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 SN91 chassis based Shartp CRTs.

# CRT safety

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

# Service manuals

• Sharp 27L-S100 Service Manual

# Specs

# Sharp 27L-S100

• Manufactured: February 1999, New Jersey
• NTSC, 60 Hz
• Chassis: SN91
• Tube: A68ADT25X03
• Jungle Chip: IX3253CE
• OSD Chip: IX3256CE

# Schematics

IX3253CE Chroma Chip

# Mux diagram

If you are building your own circuit, this diagram should help

# 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

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.

Buy your RGB mux board

Buy your RGB mux board

# 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

# PS2 games

Castlevania

Naughty Dog

Crash Bandicoot

# Patterns

SMPTE pattern

# CRT

Bonded yoke

Neck board

Finished CRT