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PRODUCT SAFETY SERVICING GUIDELINES FOR AUDIO-VIDEO PRODUCTS
CRT ANODE HIGH VOLTAGE MEASUREMENT PROCEDURE
To prevent possible exposure to radiation caused by excessive CRT
Anode voltage, the High Voltage Shutdown circuit senses the level
of flyback pulse from "Flyback Transformer" representative of the
actual high voltage on the CRT anode. When this level exceeds a
predetermined voltage, the circuit shuts down the horizontal drive,
preventing further generation of anode voltage. In this condition,
the horizontal drive is "latched" off. The drive will remain off until
power (via remote control or front panel) is re-cycled from "Off" to
"On".
Critical Safety components (designated with an "X" in the compo-
nent designator) are designed to operate the CRT at a safe operating
Anode voltage and provide proper shutdown thresholds . If replace-
ment of any of these components are deemed necessary, it is impor-
tant to use original type Zenith replacement components. After
replacement is made, confirm proper Anode voltage using the fol-
lowing procedure.
Measurement of the CRT Anode voltage must be performed using a
high impedance high voltage meter, with no visible raster on the
screen, and operating at nominal horizontal scanning frequency.
Connect a strong broadcast signal (or TV signal generator operating
at 15.734kHz horizontal scanning rate) to the RF input.
After discharging the CRT, connect a high impedance high voltage
meter to the CRT anode. Turn the television "on" and confirm a good
signal is being displayed . Reduce Brightness and Contrast settings
until the picture is well extinguished. If the voltage reading is
higher than the maximum, verify circuit component values and
proper operation.
B+ VDC
HV NOM
(0 BEAM)
K V
115 +/- 2%
30.2
SHUTDOWN TEST PROCEDURE
Equipment needed is a video generator, HV DC meter (0 to 40 KV,
high Z), and a external variable power supply (0V to 6VDC @ 5Amps
minimum).
To verify the Shutdown Circuit is operating properly, Supply +6V DC
to pin 1 of P1407 and ground to Heat sink of Q1413. If there is no
raster and set goes into Shutdown, then the Shutdown Circuit is
functional. If the set doesn't go into Shutdown, then the Circuit is
defective.
ELECTROSTATICALLY SENSITIVE DEVICES
Some semiconductor (solid-state) devices can be damaged easily by
static electricity. Such components commonly are called Electro-
statically Sensitive (ES) Devices. Examples of typical ES devices are
integrated circuits and some field-effect transistors and semicon-
ductor "chip" components. The following techniques should be
used to help reduce the incidence of component damage caused by
static electricity.
1. Immediately before handling any semiconductor component or
semiconductor-equipped assembly, drain off any electrostatic charge
on the body by touching a known earth ground. Alternatively, ob-
tain and wear a commercially available discharging wrist strap de-
vice, which should be removed for potential shock reasons prior to
applying power to the unit under test.
2. After removing an electrical assembly equipped with ES devices,
place the assembly on a conductive surface such as an ESD mat, to
prevent electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ES
devices.
4. Use only an anti-static solder removal device. Some solder re-
moval devices not classified as "anti-static" can generate electrical
charges sufficient to damage ES devices.
PV154 - 923-03506
HV MAX
K V
30.5
ii
5. Do not use freon-propelled chemicals. These can generate electri-
cal charge sufficient to damage ES devices.
6. Do not remove a replacement ES device from its protective pack-
age until immediately before you are ready to install t.(Most replace-
ment ES devices are packaged with leads electrically shorted to-
gether by conductive foam, aluminum foil, or comparable conduc-
tive material.)
7. Immediately before removing the protective material from the
leads of a replacement ES device, touch the protective material to
the chassis or circuit assembly into which the device will be in-
stalled.
Caution: Be sure no power is applied to the chassis or circuit, and
observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged replace ment
ES devices. (Otherwise, seemingly harmless motion, such as the brush-
ing together of your clothing or the lifting of your foot from a
carpeted floor, can generate static electricity sufficient to damage
an ES device.)
REGULATORY INFORMATION
This equipment has been tested and found to comply with the limits
for a Class B digital device, pursuant to Part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against
harmful interference when the equipment is operated in a residential
installation. This equipment generates, uses and can radiate radio
frequency energy and, if not installed and used in accordance with
the instruction manual, may cause harmful interference to radio
communications. However, there is no guarantee that interference
will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which
can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the
following measures: Reorient or relocate the receiving antenna; In-
crease the separation between the equipment and receiver; Connect
the equipment into an outlet on a circuit different from that to
which the receiver is connected; Consult the dealer or an experi-
enced radio/TV technician for help.
The presence of the DTV certification mark indicates that this prod-
uct will successfully receive digital television transmissions that
conform to any and all of the video formats described in the ATSC
Digital Television Standard.
The responsible party for this device's compliance is:
Zenith Electronics Corporation
201 James Record Road
Huntsville, AL 35824, USA
Digital TV Hotline: 1-800-243-0000
TRADEMARKS USED IN THIS MANUAL
Dolby Digital® Manufactured under license from Dolby Laboratories.
"Dolby" and the double-D symbol are trademarks of Dolby Laborato-
ries. Confidential Unpublished Works. ©1992-1997 Dolby Laborato-
ries, Inc. All rights reserved.
VCR Plus+, PlusCode and GUIDE Plus+ are trademarks of Gemstar
Development Corporation. The VCR Plus+ and GUIDE Plus+ systems
are manufactured under license from Gemstar Development Corpora-
tion and VCR Index Systems B.V., respectively.
Gemstar is not in any way liable for the accuracy of the program
schedule information provided by the GUIDE Plus+ system. In no
event shall Gemstar be liable for any amounts representing loss of
profits, loss of business, or indirect, special, or consequential dam-
ages in connection with the provision or use of any informaion,
equipment, or services relating to the GUIDE plus+ system.
SRS and the symbol are trademarks of SRS labs, Inc. SRS technology
is incorporated under license from SRS Labs, Inc.
Licensed by BBE Sound, Inc. under USP4638258 and 4482866. BBE
and the symbol are registered trademarks of BBE Sound, Inc.
ZP26/28 - SAFETY
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