CONFIDENTIAL
1 Precautions
1-1 Safety Precautions
WARNINGS2. Inspect all protective devices such as nonmetallic
1. For continued safety, do not attempt to modify thecontrol knobs, insulating materials, cabinet backs,
circuit board.adjustment and compartment covers or shields,
isolation resistor-capacitor networks, mechanical
2. Disconnect the AC power before servicing.
insulators, etc.
3. When the chassis is operating, semiconductor
3. Leakage Current Hot Check (Figure 1-1):
heatsinks are potential shock hazards.
WARNING: Do not use an isolation transformer during
1-1-1 Servicing the High Voltage and CRT :this test.
WARNING: A high voltage VR replaced in theUse a leakage current tester or a metering system
wrong direction may cause excessive that complies with American National Standards
X-ray emissions.Institute (ANSI C101.1, Leakage Current for
Appliances), and Underwriters Laboratories (UL
1. When servicing the high voltage system, remove
Publication UL1410, 59.7).
the static charge by connecting a 10 kohm resistor
4. With the unit completely reassembled, plug the AC
in series with an insulated wire (such as a test
line cord directly into a 120V AC outlet. With the
probe) between the chassis and the anode lead.
unitOs AC switch first in the ON position and then
2. When troubleshooting a monitor with excess HV,
OFF, measure the current between a known earth
avoid being unnecessarily close to the monitor. Do
ground (metal water pipe, conduit, etc.) and all
not operate the monitor for longer than is necessary
exposed metal parts, including: metal cabinets,
to locate the cause of excessive voltage.
screwheads and control shafts. The current
3. High voltage should always be kept at the ratedmeasured should not exceed 0.5 milliamp. Reverse
value (not higher). Only when high voltage isthe power-plug prongs in the AC outlet and repeat
excessive are X-rays capable of penetrating the shellthe test.
of the CRT, including the lead in glass material.
(READING SHOULD
Operation at high voltages may also cause failure ofNOT BE ABOVE 0.5mA)
the CRT or high voltage circuitry.
4. When the HV regulator is operating properly, thereLEAKAGE
DEVICECURRENT
is no possibility of an X-ray problem. Make sure theUNDERTESTER
TEST
HV does not exceed its specified value and that it is
TEST ALL
regulating correctly.EXPOSED METALSURFACES
5. The CRT is especially designed to prohibit
2-WIRE CORD
X-ray emissions. To ensure continued X-ray
protection, replace the CRT only with one that is
the same or equivalent type as the original.ALSO TEST WITH
PLUG REVERSED
6. Handle the CRT only when wearing shatterproof(USING AC ADAPTER
PLUG AS REQUIRED)EARTH
goggles and after completely discharging the highGROUND
voltage anode.
Figure 1-1. Leakage Current Test Circuit
7. Do not lift the CRT by the neck.
1-1-3 Product Safety Notices
1-1-2 Fire and Shock Hazard
Some electrical and mechanical parts have special
Before returning the monitor to the user, perform the
safety-related characteristics which are often not
following safety checks:
evident from visual inspection. The protection they give
1. Inspect each lead dress to make certain that the
may not be obtained by replacing them with
leads are not pinched or that hardware is not
components rated for higher voltage, wattage, etc. Parts
lodged between the chassis and other metal parts in
that have special safety characteristics are identified by
the monitor.
!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.
Components identified by on schematics and parts
lists must be sealed by a soldering iron after
replacement and adjustment.
AN17K*/AN17L*1-1 |
ACEC
