Service Manuals, User Guides, Schematic Diagrams or docs for : ZENITH Proj TV R56W28 ZP28 chassis zenith_zp26-28-rear

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SERVICE MANUAL
Model Series:
Product Type: Digital Rear Projection R50V26
Chassis: ZP26/28 R56W28
Manual Series: PV154 R60V26
Manual Part #: 923-03506 R65W28
Model Line: E
Product Year: 2002

CONTENTS
General Info ................................................. 1
Service Menu ................................................ 2
Servicing ..................................................... 3
Part List ...................................................... 4
Diagrams / PCB Layouts .................................. 5
Schematics ................................................... 6

Published August 2002
by Technical Publications
Zenith Electronics Corporation
201 James Record Road
Huntsville, Alabama 35824-1513

Printed in U.S.A.
PRODUCT SAFETY SERVICING GUIDELINES FOR AUDIO-VIDEO PRODUCTS
IMPORTANT SAFETY NOTICE
This manual was prepared for use only by properly trained audio-video service A.C. Voltmeter
technicians.
When servicing this product, under no circumstances 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 original layout upon completion of repairs.
Special components are also used to prevent x-radiation, shock and fire hazard.
These components are indicated by the letter "x" included in their component 0.15uF
Place this probe
Good Earth Ground
designators and are required to maintain safe performance. No deviations are on each exposed
such as the Water
allowed without prior approval by Zenith Electronics Corporation. 1500 OHM metal part.
Pipe, Conduit, etc.
Circuit diagrams may occasionally differ from the actual circuit used. This way,
implementation of the latest safety and performance improvement changes into 10 WATT
the set is not delayed until the new service literature is printed.

CAUTION: Do not attempt to modify this product in any way. Never perform X-RADIATION
customized installations without manufacturer's approval. Unauthorized 1. Be sure procedures and instructions to all service personnel cover the
modifications will not only void the warranty, but may lead to property damage subject of x-radiation. The only potential source of x-rays in current TV
or user injury. receivers is the picture tube. However, this tube does not emit x-rays when
the HV is at the factory-specified level. The proper value is given in the
Service work should be performed only after you are thoroughly familiar with
applicable schematic. Operation at higher voltages may cause a failure of
these safety checks and servicing guidelines.
the picture tube or high-voltage supply and, under certain circumstances
may produce radiation in excess of desirable levels.
GRAPHIC SYMBOLS
2. Only factory-specified CRT anode connectors must be used.
The exclamation point within an equilateral triangle is intended
to alert the service personnel to important safety information in 3. It is essential that the service personnel have available an accurate and
the service literature. reliable high-voltage meter.

