Sony KV (BG-3R) XA34M31

# Sony KV-XA34M31 (BG-3R) chassis CRT RGB mod

Below mod was performed on a 34" Sony KV-XA34M31 by Mark Robertson. BG-3S chassis is identical to BG-3R and the below RGB mod method can be applied to it as well.

This mod should also work on the following sets.

• KV-XA29M31
• KV-XJ29M31
• KV-XJ29M50
• KV-XJ29M60
• KV-XJ29M80
• KV-XJ29M81

This set supports composite, s-video and component natively. After the below modification, it also supports RGB via SCART input.

# CRT safety

READ THIS BEFORE CONTINUING

# Plan of attack

READ THIS TO PREPARE

# Theory

Sometimes it is nice to know the theory behind the mod. I have put this on a separate page. This shows how the various resistor values are calculated.

READ THE RGB MODDING THEORY

# Service manuals

• Sony KV-XA34M31 (BG-3R) Service Manual
• KV-XJ29M50, Sony KV-XJ29M60, Sony KV-XJ29M80 (BG-3R) Service Manual

# Specs

# Sony KV-XA34M31

• 220-240V, 50/60Hz, 185W, Manufactured in Malaysia
• Chassis: BG-3R
• Tube: Sony Trinitron A80LPD90X (Made in USA)
• Jungle Chip: CXA2159S
• OSD Chip: CXP750097-032S

# Performing the RGB mod

Now that you roughly know what needs to be done, prepare for the mod. Place the board on a comfortable place. Make sure you are not putting pressure on the flyback or other components. Taking out the chassis is fairly straight forward on this CRT. There are few wires that needs to be disconnected.

1. Degauss wire
2. Power wire
3. Ground wire attached to the neck board
4. Yoke deflection coil wire
5. Anode wire (this is the one with the rubber cap)
6. Left and right audio wires

Please remember that wires 1-5 are critical for the CRT to function and should not be omitted. Having any of these wires disconnected while powering up can damage the board and can have adverse effects.

It should also be noted, the B board (smaller board) should be removed to solder audio, sync and ground. The A board (bigger board) doesn’t need to be removed but does need to be on its side so you can remove the R063, R064 and R065 resistors.

# Mux diagram

# STEP 1: Remove the following components

Closed caption card (teletext) and OSD shares the same RGB input on the chroma. Therefore, this is not going to be a direct injection. It still requires the removal of the three (470Ω) ground resistors on the OSD side.

• R063 (470Ω)
• R064 (470Ω)
• R065 (470Ω)

# STEP 2: Connect RGB, Blanking and Ground

We are going to get rid of the closed caption (teletext) card and tap into the RGB input there.

The CN801 connector was salvaged.

R, G, B, Blanking and Ground wires were soldered to this connector.

The connector was reinserted into the board.

# STEP 3: Connect Audio and Sync

Soldered sync to the S-Video luma pin.

Note: S-video and audio dummy plugs are required for sync and stereo audio.

To permanently enable the luma input, you can follow the method Aidan Carter used on his Sony KV-XA25M31 set. In this setup, the blue wire connects the S-Video detect pin directly to ground. This effectively disables the composite input linked to the S-Video line. However, for most people with multiple composite inputs, this won't pose a significant issue.

# STEP 4: Build your mux board

Below mod uses the RGB mux board. This is optional, but will make your mod easier and stable. You can also create the circuit presented in the schematics above without the board. Please also checkout the precalculated resistor values.

Buy your RGB mux board

# STEP 5: Attach the female SCART connector to TV

Creating a SCART cutout and mounting it is an art. I have a dedicated section for it. How to create and mount a SCART female plug?

This SCART port was cut a bit rough. You can make the SCART port look smoother with a file.

# Horizontal Position Adjustment

In some cases, especially on larger screens, the picture will not be centered even after adjusting HPOS to 0 or to its maximum value. To get around this, you can try adjusting this lever, which will shift the picture horizontally.

# Games

Spyro The Dragon

Crash Bandicoot

# Patterns

240p - SMPTE

240p - Pluge

240p - Grid

240p - RGB

# Pictures

TV off

B Board

A & B Boards

Back Label

Tube