Important Service Safety Precautions - Samsung MA267 Series Service Manual

IMPORTANT SERVICE SAFETY PRECAUTIONS
Service
w~rk
should be performed only by qualified service technicians who are thoroughly familiar with all of
the following safety checks and servicing guidelines:
WARNING
1. For continued safety,do not attempt to modify
the circuit.
2. Disconnect the AC power before servicing.
3. Semiconductor heat sinks are potential shock
hazards when the chassis is operating.
SERVICING TEE HIGH VOLTAGE SYSTEM AND
PICTURE TUBE
When servicing the high voltage system, remove the
static charge by connecting a 10kohm resistor in
series with an insulated wire(such as a test probe)
between the chassis and the anode lead. (The AC
line cord should be disconnected from the AC outlet.)
1. The picture tube in this display monitor employs
integral implosion protection.
2. Replace with a tube of the same type and
number for continued safety.
3. Do not lift the picture tube by the neck.
4. Handle the picture tube only when wearing shat-
ter proof goggles and after discharging the high
voltage anode completely.
X-RADIATION AND HIGH VOLTAGE LIMITS
1. Be sure all service personnel are aware of the
procedures and instructions covering X-radia-
tion. The only potential source of X-ray in a
current solidstate display monitor is the tube.
However,the picture tube does not emit
measurable X-ray radiation if the high voltage is
as specified in the "high voltage check" instruc-
tion.
It is only when high voltage is excessive that
X-radiation is capable of penetrating the shell of
the picture tube,including the lead in glass
material. The important precaution is to keep
3
the high voltage below the maximum level
specified.
2. It is essential that serviceman have available at
all times an accurate high voltage meter. The
calibration of this meter should be checked
periodically.
3. High voltage should always be kept at the rated
value - no higher. Operation at high voltages
may cause a failure of the picture tube or high
voltage circuitry and,also under certain condi-
tions,may produce radiation in excess of
desirable levels.
4. When the high voltage regulator is operating
properly there is no possibility of an X-radiation
problem.
Everytlme a color chassis is serviced,the bright-
ness should be tested while monitoring the high
voltage with a meter to be certain that the high
voltage does not exceed the specified value and
that it is regulating correctly.
5. Do not use a picture tube other than that
specified or make unrecommended circuit
modifications to the high voltage circuitry.
6. When troubleshooting taking test measurements
on a display monitor with excessively high volt-
age, avoid being unnecessarily close to the
display monitor. Do not operate the display
monitor longer than is necessary to locate the
cause of excessive Voltage.
BEFORE RETURNING THE DISPLAY MONITOR
Fire and Shock Hazard
Before returning the display monitor to the user,per-
form the following safety checks:
1. Inspect all 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 display monitor.