Safety Instructions - Sanyo Vizon DP32746 Service Manual

SAFETY PRECAUTIONS
WARNING: The chassis of this receiver has a floating ground with the
potential of one half the AC line voltage in respect to earth ground.
Service should not be attempted by anyone not familiar with the
precautions necessary when working on this type of equipment.
The following precautions must be observed:
1. An isolation transformer must be connected in the power line
between the receiver and the AC line before any service is
performed on the receiver.
2. Comply with all caution and safety-related notes provided on the
side of the cabinet, inside the cabinet, and on the chassis.
3. When replacing a chassis in the cabinet, always be certain that all
the protective devices are installed properly, such as control
knobs, adjustment covers, shields and barriers.
4. Before replacing the back cover of the set, thoroughly inspect the
inside of the cabinet to see that no stray parts or tools have been
left inside.
Before returning any television to the customer, the service
technician must perform the following safety checks to be sure
that the unit is completely safe to operate without danger of
electrical shock.
ANTENNA COLD CHECK
Remove AC plug from the 120 VAC outlet and place a jumper
across the two blades. Connect one lead of an ohmmeter to the
jumpered AC plug, and touch the other lead to each exposed antenna
terminal (UHF and VHF antenna terminals). The resistance must
measure between 1M ohm and 5.2M ohm. Any resistance value
below or above this range indicates an abnormality which requires
corrective action.
LEAKAGE CURRENT CHECK
P
lug the AC line cord directly into a 120 VAC outlet. (Do not use an
isolation transformer for this check.) Use an AC voltmeter, that has
5000 ohms per volt or more sensitivity. Connect a 1500 ohm 10 watt
resistor, paralleled by a 0.15 µF 150 VAC capacitor, between a
known good earth ground (water pipe, conduit, etc.) and all
exposed metal parts of the cabinet (antennas, handle bracket, metal
cabinet, screw heads, metal overlays, control shafts, etc.). Measure
the AC voltage across the 1500 ohm resistor. The AC voltage should
not exceed 750 mV. A reading exceeding 750 mV indicates that a
dangerous potential exists. The fault must be located and correct-
ed. Repeat the above test with the receiver power plug reversed.
NEVER RETURN A RECEIVER TO THE CUSTOMER WITHOUT
TAKING THE NECESSARY CORRECTIVE ACTION.
READING SHOULD NOT EXCEED 750 mV.
(5000 ohms per volt or more sensitivity)
TELEVISION
RECEIVER
AC OUTLET
To be touched to all of exposed metal parts.
Voltmeter Hook-up for Leakage Current Check.

SAFETY INSTRUCTIONS

AC VOLTMETER
Good earth ground
1500 ohm such as a water pipe,
10 watt
conduit, etc.
0.15 µF 150V AC
PRODUCT SAFETY NOTICE
W
hen replacing components in a receiver, always keep in mind
the necessary product safety precautions. Pay special attention
to the replacement of components marked with a star (#) in the
parts list and in the schematic diagrams. To ensure safe product
operation, it is necessary to replace those components with the
.
exact same PARTS
SERVICING ELECTROSTATICALLY SENSATIVE DEVICES
Semiconductors (solid-state devices) that can be damaged by static
electricity are referred to as Electrostatically Sensitive (ES) devices.
Examples of typical ES devices are: Integrated Circuits (IC), Field-
Effect Transistors (FET), and "chip" components. The following
techniques should be observed strictly, to reduce the occurrence of
semiconductor damage due to electrostatic discharge.
1. Immediately prior to handling any semiconductor component or
an assembly containing a semiconductor device or devices, dis-
charge the electrostatic buildup on your body by touching a
known earth ground. You may also obtain and wear a commer-
cially available discharging wrist strap device.
CAUTION: Be sure to remove the wrist strap before applying
power to any unit being serviced.
2. After removing an ES equipped assembly, place it on a conduc-
tive surface, such as, aluminum foil, to prevent buildup or
exposure to static electricity.
3. Use only grounded-tip soldering irons to solder or unsolder ES
devices.
4. Use only anti-static solder removal devices. Some suction-type
devices can generate static electricity adequate to damage ES
devices.
5. A replacement ES device will come packaged in protective material
(conductive foam, aluminum foil, or some comparable conductive
material). Do Not remove an ES device from its protective packag-
ing unless you are prepared to install it immediately.
6. Precisely prior to removing an ES device from its protective pack-
aging, touch the protective packaging to the chassis or
assembly in which the device will be install
CAUTION: Be sure that no power is applied to the chassis or circuit
assembly.
7. Incidental body movements, such as, lifting a foot from a carpeted
floor or the rubbing of fabric together can generate static electricity
sufficient to damage ES devices. Therefore, minimize all body
movements while handling exposed (unpackaged) ES devices.
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