The lightning flash with arrowhead symbol within an equilateral 4. When the high-voltage circuitry is operating properly, there is no possibility
triangle is intended to alert the service personnel to the presence of an x-radiation problem. Every time a chassis is serviced, the brightness
of noninsulated "dangerous voltage" that may be of sufficient should be run up and down while monitoring the high voltage with a
magnitude to constitute a risk of electric shock. meter, to be certain that the high voltage does not exceed the specified
value and that it is regulating correctly.
The pictorial representation of a fuse and its rating within an
5. When troubleshooting and making test measurements in a product with a
equilateral triangle is intended to convey to the service personnel
problem of excessively high voltage, avoid being unnecessarily close to
the following fuse replacement caution notice:
the picture tube and the high voltage power supply. Do not operate the
CAUTION: FOR CONTINUED PROTECTION AGAINST RISK OF FIRE,
product longer than necessary to locate the cause of excessive voltage.
REPLACE ALL FUSES WITH THE SAME TYPE AND RATING AS MARKED
NEAR EACH FUSE. 6. Refer to HV, B+, and shutdown adjustment procedures described in the
appropriate schematics and diagrams (where used).
SERVICE INFORMATION
While servicing, use an isolation transformer for protection from AC line shock. IMPLOSION
After the original service problem has been corrected, make a check of the 1. All direct view picture tubes are equipped with an integral implosion
following: protection system; take care to avoid damage during installation.
2. Use only the recommended factory replacement tubes.
FIRE AND SHOCK HAZARD
1. Be sure that all components are positioned to avoid a possibility of TIPS ON PROPER INSTALLATION
adjacent component shorts. This is especially important on items trans- 1. Never install any receiver in a closed-in recess, cubbyhole, or closely
ported to and from the repair shop. fitting shelf space over, or close to, a heat duct, or in the path of heated
2. Verify that all protective devices such as insulators, barriers, covers, air flow.
shields, strain reliefs, power supply cords, and other hardware have been 2. Avoid conditions of high humidity such as: outdoor patio installations
reinstalled per the original design. Be sure that the safety purpose of the where dew is a factor, near steam radiators where steam leakage is a factor,
polarized line plug has not been defeated. etc.
3. Soldering must be inspected to discover possible cold solder joints, solder 3. Avoid placement where draperies may obstruct venting. The customer
splashes, or sharp solder points. Be certain to remove all loose foreign should also avoid the use of decorative scarves or other coverings that
particles. might obstruct ventilation.
4. Check for physical evidence of damage or deterioration to parts and compo- 4. Wall- and shelf-mounted installations using a commercial mounting kit
nents, for frayed leads or damaged insulation (including the AC cord), and must follow the factory-approved mounting instructions. A product mounted
replace if necessary. to a shelf or platform must retain its original feet (or the equivalent
thickness in spacers) to provide adequate air flow across the bottom. Bolts
5. No lead or component should touch a high current device or a resistor or screws used for fasteners must not touch any parts or wiring. Perform
rated at 1 watt or more. Lead tension around protruding metal surfaces leakage tests on customized installations.
must be avoided.
5. Caution customers against mounting a product on a sloping shelf or in a
6. After reassembly of the set, always perform an AC leakage test on all exposed tilted position, unless the receiver is properly secured.
metallic parts of the cabinet (the channel selector knobs, antenna terminals,
6. A product on a roll-about cart should be stable in its mounting to the cart.
handle and screws) to be sure that set is safe to operate without danger of
Caution the customer on the hazards of trying to roll a cart with small
electrical shock. DO NOT USE A LINE ISOLATION TRANSFORMER DURING THIS
casters across thresholds or deep pile carpets.
TEST. Use an AC voltmeter having 5000 ohms per volt or more sensitivity in
the following manner: Connect a 1500 ohm, 10 watt resistor, paralleled by 7. Caution customers against using a cart or stand that has not been listed
a .15 mfd 150V AC type capacitor between a known good earth ground by Underwriters Laboratories, Inc. for use with its specific model of
water pipe, conduit, etc.) and the exposed metallic parts, one at a time. television receiver or generically approved for use with TVs of the same or
Measure the AC voltage across the combination of 1500 ohm resistor and larger screen size.
.15 mfd capacitor. Reverse the AC plug by using a non-polarized adaptor 8. Caution customers against using extension cords. Explain that a forest of
and repeat AC voltage measurements for each exposed metallic part. Voltage extensions, sprouting from a single outlet, can lead to disastrous
measured must not exceed 0.75 volts RMS. This corresponds to 0.5 milliamp consequences to home and family.
AC. Any value exceeding this limit constitutes a potential shock hazard and
must be corrected immediately.

