Sega Master System Model 2 RGB Video Mod Install Guide

This guide will show you how to get RGB video out of the Sega Master System model 2. It will be compatible with all stock Master System or Mega Drive 2 SCART cables depending on the output connector used. The guide covers both a passive RGB mod which will take the video from the console’s native RGB Encoder, and an active RGB bypass mod which will take the video from the console’s native Video Display Processor and “bypass” the console’s RGB Encoder.

Solder Maps

Sega Master System 2 – PAL / IC BD M4 Jr / 171-5922A

Sega Master System 2 – PAL / IC BD M4 Jr.PAL 2M / 171-6395A

Schematics

Sega Master System 2 – PAL / IC BD M4 Jr / 171-5922A

The schematic for SMS2 – PAL / IC BD M4 Jr.PAL M2 / 171-6395A uses the same part designations.

Sega Master System 1 – PAL / VA3 / 171-5535-10

Missing Components

When comparing the Audio/Video schematics for Master System 1 and Master System 2 the following components are missing.

  • 10uf/16v electrolytic capacitor followed by a ferrite bead on the audio line out from the RGB Encoder.
  • 75ohm resistor followed by a 100uf/10v electrolytic capacitor followed by a ferrite bead on the composite video line.
  • The Red, Green & Blue video signals are direct to the AV connector from the RGB Encoder.
  • 8pin DIN

Mod Pinouts

The mod is concerned with two ICs inside the Master System. The Video Display Processor and the RGB Encoder.

For a passive RGB mod, take the RGB signals from the RGB Encoder.

For an active RGB bypass mod, take the RGB signals from the Video Display Processor.

Sony CXA1145P RGB Encoder (171-5922A revision consoles)

  • Pin 23 for Red Video (Passive Mods)
  • Pin 22 for Green Video (Passive Mods)
  • Pin 21 for Blue Video (Passive Mods)
  • Pin 20 for Composite Video
  • Pin 10 for Composite Sync (Yes, from the C-SYNC IN pin). (Take signal from the 2.2K pull-up resistor.)
  • Pin 9 for Mono Audio

Fujitsu MB3514 RGB Encoder (171-6395A revision consoles)

  • Pin 23 for Red Video (Passive Mods)
  • Pin 22 for Green Video (Passive Mods)
  • Pin 21 for Blue Video (Passive Mods)
  • Pin 20 for Composite Video
  • Pin 10 for Composite Sync (Yes, from the C-SYNC IN pin). (Take the signal from the 2.2K pull-up resistor.)
  • Pin 9 for Mono Audio

SEGA 315-5246 Video Display Processor

  • Pin 27 for Red Video (Active Mods)
  • Pin 28 for Green Video (Active Mods)
  • Pin 29 for Blue Video (Active Mods)
  • Pin 30 for Composite Sync

Output Audio/Video Connector

There is a choice of two connectors to make the RGB mod backwards compatible with Master System 1 or Mega Drive 2 cables.

9-Pin Mini DIN (Through hole/Surface mount)

The use of this connector will require the removal of the RF box.

262 Degree “U-shape” 8-Pin DIN (Panel Mount version)

The use of this connector will require a hole cutting in the Master System case. Alternatively the RF box can be removed and the hole made larger.

SCART Cable Components

Details and schematic coming very soon

Consoles Unleashed RGB Mod Kits – Step-by-Step Install Guide

Remove RF Modulator

This can be done with a standard solder pump and a high soldering iron temperature.

Remove the RF modulator.
Six solder points will need clearing of solder.
RF modulator removed. No solder blocking holes.
Solder points all clean.

Make the Mount/Brace Assembly

Start by soldering the mount and brace together with the included turrets.

This can be done by hand, in a horizontal vice, or a pair of helping hands as shown here. Make sure the mount and brace are perfectly aligned and insert the turrets with the sharp point down then solder them in place. If the turrets are not straight, reheat whilst straightening.

Mount and brace perfectly aligned.
Turrets placed into holes as straight as possible.
Flux added to the holes.
Turrets soldered in place.

If doing it by hand, firmly grip the PCBs together making sure they are aligned. Then add plenty of flux to the turret holes. Solder the turrets in place by pre-loading the soldering iron tip with solder and applying it to the holes. The flux in the holes will allow the solder to flow and make a solid connection.

Attaching the Mount Brace Assembly

Once the assembly is constructed it can be placed into the holes left behind when removing the RF modulator.

Ready for the brace/mount assembly.
Brace/mount assembly in place.
Turret pins showing on bottom of motherboard.
Turret pins soldered in place.

Turn over the Master System mainboard and lightly solder in the turrets. Only do it lightly so the position can be easily adjusted later if needed. If confident it is aligned perfectly, it can be soldered in fully.

Adding the 9-Pin Mini DIN

9-Pin Mini DIN in place.
9-Pin Mini DIN soldered in place.

Add lots of solder to the three pads that surround where the connector will be placed.

Place the connector into position. Make sure the connector is sitting flat.

Using a high soldering iron temperature, reheat the solder and simultaneously heat the side of the connector. The solder should eventually adhere to the connector. Do this for all three sides.

Once the connector is secure the position of the entire assembly can be adjusted to align correctly with the hole left by the RF modulator. Fully solder the four posts once the position is good.

Attaching the Hood & Wiring

Add the Hood PCB and then wire up the connections shown on the solder map for the type of RGB mod used.

Passive RGB video hood placed onto the 9-Pin Mini DIN.
Passive RGB video hood wired up.
Electrical tape added to RF shield to prevent shorting with the passive RGB video hood.
9-Pin Mini DIN is perfectly aligned.

A square might need cutting from the RF shield directly above where the Hood PCB is located or some electrical tape can be adhered to the RF shield to prevent the RF shield shorting with the Hood PCB solder connections and components.

Plug In and Test

Plug in a Mega Drive 2 RGB SCART cable and be astonished at the glorious RGB video signal displayed on the telescreen.

Sega Master System 2 Passive RGB video as displayed on a CRT.
Sega Master System 2 Passive RGB video as displayed on a CRT.