Sony KV (BA-4D) 20S90 RGB
Sony KV-20S90 (BA-4D) chassis CRT RGB mod
If you're looking to get the most out of your Sony Trinitron, you may want to consider modding it for RGB output. This guide will show you how to do just that.
This is a fairly straightforward mod to perform. For CRTs that are larger than 20", it is recommended you use shielded RGB cables internally.
Below mod was performed on a Sony KV-20S90, by a reddit user /u/atomized69.
Also, checkout this latest KV-20S42 RGB mod tutorial as well.
CRT safety
Caution
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-20S90
- Manufactured: October 2001, Mexico
- NTSC, 60 Hz - 95W
- Chassis: BA-4D
- Tube: A51LDG51X
- Jungle Chip: CXA2133BS
- OSD Chip: M37273MF-255SP
Schematics
Mux diagram
If you are building your own circuit, this diagram should help. The diagram is for KV-20S42, and it will also work for KV-20S90 chassis. There are some slight differences in KV-27S42 and KV-20S42 chassis. Resistors to remove are the same, but numbering and placement on the chiassis are slightly different.
Calculating the RGB external resistor value
Formula from our theory page!
Calcualted 910Ω for 0.7Vp-p. With didoe inline for RGB, you have to use 1kΩ
Performing the mod
STEP 1 to STEP 4: Removing resistors and injecting RGBs and blanking
Follow the KV-20S42 RGB mod guide.
STEP 5: 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.
| TV Model | KV-20S40 | KV-20S90 | KV-20S42 | KV-27S42 |
|---|---|---|---|---|
| CRT inline resistors | 5.6kΩ | 5.6kΩ | 5.6kΩ | 5.6kΩ |
| Add diodes to RGB inline? | Yes | Yes | Yes | Yes |
| Add diodes to blanking on chassis? | No | No | No | No |
| RGB termination (R1, R2, R3) | 75Ω | 75Ω | 75Ω | 75Ω |
| RGB inline resistors (R4, R5, R6) | 1kΩ | 1kΩ | 1kΩ | 1kΩ |
| Audio LR (R7, R8) | 1kΩ | 1kΩ | 1kΩ | 1kΩ |
| Diode (R9) | 1N4148 | 1N4148 | 1N4148 | 1N4148 |
| Open (R10 | -- | -- | -- | -- |
| Blanking Resistor (R11) | 1kΩ | 1kΩ | 1kΩ | 1kΩ |
| Add diodes to RGB lines | Yes | Yes | Yes | Yes |
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.
Sony KV-20S90 
Reducing interference
Sometimes you might notice micro interference in the video signals. This is expected. To reduce it, try the following.
- Use diodes in-line for RGB signal
- Make sure your blanking wire is connected after the diode that feeds into the chroma chip (see diagram)
- Try routing most of the cabling below the PCB
- Keep the ribbon cable short
- I really didn't find any difference in interference in using shielded vs non-shileded cables. Therefore, this is optional.
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
Games
Super Mario Kart 
Demon's Crest 
Zombies Ate My Neighbors 
Closeup 
Patterns
Grid - KV-20S90 