Toshiba 27A34
Toshiba 27A34 CRT RGB mod
This RGB mod was performed by Kaz on a 27A34. It is a fairly straightforward 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.
Specs
- Chroma: TA1310AN
Service manuals
Performing the mod
STEP 1: Remove the grounding resistors and capacitors
Remove the three 820Ω RGB resistors to ground
OSD grounding resistors R141, R142, and R143 should be removed. The inline capacitors C136, C137, and C138 should be removed and replaced with jumpers. I forgot to take a photo of the chassis for this step, but the diagram attached shows where the components are located on the chassis.
STEP 2: Replace jumpers with capacitors and diodes, then connect RGB and blanking
Remove jumpers W107, W108, and W112 from the chassis and replace them with 1N4148 diodes and 0.1uF ceramic capacitors. Picture below illustrates the direction of these components as well as where the RGB lines should be connected. Pay attention to the direction of the diodes. The blanking wire (brown) should be connected to jumper W114.
STEP 3: Connect sync, ground, and audio
Sync should be injected to the Component Luma (Y) input and audio goes to its respective audio lines. See the attached photo for the location which the wires should be connected to.
STEP 4: 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.
| Changes on the mux board | Toshiba 27A34 |
|---|---|
| CRT RGB inline resistor (on chassis) | 3.9kΩ |
| Removed resistor value (on chassis) | 820Ω |
| Add blanking diode on chassis? | No |
| Add RGB diodes on chassis? | Yes |
| RGB termination (R1, R2, R3) | 75Ω |
| RGB inline resistors (R4, R5, R6) | 750Ω |
| Audio LR (R7, R8) | shorted |
| Diode (R9) | 1N4148 |
| Blanking Ground Resistor (R10) | open |
| Blanking Resistor (R11) | shorted |
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?
Pictures
Muxed OSD over RGB
Games
