Sony (BG-1L) KV-LX34M31

# Sony (BG-1L) KV-LX34M31 CRT RGB mod

The Sony KV-LX34M31 is a massive, highly sought-after 34" curved CRT television featuring a legendary Super Trinitron tube. Renowned in crt collection community for its superb geometry and vibrant color reproduction, this BG-1L chassis TV is famous for its built-in subwoofer and excellent picture quality.

View full CRT details and more mod examples →open in new window

# Contributors

Thank you to everyone who contributed to this guide:

• Mark Robertson — contributor, RGB mod and pictures

# CRT safety

READ THIS BEFORE CONTINUING

# Plan of attack

READ THIS TO PREPARE

# Manuals and Datasheets

• Sony KV-LX34M31 Service Manualopen in new window
• Sony KV-LX34M31 Service Manualopen in new window
• Sony CXA2050S Datasheet (Jungle)open in new window

# Specs

• Format: PAL, PAL60, SECAM, NTSC3.58, NTSC4.43
• Chassis: BG-1L
• Tube: Super Trinitron Tube A80JYV51X
• Jungle Chip: Sony CXA2050S
• OSD Chip: Sony CXP85332A-238S

# Schematics

# RGB mux diagram

Prepare the mux diagram. If you are building your own circuit, this diagram should help.

# Performing the 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, on this CRT, you can do the RGB mod by just taking out the A board. This means you don't even need to remove the anode wire.

# Mux diagram

If you are building your own circuit, this diagram should help

While a second set of RGB input is available on CXA2050S, unfortunately on the BG-1L chassis it is disabled in software. There are I2C hacksopen in new window that can potentially enable this input. However, we don't need to take this harder path. We can simply do a mux mod, which gives a stunning RGB picture.

# STEP 1: Remove the following components

Remove the three (1.8 kΩ) ground resistors. These are marked as Cxxx for whatever reason instead of Rxxx.

• C325 (1.8 kΩ)
• C326 (1.8 kΩ)
• C327 (1.8 kΩ)

# STEP 2: Connect RGB, Blanking and Ground

Replaced jumpers JW134, JW135, JW136, JW137 with diodes. Diode stripes should be pointing towards the chroma chip. The idea here is to make sure the external RGB input currents don't go towards the OSD chip. Instead these diodes make sure the current is directed towards the chroma IC (CXA2050S).

Red, Green, Blue, Blanking (Brown), Ground

# STEP 3: Connect Audio and Sync

For stereo audio to work, both Video 1 audio left and right inputs should be populated. There is a physical switch inside the red RCA audio port that enables stereo. For sync to work through luma, S-Video port should be populated. When the S-Video port is populated, detect line is grounded signaling the video switch IC to use chroma/luma input instead of the composite video input.

# STEP 4: Build your mux board

This 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 mux calculatoropen in new window to play with your own values.

Compatible mux boards:

• RGB MUX BOARD KIT 1.4Bopen in new window

Buy your RGB mux board kit

# 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.

# Games

PS1

PS1 - Spyro The Dragon

# Patterns

Pictures taken before HPOS adjustment

# Pictures

A Board

Back

Back Label

Tube

# Pictures

See more photos and contributions →open in new window