is a DIN jack with five or eight pins (both DIN 41524). The first C-64 models still had a five pin jack, like in the VIC-20. Shortly after that an eight pin jack was built in, providing the additional chrominance signal.
 five pin assignment |  eight pin assignment |
| pin | signal | notes | VC 20 | C128 |
|---|---|---|---|---|
| 1 | LUMINANCE | luminance, video y-signal, brightness | 6 volts DC, max 10 mA power supply of a rf modulator | like C-64 |
| 2 | GND | ground | like C-64 | like C-64 |
| 3 | AUDIO OUT | audio output | like C-64 | like C-64 |
| 4 | VIDEO OUT | composite video signal (mixed colour/brightness signal) | "VLOW" video low | like C-64 |
| 5 | AUDIO IN | audio input | "VHIGH" video high | like C-64 |
| 6 | CROMINANCE | chrominance, video c-signal, colour | - | like C-64 |
| 7 | - | not connected | - | like C-64 |
| 8 | - | not connected | - | 5 volts DC |
Notes:
The eight pin jack is not after DIN 45326 (pin arrangement: 270°), like indicated and pictured wrongly often, but after DIN 41524 (pin arrangement: 240°, horseshoe shaped). It's possible to forcibly plug in a wrong plug into the jack, but one should get the right plug in the first place on a new purchase.
On the VIC-20 the composite video signal is on pin four like on the C-64 or C-128. Additionally it is on pin five with a higher voltage level. Therefore a C-64 a/v cable that uses only pins 2, 3, 4 (ground, audio, video) can be used unmodified on a VIC-20 or C-128. Attention is advised when using a special a/v cable where incompatible signals could collide with each other.
Installation instructions for a second SID (stereo SID) often propose to use pin five (audio in) as the output of the right channel.[1]Though this is compatible with the pin assignment of stereo sets that used five pin DIN plugs in former times, it's not advisable. Due to the RCA plugs used nowadays, to use the not connected pin seven offers itself.
[edit] Signal Description
VIDEO OUT: video output
This is a video signal in the format of the analog TV signal before RF modulation. In the C-64 it is the standard format for PAL (most od the world) or NTSC (U.S.A./Japan). If a TV set has a video input it should be prefered over the RF signal, which loses quality by modulation in the C-64 and demodulation in the TV set.
Because the signal contains the information of the video brightness and colour it is named compostie video signal or CVBS (Colour Video Blanking Signal).
LUMINANCE: luminance, Y
This (TV-) signal contains all information necessary for monochrome video transmission. It consists of the brightness and synchronisation signals and therefore is called VBS (Video Baseband Signal)
CROMINANCE: chrominance, C
The chrominance (colour) is a part of the s-video signal (also Y/C signal). S-video is used in many montors and should also be prefered if using a TV set providing a corresponding input (seperate or on the SCART jack).
AUDIO OUT: audio output
maximum 2 volts audio signal, transistor coupled from the SID
AUDIO IN: audio input
This audio input (maximum 3 volts) is connected to the audio input (pin 26) of the SID sound chip. This signal is routed through the SID filters and/or output stage, depending on the programming. It is then put out together with the internally generated voices through the volume regulation of the SID on the audio output.
[edit] Pin assignment of s-video and Scart
Following is the pin assignment of the s-video and the SCART jack. This information should be sufficent to find or build a cable for any device configuration.
| 
|
| signal | C-64 A/V | SCART jack | s-video |
| ground | 2 | 4, 17 | 1,2 |
| audio | 3 | 2, 6 | - |
| video | 4 | 20/-* | - |
| luminance (Y) | 1 | -/15* | 3 |
| chrominance (C) | 6 | -/20* | 4 |
| * Only on Y/C-video over SCART. Not all devices with SCART connector support Y/C signals! | |||
[edit] References
[edit] Links
Usage of the Commodore video signal on the PC with frame grabber
