Samsung SyncMaster 940Fn, Service Manual

Page: 61 / 66

1 Precautions
1-1
1-1-1 Warnings
1. For continued safety, do not attempt to modify the circuit
board.
2. Disconnect the AC power and DC power jack before
servicing.
1-1-2 Servicing the LCD Monitor
1. When servicing the LCD Monitor, Disconnect the AC
line cord from the AC outlet.
2. It is essential that service technicians have an accurate
voltage meter available at all times. Check the
calibration of this meter periodically.
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 the monitor.
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. Leakage Current Hot Check (Figure 1-1):
WARNING : Do not use an isolation
transformer during this test.
Use a leakage current tester or a metering system that
complies with American National Standards Institute
(
ANSI C101.1, Leakage Current for Appliances ), and
Underwriters Laboratories ( UL Publication UL1410,
59.7 ).
Figure 1-1. Leakage Current Test Circuit
4. With the unit completely 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 in the 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 on schematics 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 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