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HP S7500/MV7500/ CV7500
1 Precautions
Fol low these safety and servicing precautions to prevent damage and to protect against potential hazards
such as elect rical shock and X-rays.
1-1 Safety Precautions
1-1-1 Warnings
1. For safety purpose, do not attempt to modify
the circuit board, and always disconnect the AC
pow er before performing servicing on the
moni tor.
2. Operat ion of the monitor outside its cabinet or
with the cover removed involves the risk of
shock hazard. Repair work on the monitor
shoul d only be attempted by service personnel
who are t horoughly familiar with all necessary
safet y precautions and procedures for working
on high volt age equipment.
3. D o not lift the CRT by the neck. After
completel y discharging the high voltage anode,
handle t he CRT only when wearing shatterproof
goggles. T ry to keep the CRT away from the
body during handling.
4. Hi gh voltage should always be kept at the rated
value, no higher. Only when high voltage is
excessi ve are X-rays capable of penetrating the
shell of the CRT . Operation at high voltages
may also cause failure of the CRT or high
voltage ci rcuitry.
5. The CRT is especially construct ed to limit Xray emi ssion to 0.5mR/HR at 300 microamperes
anode c urrent. To ensure continued X-ray
protection, repl ace the CRT with only the same
or equivalent type as t he original, and adjust the
anode’s voltage to the designated maximum
rat ing, never to exceed.
1-1-2 Safety Checks
Before returning the monitor to t he user, perform
the following safet y checks:
1. Inspect to make certain that each lead dress is
not pin ched or that hardware is not lodged
between the chassis and other met al parts in
the monitor.
2. In spect all protective devices such as
nonmet allic control knobs, insulating materials,
cabinet backs, adjustment and compartment
covers or shields, isol ation resistor-capacitor
networks, mechanical i nsulators, etc.
3. AC L eakage Current Check
Always perform the AC Leakage Current
Check on the exposed metal parts, incl uding
metal cabinet s, screwheads and control shafts,
as follows:
a) Plug the AC line cord directly i nto a rated
A C outlet. Do not use an isolation
transformer during the check.
b) Use an AC volt meter with at least 5000
ohms per vol t sensitivity as follows:
Con nect a 1500 ohms, 10 watt resistor
parall eled by a 0.15uF AC capacitor in series
wit h all exposed metal cabinet parts and a
known earth ground, such as electrical
conduct or electrical ground connected to
earth ground, as shown in the Fi gure 1-1.
Me asure the AC voltage across the
combinati on of resistor and capacitor.
c) Reverse the AC plug at the AC outlet and
rep eat the steps for AC voltage
measurement s for each exposed metal part.
d) Vol tage reading must not exceed 0.3 volts
RMS , equivalent to 0.2 milliampere AC. Any
value exceeding this limit ill constitute a
p otential shock hazard and must be
corrected i mmediately.
Figure 1-1. Set Up For AC Leakage Current Check
To known
earth ground