Manuales Tecnicos

CONFIDENTI
AL
TFT-LCD MONITOR
Chassis
GH19B*

Model
191T

Manual

SERVICE
TFT-LCD MONITOR

CONTENTS
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

CONFIDENTI
AL

1 Precautions

Follow thesesafety, servicing and ESD precautions to prevent damage and to protect against potential hazards such as
electrical shock.

1-1 Safety Precautions
1-1-1 W arnings
1.

For continued safety, do not attempt to modify the
circuit board.

2.

Disconnect the AC power and DC Power Jack
before servicing.

3.

(READING SHOULD
NOT BE ABOVE 0.5mA)

When the chassis is operating,semiconductor
heatsinks are potential shock hazards.

TEST ALL
EXPOSED METAL
SURFACES

1-1-2 Servicing the LCD Monitor
1.

2.

1-1-3 Fire and Shock Hazard
Before returning the monitor to the user, perform the
following safety checks:
1.

Inspect each lead dress to make certain that the
leads are not pinched or that hardware is not
lodged between the chassis and other metal parts in
themonitor.

2.

Inspect all protective devices such as nonmetallic
control knobs, insulating materials, cabinet backs,
adjustment and compartment covers or shields,
isolation resistor-capacitor networks, mechanical
insulators, etc.

3.

2-WIRE CORD

When servicing the LCD Monitor, remove the static
charge by connecting a 10k ohm resistor in series
with an insulated wire (such as atest probe)
between the chassis and the anode lead.
(Disconnect the AC line cord from the AC outlet.)
It is essential that service technicians have an
accurate voltage meter available at all times. Check
the calibration of this meter periodically.

Leakage Current Hot Check (Figure 1-1):
WARNING: Do not use an isolation transformer
during this test.
Use a leakage current tester or ametering system
that complies with American National Standards
Institute (ANSI C101.1, Leakage Current for
Appliances), and Underwriters Laboratories (UL
Publication UL1410, 59.7).

GH19B*

LEAKAGE
CURRENT
TESTER

DEVICE
UNDER
TEST

ALSO TEST WITH
PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED)
E ARTH
GROUND

Figure 1-1. Leakage Current Test Circuit
4.

With the unitcompletely reassembled, plug the AC
line cord directly into a 120V AC outlet. With the
unit’s AC switch first in the ON position and then
OFF, measure the current between a known earth
ground (metal water pipe, conduit, etc.) and all
exposed metal parts, including: metal cabinets,
screwheads and control shafts. The current
measured should not exceed 0.5 milliamp. Reverse
the power-plug prongs inthe AC outlet and repeat
the test.

1-1-4 Product Safety Notices
Some electrical and mechanical parts have special
safety-related characteristics which are often not
evident from visual inspection. The protection they give
may not be obtained by replacing them with
components rated for higher voltage, wattage, etc. Parts
that have special safety characteristics are identified by
! onschematics and parts lists. A substitute
replacement that does not have the same safety
characteristics as the recommended replacement part
might create shock, fire and / or other hazards. Product
safety is under review continuously and new
instructions are issued whenever appropriate.

1-1

CONFIDENTI
AL

1 Precautions

1-2 Servicing Precautions
WARNING:

An electrolytic capacitorinstalled 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....