PV154 - 923-03506 i ZP26/28 - SAFETY
PRODUCT SAFETY SERVICING GUIDELINES FOR AUDIO-VIDEO PRODUCTS
CRT ANODE HIGH VOLTAGE MEASUREMENT PROCEDURE 5. Do not use freon-propelled chemicals. These can generate electri-
cal charge sufficient to damage ES devices.
To prevent possible exposure to radiation caused by excessive CRT
Anode voltage, the High Voltage Shutdown circuit senses the level 6. Do not remove a replacement ES device from its protective pack-
of flyback pulse from "Flyback Transformer" representative of the age until immediately before you are ready to install t.(Most replace-
actual high voltage on the CRT anode. When this level exceeds a ment ES devices are packaged with leads electrically shorted to-
predetermined voltage, the circuit shuts down the horizontal drive, gether by conductive foam, aluminum foil, or comparable conduc-
preventing further generation of anode voltage. In this condition, tive material.)
the horizontal drive is "latched" off. The drive will remain off until 7. Immediately before removing the protective material from the
power (via remote control or front panel) is re-cycled from "Off" to leads of a replacement ES device, touch the protective material to
"On". the chassis or circuit assembly into which the device will be in-
Critical Safety components (designated with an "X" in the compo- stalled.
nent designator) are designed to operate the CRT at a safe operating Caution: Be sure no power is applied to the chassis or circuit, and
Anode voltage and provide proper shutdown thresholds . If replace- observe all other safety precautions.
ment of any of these components are deemed necessary, it is impor- 8. Minimize bodily motions when handling unpackaged replace ment
tant to use original type Zenith replacement components. After ES devices. (Otherwise, seemingly harmless motion, such as the brush-
replacement is made, confirm proper Anode voltage using the fol- ing together of your clothing or the lifting of your foot from a
lowing procedure. carpeted floor, can generate static electricity sufficient to damage
Measurement of the CRT Anode voltage must be performed using a an ES device.)
high impedance high voltage meter, with no visible raster on the REGULATORY INFORMATION
screen, and operating at nominal horizontal scanning frequency.
Connect a strong broadcast signal (or TV signal generator operating This equipment has been tested and found to comply with the limits
at 15.734kHz horizontal scanning rate) to the RF input. for a Class B digital device, pursuant to Part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against
After discharging the CRT, connect a high impedance high voltage harmful interference when the equipment is operated in a residential
meter to the CRT anode. Turn the television "on" and confirm a good installation. This equipment generates, uses and can radiate radio
signal is being displayed . Reduce Brightness and Contrast settings frequency energy and, if not installed and used in accordance with
until the picture is well extinguished. If the voltage reading is the instruction manual, may cause harmful interference to radio
higher than the maximum, verify circuit component values and communications. However, there is no guarantee that interference
proper operation. will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which
B+ VDC HV NOM HV MAX
can be determined by turning the equipment off and on, the user is
(0 BEAM) KV KV
encouraged to try to correct the interference by one or more of the
115 +/- 2% 30.2 30.5 following measures: Reorient or relocate the receiving antenna; In-
SHUTDOWN TEST PROCEDURE crease the separation between the equipment and receiver; Connect
the equipment into an outlet on a circuit different from that to
Equipment needed is a video generator, HV DC meter (0 to 40 KV,
which the receiver is connected; Consult the dealer or an experi-
high Z), and a external variable power supply (0V to 6VDC @ 5Amps
enced radio/TV technician for help.
minimum).
The presence of the DTV certification mark indicates that this prod-
To verify the Shutdown Circuit is operating properly, Supply +6V DC
uct will successfully receive digital television transmissions that
to pin 1 of P1407 and ground to Heat sink of Q1413. If there is no
conform to any and all of the video formats described in the ATSC
raster and set goes into Shutdown, then the Shutdown Circuit is
Digital Television Standard.
functional. If the set doesn't go into Shutdown, then the Circuit is
defective. The responsible party for this device's compliance is:
Zenith Electronics Corporation
ELECTROSTATICALLY SENSITIVE DEVICES 201 James Record Road
Some semiconductor (solid-state) devices can be damaged easily by Huntsville, AL 35824, USA
static electricity. Such components commonly are called Electro- Digital TV Hotline: 1-800-243-0000
statically Sensitive (ES) Devices. Examples of typical ES devices are
integrated circuits and some field-effect transistors and semicon- TRADEMARKS USED IN THIS MANUAL
ductor "chip" components. The following techniques should be Dolby Digital

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