WARNINGS and CAUTIONS
IMPORTANT SAFETY NOTICE: Under no cir-
cumstances should the original design be modified or
altered without permission from Zenith Electronics
Corporation. All components should be replaced only
with types identical to those
in
the original circuit, and
their physical location, wiring, and lead dress must
conform to the original layout upon completion of re-
pairs.
In
some instances, redundant circuitry
is
used for addi-
tional circuit protection and X-radiation protection.
Special circuits are also used to prevent shock and
fire hazard. These special
circuit
components
con-
tain
an X
in
their
reference
designator
(CX501
is
an example). They are
to
be replaced
with
identical
components
only.
WARNING: No work should be attempted on any part
of the chassis by anyone not familiar with Zenith ser-
vice procedures and precautions. Otherwise, personal
injury may result.
WARNING: External isolation transformers should al-
ways be used when test equipment is connected to
the monitor. This is to reduce a lethal shock hazard,
monitor damage, and test eqUipment damage that
could result from the monitor and/or test equipment
chassis being connected to different sides of the AC
line.
WARNING:
Do
not operate a monitor with excessive
high voltage because the monitor will produce X-rays
from the CRT when the high voltage is excessive. Al-
ways verify that the high voltage is at the normal level
when servicing the unit.
WARNING: Discharge the high voltage at the anode
lead of the CRT before attempting service on the high
voltage supply or associated circuits. Refer to the ser-
vicing section ofthis manual for detailed instructions.
WARNING: The CRT and the attached CRT board
loses support once the back cover is removed. Use
extra care when repositioning the monitor. Turn the
power off and disconnect the power cord before at-
tempting to reposition the monitor.
WARNING: Handle the cathode-ray tube carefully
when
you
hold, remove, or install it; otherwise implo-
sion and/or personal injury may result.
WARNING: To prevent electrical shock after reassem-
bly, perform
an
AC
leakage test on all exposed metal
parts of the monitor.
Do
not use a line isolation trans-
former to perform this test.
Any leakage voltage measurement that exceeds 0.75
volts rms (0.5 milliamperes AC) constitutes a potential
shock hazard and must be corrected. These voltage
and current values are based upon the following test
meter circuit (Figure
1)
and the following test instruc-
tions.
1.
2.
3.
4.
Connect the test circuit as shown
in
Figure 1.
With monitor power turned on, measure the
leakage voltage between earth ground and an
exposed monitormetal part.
Repeat the measurement with the meter leads
reversed.
Repeat steps 2 and 3 until all exposed monitor
metal parts are verified to have satisfactory AC
leakage levels.
A.C.
VOLTMETER
(5K
OHM/VOLT
MINIMUM)
I~I
22-4384
.15uF
AC
TYPE
...JL
rh
1\
PLACE
THI
ROUND
63-10401-76
ON
EACH
PIPE.
TO
GOOD
EARTH
G
SUCH
AS
WATER
CONDUIT.
ETC.
S
PROBE
EXPOSED
PART.
METALLIC
1500n
10
WATT
Figure1
AC Leakage Voltmeter
Circuit
iii
