4
2. PRECAUTIONS AND NOTICES
2-1 SAFETY
PRECAUTIONS
1. Observe all caution and safety related notes located inside the display cabinet.
2. Operation of the display with the cover removed, may cause a serious shock hazard from the display
power supply. Work on the display should not be attempted by anyone who is not thoroughly familiar
with precautions necessary when working on high voltage equipment.
3. Do not install, remove or handle the picture tube in any manner unless shatter-proof goggles are worn.
People who are not so equipped should be kept away while handling picture tube. Keep picture tube away
from the body while handling.
4. The picture tube is constructed to limit X-RAY radiation to 0.5 MR/HR. For continued protection, use the
designated replacement tube only, and adjust the voltages so that the designated maximum rating at the
anode will not be exceeded.
5. Before returning a serviced display to the customer, a thorough safety test must be performed to verify
that the display is safe to operate without danger or shock. Always perform an AC leakage current check
on the exposed metallic parts of the cabinet, such as screw heads.
Test method for current leakage is described as follow.
(a) Plug the AC line cord directly into rated AC outlet (do not use a line isolation transformer during
this check).
(b) Use an AC voltmeter having 5000 ohms per volt or with more sensitivity in the following manner:
Connect a 1500 ohms 10 Watt resistor, paralleled by a 0.15UF, AC type capacitor between a known
good earth ground (water pipe, conduit, etc.) and the exposed metallic parts simultaneously.
Measure the AC voltage across the combination of 1500 ohms resistor and 0.15UF capacitor.
(c) Reverse the AC plug at the AC outlet and repeat AC voltage measurements for each exposed
metallic part.
(d) Voltage measured must not exceed 0.5 volts RMS. This corresponds to 0.35 milliamp AC. Any
value exceeding this limit constitutes a potential shock hazard and must be corrected immediately.
2-2
PRODUCT SAFETY NOTICE
Many electrical and mechanical parts in this chassis have special safety visual inspections and the protection
afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage,
wattage, etc. Before replacing any of these components read the parts list in this manual carefully. The use of
substitute replacement parts which do not have the same safety characteristics as specified in the parts list may
create shock, fire, X-RAY radiation or other hazards.
2-3 SERVICE
NOTES
1. When replacing parts or circuit boards, clamp the lead wires around terminals before soldering.
2. When replacing a high wattage resistor (more than 1/2W of metal oxide film resistor) in circuit board,
keep the resistor about 10mm (1/2 in) away from circuit board.
3. Keep wires away from high voltage or high temperature components.
4. Keep wires in their original position so as to reduce interference.
2-4
HIGH VOLTAGE WARNING
Operation of monitor outside of cabinet or with back removed may cause a serious shock hazard. Work on this
model should only be performed by those who are thoroughly familiar with precautions necessary when
working on high voltage equipment.
Exercise care when servicing this chassis with power applied. Many B plus and high voltage terminals are
exposed which, if carelessly contacted, can cause serious shock or result in damage to the chassis. Maintain
interconnecting ground lead connections between chassis and picture tube dag when operating chassis.
Certain HV failures can increase X-ray radiation. Monitor should not be operated with HV levels exceeding the
specified rating for the chassis type. The maximum operating HV specified for the chassis used in this monitor
is
24.0KV
±
1KV
with a line voltage of 120/240 VAC. Higher voltage may also increase possibility of failure in HV supply.
It is important to maintain specified values of all components in the horizontal and high voltage circuits and
anywhere else in the monitor that could cause a rise in high voltage or operating supply voltages. No changes
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