Hitachi 46F500A, Руководство по обслуживанию

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3
DP33KA/B
IMPORTANT SAFETY INSTRUCTION
1. Before returning an instrument to the customer, always
make a safety check of the entire instrument, including
but not limited to the following items.
a. Be sure that no built-in protective devices are
defective and/or have been deleted during servicing.
(1) Protective shields are provided on this chassis to
protect both the technician and the customer.
Correctly replace all missing protective shields,
including any removed for servicing convenience. (2)
When reinstalling the chassis and/or other assembly
in the cabinet, be sure to put back in place all
protective devices, including but not limited to,
nonmetallic control knobs, insulating fishpaper,
adjustment and compartment covers/shields, and
isolation resistor/capacitor networks. Do not operate
this instrument or permit it to be operated without
all protective devices correctly installed and
functioning. Servicers who defeat safety features
or fail to perform safety checks may be liable for
any resulting damage.
b. Be sure that there are no cabinet openings through
which an adult or child might be able to insert their
fingers and contact a hazardous voltage. Such
openings include, but are not limited to (1) spacing
between the picture tube and cabinet mask, (2)
excessively wide cabinet ventilation slots, and (3) an
improperly fitted and/or incorrectly secured cabinet
back cover.
c. Antenna Cold Check – With the instrument AC plug
removed from any AC source, connect an electrical
jumper across the two AC plug prongs. Place the
instrument AC switch in the on position. Connect one
lead of an ohmmeter to the AC plug prongs tied
together and touch the other ohmmeter lead in turn to
each tuner antenna input, exposed terminal screw
and, if applicable, to the coaxial connector. If the
measured resistance is less than 1.0 megohms or
greater than 5.2 megohms, an abnormality exists that
must be corrected before the instrument is returned to
the customer. Repeat this test with the instrument AC
switch in the off position.
d.
Leakage Current Hot Check - Plug the AC line cord
directly into a 120V AC 60Hz outlet (do not use an
isolated transformer for this check). Turn the A C
power ON. Using a Leakage Current Tester (Simpson’s
Model 228 or equivalent), measure for current from all
exposed metal parts of the cabinet (antennas,
screwheads, overlays, control shafts, etc.)
particularly any exposed metal part
having a return path to the chassis or to a
known earth ground (water pipe, conduit, etc.). Any
current measured must not exceed 0.5 MIU.
e. High Voltage – This receiver is provided with a
hold down circuit for clearly indicating that voltage has
increased in excess of a predetermined value.
Comply will all notes described in this Service Manual
regarding this hold down circuit when servicing, so
that this hold down circuit may correctly be operated.
f. Service Warning – With maximum contrast, operating
high voltage in this receiver is lower than 30.5 kV. In
case any component having influence on high voltage
is replaced, confirm that the high voltage with
maximum contrast is lower than 30.5 kV.
To measure H.V. use a high impedance H.V. meter.
Connect (-) to chassis earth and (+) to the CRT anode
button. (See the following connection diagram.)
Note: Turn power switch off without fail before the
connection to the anode button is made.
Chassis
ground
High Impedance
H.V. meter
Deflection P.W.B.
FBT
(TH01)
High voltage
connector
+ -
LEAKAGE
CURRENT
TESTER
DEVICE
UNDER
TEST
TEST ALL
EXPOSED
METAL
SURFACES
2-WIRE CORD
(READING
SHOULD NOT
BE ABOVE
0.5 mA)
EARTH
GROUND
ALSO TEST WITH
PLUG REVERSED (USING
AC ADAPTER PLUS
AS REQUIRED)
AC LEAKAGE TEST
ANY MEASUREMENTS NOT WITHIN THE LIMITS
OUTLINED ABOVE ARE INDICATIVE OF A POTENTIAL
SHOCK HAZARD AND MUST BE CORRECTED BEFORE
RETURNING THE RECEIVER TO THE CUSTOMER.
(READING
SHOULD NOT
BE ABOVE
0.5 MIU)
AC Leakage Test