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NOTICE:
Comply with all cautions and safety-related
notes located on or inside the cabinet and on the chasis or
picture tube.
WARNING: Since the chasis of this receiver is connected
to one side of the AC power supply during operation,
whenever the receiver is plugged in, service should not be
attempted by anyone unfamiliar with the precautions
necessary when working on this type of receiver.
The following precautions should be observed:
1. Do not install, remove, or handle the picture tube in any
manner unless shatterproof goggles are worn. People
not so equipped should be kept away from the picture
tube while handling.
2. When service is required, an isolation transformer
should be inserted between power line and the receiver
before any service is performed on a "HOT" chassis
receiver.
3. When replacing a chassis in the receiver, all protective
devices must be put back in place, such as barriers,
nonmetallic knobs, adjustment and compartment
covershields, isolation resistors, capacitors, etc.
4. When service is required, observe the original lead
dress in the high voltage circuitry area.
5. Always
use
the
components. Critical components as indicated on the
circuit diagram should not be replaced by another
manufacturer's. Furthermore, where a short circuit has
occurred, replace those components that indicate
evidence of overheating.
6. Before returning a serviced receiver to the customer, the
service technician must thoroughly test the unit to be
certain that it is completely safe to operate without
danger of electrical shock, and be sure that no
protective device built into the receiver has become
defective, or inadvertently defeated during servicing.
Therefore, the following checks should be performed for
the continued
protection of the customer and service
technician.
Leakage Current Cold Check
With the AC plug removed from the 120V AC 60Hz source,
place a jumper across the two plug prongs. Turn the AC
power switch ON. Using an insulation tester (DC500V),
connect one lead to the jumpered AC plug and touch the
other lead to each exposed metal part (antennas,
screwheads,
metal
overlays,
particularly any exposed metal part having a return path to
the chassis should have a minimum resistor reading of
0.24M
and a maximum resistor reading of 12M . Any
resistance value below or above this range indicates an
abnormality which requires corrective action. An exposed
metal part not having a return path to the chassis will
indicate an open circuit.
SAFETY PRECAUTIONS
manufacturer's
replacement
control
shafts,
etc.),
Leakage Current Hot Check
Plug the AC cord directly into a 120V AC 60Hz outlet (do
not use an isolated transformer for this check). Turn the
AC power ON.
Using a Leakage Current Tester
(Simpson's Model 229 or equivalent), measure for current
from all exposed metal parts of the cabinet (antennas,
screwheads, overlays, control shafts, etc.). Any current
measured must not exceed 0.5 milliamps.
DEVICE
UNDER
TEST
2-WIRE CORD
ALSO TEST WITH
PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED)
AC LEAKAGE TEST
ANY MEASUREMENTS NOT WITHIN THE LIMITS
OUTLINED
ABOVE
POTENTIAL SHOCK HAZARD AND MUST BE
CORRECTED
BEFORE
RECEIVER TO THE CUSTOMER.
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 with all notes described in
this service manual regarding this hold down circuit when
servicing, so that this hold down circuit is operated
correctly.
Serviceman Warning
With
minimum
SHARPNESS, and COLOR, the operating high voltage in
this receiver is lower than 28.30kV ±1.25kV. In case any
component having influence on the high voltage is
replaced, confirm that high voltage with minimum
BRIGHTNESS, CONTRAST, SHARPNESS, and COLOR
is lower than 28.30kV ±1.25kV. To measure high voltage
use a High Impedance High Voltage meter. Connect (-) to
chassis earth and (+) to the CRT ANODE button. (See the
connection diagram on page 4.)
Note:
Turn power switch OFF without fail before the
connection to the Anode Button
- 2 -
(READING
SHOULD NOT BE
ABOVE 0.5mA)
LEAKAGE
CURRENT
TESTER
TEST ALL
EXPOSED METAL
+
SURFACES
EARTH
GROUND
ARE
INDICATIVE
RETURNING
BRIGHTNESS,
CONTRAST,
-
OF
A
THE
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