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Chassis Model
GH19B* 191T

1. Precautions

2. Product Specifications

3. Disassembly & Reassembly

4. Troubleshooting

5. Exploded View & Parts List

6. Electrical Parts List

7. Block Diagram

8. Wiring Diagram

9. Schematic Diagrams

10. Panel Description
1 Precautions
Follow these safety, servicing and ESD precautions to prevent damage and to protect against potential hazards such as
electrical shock.

1-1 Safety Precautions

1-1-1 Warnings
1. For continued safety, do not attempt to modify the (READING SHOULD
circuit board. NOT BE ABOVE 0.5mA)

2. Disconnect the AC power and DC Power Jack
before servicing. DEVICE
3. When the chassis is operating, semiconductor TEST
heatsinks are potential shock hazards. EXPOSED METAL

1-1-2 Servicing the LCD Monitor 2-WIRE CORD

1. When servicing the LCD Monitor, remove the static
charge by connecting a 10k ohm resistor in series ALSO TEST WITH
with an insulated wire (such as a test probe) (USING AC ADAPTER
between the chassis and the anode lead. EARTH

(Disconnect the AC line cord from the AC outlet.)
2. It is essential that service technicians have an Figure 1-1. Leakage Current Test Circuit
accurate voltage meter available at all times. Check
the calibration of this meter periodically. 4. With the unit completely reassembled, plug the AC
line cord directly into a 120V AC outlet. With the
1-1-3 Fire and Shock Hazard unit's AC switch first in the ON position and then
Before returning the monitor to the user, perform the OFF, measure the current between a known earth
following safety checks: ground (metal water pipe, conduit, etc.) and all
exposed metal parts, including: metal cabinets,
1. Inspect each lead dress to make certain that the
screwheads and control shafts. The current
leads are not pinched or that hardware is not
measured should not exceed 0.5 milliamp. Reverse
lodged between the chassis and other metal parts in
the power-plug prongs in the AC outlet and repeat
the monitor.
the test.
2. Inspect all protective devices such as nonmetallic
control knobs, insulating materials, cabinet backs,
adjustment and compartment covers or shields, 1-1-4 Product Safety Notices
isolation resistor-capacitor networks, mechanical
Some electrical and mechanical parts have special
insulators, etc.
safety-related characteristics which are often not
3. Leakage Current Hot Check (Figure 1-1): evident from visual inspection. The protection they give
WARNING: Do not use an isolation transformer may not be obtained by replacing them with
during this test. components rated for higher voltage, wattage, etc. Parts
Use a leakage current tester or a metering system that have special safety characteristics are identified by
that complies with American National Standards ! on schematics and parts lists. A substitute
Institute (ANSI C101.1, Leakage Current for replacement that does not have the same safety
characteristics as the recommended replacement part
Appliances), and Underwriters Laboratories (UL
might create shock, fire and / or other hazards. Product
Publication UL1410, 59.7).
safety is under review continuously and new
instructions are issued whenever appropriate.

GH19B* 1-1
1 Precautions
1-2 Servicing Precautions
WARNING: An electrolytic capacitor installed with the wrong polarity might explode.
Caution: Before servicing units covered by this service manual, read and follow the Safety Precautions
section of this manual.
Note: If unforeseen circumstances create conflict between the following servicing precautions and any of the
safety precautions, always follow the safety precautions.

1-2-1 General Servicing Precautions
1. Always unplug the unit's AC power cord from the 4. Check the insulation between the blades of the AC
AC power source and disconnect the DC Power plug and accessible conductive parts (examples:
Jack before attempting to: metal panels, input terminals and earphone jacks).
(a) remove or reinstall any component or assembly, 5. Insulation Checking Procedure: Disconnect the
(b) disconnect PCB plugs or connectors, (c) connect power cord from the AC source and turn the power
a test component in parallel with an electrolytic switch ON. Connect an insulation resistance meter
capacitor. (500 V) to the blades of the AC plug.
2. Some components are raised above the printed The insulation resistance between each blade of the
circuit board for safety. An insulation tube or tape AC plug and accessible conductive parts (see
is sometimes used. The internal wiring is above) should be greater than 1 megohm.
sometimes clamped to prevent contact with
6. Always connect a test instrument's ground lead to
thermally hot components. Reinstall all such
the instrument chassis ground before connecting
elements to their original position.
the positive lead; always remove the instrument's
3. After servicing, always check that the screws, ground lead last.
components and wiring have been correctly
reinstalled. Make sure that the area around the
serviced part has not been damaged.

1-3 Electrostatically Sensitive Devices (ESD) Precautions
Some semiconductor (solid state) devices can be easily damaged by static electricity. Such components are commonly
called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated circuits and some field-
effect transistors. The following techniques will reduce the incidence of component damage caused by static electricity.

1. Immediately before handling any semiconductor 6. Do not remove a replacement ESD from its
components or assemblies, drain the electrostatic protective package until you are ready to install it.
charge from your body by touching a known earth Most replacement ESDs are packaged with leads
ground. Alternatively, wear a discharging wrist- that are electrically shorted together by conductive
strap device. To avoid a shock hazard, be sure to foam, aluminum foil or other conductive materials.
remove the wrist strap before applying power to 7. Immediately before removing the protective
the monitor. material from the leads of a replacement ESD,
2. After removing an ESD-equipped assembly, place it touch the protective material to the chassis or
on a conductive surface such as aluminum foil to circuit assembly into which the device will be
prevent accumulation of an electrostatic charge. installed.
3. Do not use freon-propelled chemicals. These can Caution: Be sure no power is applied to the
generate electrical charges sufficient to damage chassis or circuit and observe all
ESDs. other safety precautions.
4. Use only a grounded-tip soldering iron to solder or
desolder ESDs. 8. Minimize body motions when handling
unpackaged replacement ESDs. Motions such as
5. Use only an anti-static solder removal device. Some brushing clothes together, or lifting your foot from
solder removal devices not classified as "anti-static" a carpeted floor can generate enough static
can generate electrical charges sufficient to damage electricity to damage an ESD.

1-2 GH19B*
2 Product Specifications
2-1 Specifications

Item Description

LCD Panel TFT-LCD panel, RGB vertical stripe, normally black transmissive,
0.298 mm pixel pitch

Scanning Frequency Horizontal : 30 kHz ~ 81 kHz (Automatic)
Vertical : 56 Hz ~ 85 Hz

Display Colors 16,7 Million colors

Maximum Resolution Horizontal : 1280 Pixels @ 81 kHz
Vertical : 1024 Pixels @ 76 Hz

Input Video Signal Analog : 0.7 Vp-p