JVC AV-27230

Sunthar's Super Store Eli KrauseAbout 6 min

JVC AV-27230 CRT RGB mod

The JVC AV-27230 is a 27" CRT television from the early 2000s, sharing the same high-quality tube and picture performance as the popular JVC D-Series, but with a smaller footprint. It features component, S-Video, and composite inputs, 600 lines of horizontal resolution, a 3-line digital comb filter, and is RGB modifiable.

The tube on this model is exceptional with impressive geometry, and unlike the highly coveted JVC D-Series (e.g. AV-27D201), there were no distracting funhouse scrolling problems observed. Therefore, if you own a JVC curved set that can be RGB modified (some can't be modified), I strongly endorse trying out this modification.

JVC AV-27230 RGB image

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

In this tutorial, we will be discussing the RGB modification process for the JVC AV-27230 CRT.

Contributors

Thank you to everyone who contributed to this guide:

Sunthar's Super Storeopen in new window — photos and documentation
Eli Krauseopen in new window — contributor, CRT specs

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.

READ THIS BEFORE CONTINUING

Plan of attack

READ THIS TO PREPARE

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.

READ THE RGB MODDING THEORY

Manuals and Datasheets

Specs

Year: 2001
Format: NTSC
Chassis: FD
Tube: Thomson A68ADT25X01
Jungle Chip: Toshiba TB1253AN
OSD Chip: M37272MA-314SP
Screen Size: 20"
Inputs: Composite, S-Video, RF, Component YPbPr

Schematics

PCB diagram

RGB mux diagram

JVC AV-27230 RGB MUX diagram

Performing the mod

Now that you roughly know what needs to be done, prepare for the mod. Place the main chassis on a comfortable place. Make sure you are not putting pressure on the flyback or other components.

STEP 1: Remove the following components

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

R738 (1.5 kΩ)
R740 (1.5 kΩ)
R742 (1.5 kΩ)

Note: It was strange that the chassis did not include a ground resistor for blanking. This ground resistor is shown in the schematics however. To address this issue, a 4.7 kΩ (R10) ground resistor was added to the mux board.

STEP 2: Install diodes to reduce noise

Add 1N4148 diodes by replacing jumpers W177(R), W178(G), W026(B) and W214(Blanking)

W177
W178
W026
W214

Pay attention to the direction of the diodes. Also, install the diodes on the component side of the chassis, as seen in the picture below.

STEP 3: Connect RGBs, Blanking and Audio

The picture presented below depicts the appropriate placement for soldering the R, G, B, and blanking wires onto the solder side of the chassis. It is crucial to solder them on the correct side of the diode installation location, as illustrated in the image.

The sync was linked to the component luma pin, while the audio was connected to the corresponding left and right audio inputs. It's important to remember that in order for the stereo sound to function properly, a dummy RCA must be inserted into the right channel's red audio RCA port.

The ground wires consist of the purple and black wires, with an additional redundant ground wire in orange. The latter was deliberately cut off and insulated, taking care to avoid any short circuits on the main chassis.

STEP 4: 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.

Component	Value
RGB/OSD inline resistor (chassis)	4.7kΩ
Removed RGB/OSD resistor (chassis)	1.5kΩ
RGB inline diode method (chassis)	Yes
RGB termination (R1, R2, R3)	220Ω
RGB inline (R4, R5, R6)	1kΩ
Audio LR (R7, R8)	1kΩ
Blanking Ground Resistor (R10)	4.7kΩ
Blanking Resistor (R11)	1kΩ

Buy your RGB mux board kit

This mod uses the RGB mini mux board (Rev C)

Buy your RGB mux board

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?

Press the SLEEP TIMER key and set the SLEEP TIMER for 0 MIN
While the SLEEP TIMER is displaying on the CRT, do the below
Immediately press the DISPLAY key and the VIDEO STATUS key of the remote control unit at the same time.
Then enter the SERVICE MENU screen shown in figure.