JVC AV-27120

JVC AV-27120 CRT RGB mod

In this tutorial, we will be discussing the RGB modification process for the JVC AV-27120 CRT. RGB mod for JVC AV-27220 is also very similar. This particular model boasts an exceptional tube with impressive geometry. 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.

The JVC AV-27120 is a 27" consumer CRT tv released around early 2000s, featuring a curved "bubble" tube similar to the JVC D-Series. It features RF, Composite, and S-Video inputs and is a great candidate for RGB modding.

JVC AV-27120 RGB image

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

Contributors

Thank you to everyone who contributed to this guide:

Martin Seibertopen in new window — author, RGB mod and pictures

Reddit Threadopen in new window

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

Manuals and Datasheets

Specs

Year: 2001
Format: NTSC
Chassis: FV3
Tube: JVC A68ADT25X01
Jungle Chip: Toshiba TA1242N
OSD Chip: Mitsubishi M37272MA-314SP
Screen Size: 20"
Inputs: Composite, S-Video, RF, Component YPbPr

RGB mux diagram

JVC AV-27120 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)

STEP 2: Install diodes to reduce noise

Diodes were not installed on chassis for this mod. However, it is recommended to reduce noise. See JVC-AV27230.

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. Please remember, the below R, G, B, blanking solder locations for wiring would be different if you were to install diodes.

The sync was connected to the composite input that was already 75Ω terminated, 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.

Black wire is the common ground for both audio and video. Purple and orange wires are for auxillary purposes and can be grounded (suppose you want to add a switch based mod or you can also use them for S-Video mod).

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)

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.

Sonic