# Sony BA-5 Chassis CRT RGB mod

Below mod was performed on KV-20FV12.

This tutorial should also cover the RGB mod for the below models with the BA-5 chassis. However, there might be slight differences.

  • KV-20FS12
  • KV-20FV12
  • KV-21FE12
  • KV-21FM12
  • KV-27FS13
  • KV-27FS17
  • KV-27FV17
  • KV-29FV17
  • KV-32FS13
  • KV-32FS17
  • KV-34FS17

# CRT safety


You can die doing this! So read carefully! CRT TV is not a toy. Do not open a CRT TV. If you don't have any prior knowledge about handling high voltage devices, this guide is not for you. CRT TV contains high enough voltage (20,000+ V) and current to be deadly, even when it is turned off.


# Plan of attack


# 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.


# Service manuals

# Specs

# Sony KV-20FV12

  • Manufactured: October 2001, Mexico
  • NTSC, 60 Hz
  • Chassis: BA-5
  • Tube:
  • Jungle Chip: CXA2131CS
  • OSD Chip: M37273MF

# Schematics

Sony BA-5 chassis schematics

# Mux diagram

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

Sony BA-5 chassis RGB mod mux diagram

# Calculating the RGB external resistor value

Formula from our theory page!


RGB external resistor value = 0.7 x (6800 + 75) - (75 x 5) / (5 - 0.7) = (4812 - 375) / 4.3 = 1030 ohm

~ 1 Kohm resistors should do the job.

# 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.

# STEP 1: Remove the following components

BA5 chassis - MB Board

Remove the following components. RGB resistors to the ground. Measure twice and mark before you remove.

  • R1084 (680Ω)
  • R1085 (680Ω)
  • R1086 (680Ω)

# STEP 2: Connect RGBs, Blanking and Audio

See picture above to see where blanking should be connected.

Let's remove the jumpers JW1335, JW1336, JW1337 and replace with 3 1N1418 diodes. Pay attention to the direction of the diodes. There is a black bar indicating which way the current flows. This helps reduce feedback noise and voltage going back into the OSD.

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

Twist the orange and yellow wires. Sync wire (yellow) should be connected directly to the s-video Y pin. Ground wire (orange) should be connected to the ground. Audio wiring can go below the board. Connect audio left (white) and audio right (grey) as seen in the pics below.

Ground both common ground (black) and audio ground (purple) wires.


# STEP 3: 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

TV Model KV-20FV12
Audio LR (R7, R8) Shorted
RGB termination (R1, R2, R3) 75Ω
RGB inline resistors (R4, R5, R6) 1kΩ
Diode (R9) 1N4148
Blanking Resistor (R11) 2.2kΩ

You have to be strategic about the board placement. Sony KV-20FV12 has tight spacing with flyback and the audio board on the way.

Buy your RGB mux board

# STEP 4: 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?

# 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

# Mux and OSD

Volume img

Menu img

# Games

NES - Adventure Island img

SEGA Genesis - Sonic img

SNES - Contra img

SNES - Alien img

XBOX - UnleashX img

PS1 - Boot img

# Patterns

SMPTE - Colors img

Grid img

Monoscope img

# Inside of the CRT

Gut of the CRT (comes off completely). Main chassis, MB board, Neck board img

Tube and speakers img

Neck board img