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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.
5. When re-
assembling the monitor after service, take care to ensure that the degauss coil is not trapped and does not have its
insulation damaged by screws, the metal card tray, or shielding edges.
Page
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59
4V SERIES MANUAL
05.06.2002
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C551.htm