Sony (BA-4D) KV-20S42

# Sony (BA-4D) KV-20S42 CRT RGB mod

The Sony KV-20S42 is renowned for its 20-inch viewable size and classic 4:3 aspect ratio, making it an excellent choice for retro gaming and vintage media enthusiasts. Manufactured in Mexico, this model features the iconic Sony Trinitron tube, known for its vibrant color reproduction and sharp image quality.

Equipped with the BA-4D chassis, the KV-20S42 supports RGB input via a mux method and allows for component input through direct injection, providing flexibility for various connectivity options.

The display's chroma is powered by CXA2133S/CXA2133BS chips. With its robust build and modding potential, the Sony KV-20S42 stands out as a reliable choice for those looking to enjoy classic video games and media in their original format.

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

The RGB mod for the Sony KV-20S42 is fairly simple and makes a noticeable improvement on this composite-only set. Additionally, the KV-20S42 can be modified for component input as well. For this mod, I also decided to permanently enable stereo sound. Interestingly, it's possible to add an S-Video input if you can find the right connector, though I plan to tackle that at a later time. You can also follow this older tutorial which has additional pictures.

Instructions below should also apply to these models:

• KV-13M42
• KV-20M40
• KV-20M42
• KV-20S42
• KV-20S43
• KV-20S90

# Contributors

Thank you to everyone who contributed to this guide:

• Suntharopen in new window — showcase author

# CRT safety

READ THIS BEFORE CONTINUING

# Plan of attack

READ THIS TO PREPARE

# Manuals and Datasheets

• Sony KV-20S42 Service Manualopen in new window
• Sony KV-20S42 Service Manualopen in new window
• Sony CXA2061S Datasheet (Jungle)open in new window
• M37273MF-252SP Datasheet (OSD) — Available for Pro Users only. See CRT detailsopen in new window for access.

# Specs

• Manufactured: Mexico (1999)
• Chassis: BA-4D
• Tube: Sony Trinitron A51LML50X
• Jungle Chip: Sony CXA2061S
• OSD Chip: M37273MF-252SP
• Screen Size: 20"

# 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.

Sometimes it can be overwhelming to see a large chassis. But, we are primarily going to focus on two areas.

• Area A: This is where we are going to remove resistors and attach the R, G, B and blanking wires
• Area B: This is where we are going to connect composite, audio L, R and ground wires

# STEP 1: Add RGB inline diodes

I recommend using this method for all KV-20S42 mods to minimize interference. You'll need to lift one side of resistors R025, R026, and R027, and add diodes. The side of the resistors you lift and the direction of the diodes are crucial. If done incorrectly, the OSD will not function. Be sure to follow the instructions and pictures provided carefully.

Also, adding didoes means you will need to use 1KΩ resistors on the RGB mux board.

# STEP 2: Remove resistors and attach R, G, B wires

Zooming in on Area A before removing the resistors.

Remove the following components. RGB resistors to the ground. Please always measure and mark them, so that you know you are removing the correct partrs.

• R087 (680Ω) Green ground resistor
• R088 (680Ω) Blue ground resistor
• R089 (680Ω) Red ground resistor

Then attach the R, G, B and blanking wires to the respective legs of the diodes. Wires should be attached to the side closer to the jungle chip.

R, G, B wires are red, green and blue respectively Brown wire here is used for blanking

# STEP 3: Permanently enable stereo

This is a relatively new step in the process. I desoldered the RCA connector at the back and removed the physical switch that activates mono audio when the red RCA port is unplugged. An alternative is to cut the trace to isolate the metal clip. However, I prefer the method below since I have a desoldering iron that makes this task much easier.

Clip that enables mono audio is pulled out.

# STEP 4: Connect Sync, Audio and Ground

Wire colors

• Black wires is common ground
• Grey wire is for right audio
• White wire is for left audio
• Yellow wire is for sync
• Orange and purple wires are auxillary and can be tied away for future use.

# STEP 5: 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 1.4Copen in new window
• RGB MUX BOARD KIT 1.4Bopen in new window

Buy your RGB mux board kit

# STEP 6: 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?

Depending on your CRT, you might need to find a good place to mount the SCART port.

# Getting into the service menu

• Turn the set on and then put into standby
• Press the Display, 5, VOL + buttons in sequence
• Turn on the CRT and you should be in service mode
• Use buttons "1" and "4" on the remote control to navigate the service menu
• Use buttons "3" and "6" to adjust the selected data

# Pictures of the mod

# OSD mux mod

# Games

SNES - Metroid

SNES - Super Mario World

SNES - Yoshi's Island

NES - Adventure Island

PS1 - Boot

XBOX

# From different 20S42 set

OSD overlay

SNES - Metroid

SNES - Super Mario World

SNES - Contra

NES - Adventure Island

NES - Adventure Island closeup

PS1 - Boot

SNES Megaman X closeup

Contra 3 closeup

XBOX - UnleashX

# Patterns

Grid

# Set Pictures

# Pictures

# Photos by Suntharopen in new window

Modifying a Sony KV-20S42 to display a beautiful RGB image.

# Reference Photos

See more photos and contributions →open in new window