FEATURES Service Warning
1. Flat screen CRT with anti-glare, dynamic focus circuit, With minimum Brightness and Contrast the operating
dark glass, and INVAR shadow mask give the high voltage in this display is lower than 30 kV.
sharpest focus and highest contrast. If any component having influence on the high voltage is
replaced, confirm that the high voltage with minimum
2. Automatic scanning and automatic adjustment to
conform to a wide range of scanning frequencies and Brightness and Contrast is lower than 30 kV.
To measure high voltage use a high impedance
user requirements. high-voltage meter. (SENSITIVE RESEARCH Model:
3. Signal input allows D-Sub Mini 15-pin cable. ESH or Equivalent)
4. Power Save Mode automatically puts the monitor into Connect (-) to chassis earth and (+) to the CDT anode
a standby mode (power consumption less than 15W) button. (See the following connection diagram Fig. 1.)
when the H.sync. signal is not detected, and a power - NOTE: Turn power switch off without fail before making
off mode (less than 5W) when the V.sync. signal is not the connection to the Anode button
detected. Normal mode is restored immediately when
the H. sync. signal and the V.sync. signal are detected.
CDT ANODE
This feature prolongs monitor life and reduces energy
consumption by up to about 75 %.
(+)
SAFETY PRECAUTIONS
(-)
NOTICE: Comply with all cautions and safety related
notes located on or inside the cabinet and on the chassis
or picture tube. HIGH IMPEDANCE
The following precautions must be observed. H.V. METER
SENSITIVE RESEARCH
1. Do not install, remove, or handle the picture tube in Model: ESH or equivalent. CHASSIS GROUND
any manner unless shatterproof goggles are worn. FIG. 1
People not so equipped should be kept away while
picture tubes are handled.
2. When replacing a chassis in the monitor, all the X-radiation
protective devices must be put back in place, such as, TUBE: The source of X-radiation in this monitor is the
barriers, non-metallic knobs, adjustment and compartment picture tube. The tube utilized in this chassis is specially
constructed to limit X-radiation emissions.
shields, and isolation resistor-capacitor, etc.
3. When service is required, observe the original lead For continued X-radiation protection, the replacement
tube must be the same type as the original, manufacturer
dress. Extra precaution should be taken to assure
correct lead dress in the high voltage circuitry area. approved type.
When troubleshooting and making test measurements in
4 Always use the manufacturer?s replacement components. a monitor with a problem of excessive high voltage, avoid
Especially critical components as indicated on the being unnecessarily close to the picture tube and the high
circuit diagram should not be replaced by other voltage components.
manufacturer?s one. Furthermore where a short circuit Do not operate the chassis longer than is necessary to
has occurred, replace those components that locate the cause of excessive voltage.
indicate evidence of overheating.
5. Before returning a serviced monitor to the customer,
the service personnel must thoroughly test unit to be CHECK OF HIGH VOLTAGE HOLD DOWN
certain that it is completely safe to operate without CIRCUIT
danger of electrical shock, and be sure that no Checking of the high Voltage hold down circuit operation.
protective device built into the monitor by the 1. Turn the switch of the unit ON, and set the Brightness
manufacturer has become defective, or inadvertently
and Contrast controls to max.
defeated during servicing.
Therefore, the following checks should be performed 2. Turn the switch of the unit OFF.
for continued protection of the customer and service 3. Connect a DC Voltmeter and an adjustment jig as
technician. shown in Fig. 2.
6. In the case of the microprocessor unit, shop 4. Set the adjustment VR to fully counterclockwise.
adjustment is necessary after exchange of the 5. Turn the switch of the unit ON and gradually rotate the
microprocessor unit.
adjustment VR clockwise.
6. Check that a reading of DC voltage-meter is less-than
High Voltage 0.60.1 V when picture disappears.
This monitor is provided with a high voltage hold down 7. Turn the switch of the unit OFF immediately after
circuit for clearly indicating that voltage has increased in
excess of a predetermined value. checking that the picture disappears.
8. Remove the adjusting jig and the DC voltmeter.
Comply with notes described in this Service Manual
regarding this hold down circuit when servicing, so that NOTE: Reading of 0.6 V is approximately equivalent to
this hold down circuit may function correctly. 30 kV of CDT Anode High Voltage.
2 |
ACEC
HITACHI
