Atari Jaguar RGB Upgrade
The Atari Jaguar produces analogue RGB on its rear A/V connector as standard, so getting an RGB picture needs a suitable cable or adapter and no work inside the console.[1] For the A/V port, Atari's user's guide lists a Composite Monitor Connector and an S-Video Connector as optional equipment.[2]
What the console provides
[edit | edit source]On Atari's schematic the 8-bit red, green and blue outputs of the video DAC (U7) are buffered by three MMBTA14L transistors (Q2, Q3 and Q4) and leave through 75 Ω series resistors (R29, R34 and R43) and ferrite beads to the A/V connector. The same signals feed the MC13077 encoder (U3) through 1 µF capacitors, and the encoder produces the composite and S-video outputs. The A/V connector is a 24-way edge connector (two rows of twelve, P1A and P1B on the schematic) that also carries composite video, S-video luma and chroma, the left and right audio channels, sync, and the 9 V supply through a 100 Ω resistor (R83).[3]
Making a cable
[edit | edit source]RetroRGB gives this wiring for a home-made RGB cable, from a diagram published by Atarimax:[1]
| Signal | Pin |
|---|---|
| Red | 4B |
| Green | 7A |
| Blue | 5A |
| RGB ground | 10B |
| Composite sync | 5B |
| Audio ground | 2A |
- Use a 24-pin dual-edge connector on a 0.100-inch pitch.
- Put a 680 Ω, 1/4 W resistor and a 220 µF, 16 V capacitor in the sync output. RetroRGB found no components needed on the colour lines.
- Keep audio ground separate from video ground.[1]
Atari's schematic agrees for the row it labels P1B: red on pin 4, the sync line on pin 5 and video ground on pin 10.[3] Check the remaining pins against the schematic before soldering.
Ready-made cables and adapters
[edit | edit source]- RGB SCART cables for the Jaguar are made with either a clean composite-sync line or sync taken from composite video. VideoGamePerfection tested Retro Gaming Cables' clean-sync version in 2015 through an Extron switch that will not work without clean sync, and reported no dropouts.[4]
- Humble Bazooka's Jag2Gen converts the A/V port to the Mega Drive 2 (Genesis 2) mini-DIN, so any Genesis 2 cable, RGB SCART included, can be used.[5]
- Humble Bazooka's JagAIOA adapters break the port out to every output at once. RetroRGB reports that the first version, which passes the signals straight through, gives a dimmer picture than expected through Genesis 2 cables, because those cables contain their own circuitry. The later "Amp'd" version adds a THS7374 video amplifier to the RGB lines and runs composite video through its spare channel, so RGB and composite can be used at the same time.[6]
PAL and NTSC consoles
[edit | edit source]The MC13077 encoder's PAL/NTSC input is set on the board, with R19 marked "0R NTSC only", and a configuration resistor (R140, on input B4) tells the software whether the console is PAL or NTSC.[3] These settings change the composite and S-video encoding; the RGB outputs come from the DAC before the encoder.
Related pages
[edit | edit source]- Atari Jaguar
- Atari Jaguar General Maintenance
- Atari Jaguar Troubleshooting Guide
- Atari Jaguar Documentation
References
[edit | edit source]- ↑ 1.0 1.1 1.2 RetroRGB, "Atari Jaguar": native RGB output, cable options and the "Make Your Own Cable" wiring, with a diagram from Atarimax.com. Community source.
- ↑ Atari Corporation, Jaguar 64-Bit Interactive Multimedia System User's Guide, P/N 500339: connection to a composite monitor (p. 9) and to a monitor with S-video (p. 10), and "Optional Equipment" (p. 13). Hosted here as File:Atari Jaguar User's Guide (500339).pdf.
- ↑ 3.0 3.1 3.2 Atari Corporation, SCH. Jaguar Console, document 500162 Rev. 5.3, 21 September 1993: video DAC U7, buffers Q2-Q4, encoder U3, A/V connector P1A/P1B, R83 and the configuration resistors. Hosted here as File:Atari Jaguar Console Schematic 500162 Rev 5.3.pdf.
- ↑ BuckoA51, "Atari Jaguar Clean Sync SCART review", VideoGamePerfection.com, 23 February 2015. Retailer review.
- ↑ RetroRGB, "Use Genesis A/V Cables on a Jaguar", 24 May 2023. Community source.
- ↑ RetroRGB, "JAGAIOA: Amp'd Edition", 25 February 2022. Community source.