Sharp 27L-S100

# Sharp 27L-S100 CRT RGB mod

This tutorial covers the RGB mod for Sharp 27L-S100. These instructions should also work for other SN-91 chassis based Shartp CRTs.

The Sharp 27L-S100 is a 27" standard-definition (SD) curved CRT television from the late 90s/early 2000s.

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

# Contributors

Thank you to everyone who contributed to this guide:

• Ivan LaCoursiereopen in new window — contributor, RGB mod and pictures

# CRT safety

READ THIS BEFORE CONTINUING

# Plan of attack

READ THIS TO PREPARE

# Manuals and Datasheets

• Sharp 27L-S100 Service Manualopen in new window

# Specs

• Year: 1999
• Format: NTSC
• Chassis: SN-91
• Tube: A68ADT25X03
• Jungle Chip: Sharp IX3253CE
• OSD Chip: Sharp IX3256CE
• Screen Size: 27"
• Inputs: Composite, RF

# RGB mux diagram

Prepare the mux diagram. If you are building your own circuit, this diagram should help.

# Schematics

IX3253CE Chroma Chip

# RGB external resistor value and Blanking voltage

Love it when we can put theories to use! Formula from our theory page!

For this particular mod we are going to use diodes inline to prevent signal reflection.

RGB external resistor value = 0.7 x (6800 + 75) - (75 x (5 - 0.7)) / (5 - 0.7 - 0.7) = (4812 - 322) / 3.6 = 1247 ohm

~ 1.2 Kohm resistors should do the job.

For this particular set, we are also going to use 220Ω termination resistance instead of the standard 75Ω resistance to achieve proper contrast levels.

We can find that chroma chip blanks at a voltage slightly higher than 1.5V using the existing resistance values used for voltage dividing. 6.8kΩ and 3.3kΩ. Since we are going to add a diode inline, we need to compensate for that voltage drop. We have to replace the 3.3kΩ resistor with a 4.2k achieve the same voltage levels. At 1.6V, OSD gain will be correct and allow the external RGB input on pin 15-17.

# Performing the mod

Now that you roughly know what needs to be done, prepare for the mod. Place the board 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.

• R803 (2.2 kΩ)
• R804 (2.2 kΩ)
• R805 (2.2 kΩ)

# STEP 2: Connect RGBs, Blanking and Audio

Coax cable was used for this particular mod. This is optional and only needed if you care every bit about the interference. Using the standard unshielded ribbon cable should be sufficient, however that might not always work well.

Make sure to install inline diodes on R, G, B and another diode on blanking right after the 6.8kΩ resistor to reduce signal noise.

Below picture was taken before and after adding the diodes.

# STEP 3: 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.

Compatible mux boards:

• RGB MUX BOARD KIT 1.4Copen in new window
• RGB MUX BOARD KIT 1.4Bopen in new window

Buy your RGB mux board kit

# STEP 4: Attach the female SCART connector to TV

Creating a SCART cutout and mounting it is an art. There is a dedicated section for it.

After attaching the RGB mux board

# Remote Control for this TV

# Getting into service menu

While pressing the Vol-up and Ch-up buttons at the sametime, plug the AC cord into a wall socket.

# Pictures

# Reference Photos

See more photos and contributions →open in new window