Toshiba 20A42
Toshiba 20A42 CRT RGB mod
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
Schematics
Get hold of the schematics for your TV. Understand where the RGB and Fast Blanking signals go from OSD to the Jungle (Chroma) chip.
Points where the R, G, B and Blanking (brown) wires should be connected are marked on the above diagram.
Performing the mod
STEP 1: Remove the following components
Remove the three 680Ω, RGB resistors to ground
- R102 (680Ω)
- R103 (680Ω)
- R104 (680Ω)
STEP 2: Connect RGBs, Blanking and Audio
STEP 3: Build your mux circuit
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 | 13A21 | RGB Mux Board Notes |
|---|---|---|
| RGB termination | 75Ω | R1, R2, R3 |
| RGB inline resistors | 680Ω | R4, R5, R6 |
| Audio LR | 1kΩ | R7, R8 |
| Blanking inline | 1N4148 | R9 (CRT internal 4.7kΩ resistor for 2.5V) |
| Blanking ground | open | R10 (CRT internal grounding resistor is used) |
| Diode | 4.7kΩ | R11 |
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?
Pictures
