Sony RGB Encoder
S-Video & Composite A/V Circuit (C945 Based)
This circuit reduces the component count of the old style 1815 circuit and features better color and better compatibility with modern HDTVs.
- Parts List:
- C1: 220uF, 6.3v electrolytic (chroma)
- C2: 220uF, 6.3v electrolytic (composite video)
- C3: 10uF, 6.3v electrolytic (mono audio)
- T1: C945 (2SC945, KSC945, etc)
- VR1: 500Ω - 2kΩ Potentiometer (luma)
- VR2: 500Ω - 2kΩ Potentiometer (chroma)
- VR3: 500Ω - 2kΩ Potentiometer (composite)
Try to connect your +5 and GND as closely as possible to the CXA1145 to avoid ground loops.
In the provided schematic, analog ground (Pin 1 & 24) as well as +5 (Pin 12) are shown.
- For the variable resistors, common starting values are:
- VR1: 33Ω
- VR2: 75Ω
- VR3: 75Ω
By using potentiometers instead of fixed resistors, you can tune the device to look best on your display.
The connection for monaural audio is shown. Stereo audio is system dependent.
S-Video and Composite Video Mod PCB install notes
Support for this product
Once assembled, the following connections to your console are required:
- S-video Connections to the console:
- Y-in: CXA1145 pin 16
- C-in: CXA1145 pin 15
- +5v: CXA1145 pin 12
- GND in: CXA1145 pin 1
- S-video at the solder side of the jack:
- 1 & 2: GND out
- 4: Y-out
- 3: C-out
- Composite pass-through option:
- V-in: CXA1145 pin 20
- V-out: RCA jack center terminal, RCA jack ground to GND out
- Mono-in: CXA1145 pin 8
- Mono-out: Mono audio RCA jack
DO NOT USE: Historical Circuit: S-Video Buffer Circuit (2SC1815 Based)
Providing this for posterity. DO NOT USE THIS CIRCUIT!
- Parts List (Build twice - once for luma, once for chroma):
- R1: 10k
- R2: 10k
- R3: 110k
- R4: 110k
- C1: 100uF, 6.3v (or higher) electrolytic
- C2: .1uf ceramic
- T1: 2SC1815*
- VR1: 500Ω - 2kΩ Potentiometer
*An NTE85 is frequently cited as the transistor for this circuit. NTE typically makes substitute parts, not original parts. NTE85 is the replacement for the 2SC1815, except the NTE part is about 20 times the cost.