I wanted to share some info about a new C64 gadget I stumbled over on eBay. It's a neat little AV breakout board for the C64. I got it from Retro Fuzion, an Australian-based eBay vendor. These board are sold by a lot of vendors, but I liked the 3d-printed casing and the labelling of this one:
The A/V-Adaptor allows to connect standard S-Video and Audio or Composite-Video cables to the A/V-Jack of the Commodore C64. A 330 resistor to attenuate the Chroma signal for S-Video is installed, but it can be deactivated by setting a jumper (JP2). This attenuation is required, since the chroma signal has a level, which is too high for standard S-Video.
Further, the audio input can be connected to GND, in case it is not in use to reduce the noise introduction.
The two audio output jacks can be connected by a jumper. Alternatively, the stereo sound output (A/V-Jack, pin 7, in case a 2nd SID is installed inside the C64) can be connected to the right channel of the audio output. The first SID output is connected to the left channel of the audio output.
Connectors:
A/V-Plug
The A/V-Plug for the C64 is the inner part of a Lumberg 033099 SV 80 DIN-Plug (8 pins, horse shoe = 262°). It provides a round plastic shell of the DIN-connector and long enough pins, so the adaptor can sit firmly in the A/V jack. The inner part of a cheaper (standard) connector cannot be used, since it does not sit firm enough.
Pin Signal
1 Luminance
2 GND
3 Audio Out (mono/left)
4 Composite Video
5 Audio In
6 Chrominance
7 Audio Out (right – if provided)
8 -
S-Video Jack
A vertical PCB mount Mini-DIN jack (4 circuits)
Pin Signal
1 GND (Luminance)
2 GND (Chrominance)
3 Luminance
4 Chrominance
RCA-Jacks
- Audio Out (mono/left)
- Audio Out (mono/right)
- Audio In
Composite Video
Jumpers:
Chrominance HI
The chrominance signal has a too high level for the standard S-Video chroma signal. The jumper bridges the 330 resistor (R1) to switch off this attenuation.
Status Configuration
- open Attenuation active
- set Attenuation inactive/off
Audio Input
To reduce the noise introduction to the Audio Input, this can be grounded.
Status Configuration
- ON SID Audio In connected to
- OFF SID Audio In connected to GND
Mono/Stereo
The standard audio output of the SID is one channel (mono). In cases a 2nd SID is installed, the 2nd audio output is (usually) connected to Pin 7 of the Audio/Video jack of the C64. JP3 connected the right channel of the audio output (J4) to either J2, Pin 3 or Pin 7.
Status Configuration
- MONO J4 connected to J2, Pin 3
- STEREO J4 connected to J2, Pin 7
