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20PL83
SERVICE MANUAL
S49F614LK20A/
P
COLOR TELEVISION
Chassis No. MSA
MODELS 20PL83
In the interests of user-safety (Required by safety regulations in some countries) the set should be restored to its
original condition and only parts identical to those specified should be used.
CONTENTS
Page
» ELECTRICAL SPECIFICATIONS ......................................................................................................... 1
» IMPORTANT SERVICE SAFETY PRECAUTION ................................................................................. 2
» LOCATION OF USER'S CONTROL ..................................................................................................... 4
» INSTALLATION AND SERVICE INSTRUCTIONS ................................................................................ 5
» CHASSIS LAYOUT ............................................................................................................................. 13
» BLOCK DIAGRAM .............................................................................................................................. 14
» SCHEMATIC DIAGRAMS ...................................................................................................................18
» PRINTED WIRING BOARD ASSEMBLIES ........................................................................................ 2 3
» REPLACEMENT PARTS LIST ............................................................................................................ 27
» PACKING OF THE SET ...................................................................................................................... 33
ELECTRICAL SPECIFICATIONS
POWER INPUT ........................................ 110-220 V AC 50/60 Hz
POWER RATING .................................................................7..2 W
PICTURE SIZE .......................................... 1,194 cm2 (185sq inch)
CONVERGENCE ............................................................. Magnetic
SWEEP DEFLECTION .................................................... Magnetic
FOCUS ............................................................... QPF Electrostatic
INTERMEDIATE FREQUENCIES
Picture IF Carrier Frequency ..................................... 45.75 MHz
Sound IF Carrier Frequency ...................................... 41.25 MHz
Color Sub-Carrier Frequency .................................... 42.17 MHz
(Nominal)
AUDIO POWER
OUTPUT RATING....................... 3.0 + 3.0 W (at 10% distortion)
SPEAKER
SIZE ................................................................ 9 × 5 cm (Round)
VOICE COIL IMPEDANCE ........................... 32 ohm at 400 Hz
ANTENNA INPUT IMPEDANCE
VHF/UHF ..................................................... 75 ohm Unbalanced
TUNING RANGES
VHF-Channels ............................................................... 2 thru 13
UHF-Channels ............................................................ 14 thru 69
CATV Channels ........................................................... 1 thru 125
Specifications are subject to c hange without
prior notice.
SHARP COR1 PORATION
http://www.Datasheet4U.com
20PL83
IMPORTANT SERVICE SAFETY PRECAUTION
Ë Service work should be performed only by qualified service technicians who are thoroughly
familiar with all safety checks and the servicing guidelines which follow:
WARNING
1. For continued safety, no modification of an y circuit
should be attempted.
2. Disconnect AC power before servicing.
3. Semiconductor heat sinks are potential shoc k
hazards when the chassis is operating.
4. The chassis in this receiver has two ground systems
which are separated by insulating material. The non-
isolated (hot) g round system is f or the B+ v oltage
regulator circuit and the horizontal output circuit.The
isolated ground system is of r the low B+ DC voltages
and the secondar y circuit of the high v oltage
transformer.
To pre vent electr ical shoc k use an isolation
transf or mer betw een the line cord and po wer
receptacle, when servicing this chassis.
SERVICING OF HIGH VOLTAGE SYSTEM
AND PICTURE TUBE
When servicing the high v oltage system,
remove the static c harge by connecting a
10k ohm resistor in series with an insulated
wire (such as a test probe) between the pic-
ture tube gr ound and the anode lead. (AC
line cord should be disconnected from AC
outlet.)
1. Picture tube in this receievr employs integral implosion
protection.
2. Replace with tube of the same type n umber f or
continued safety.
3. Do not lift picture tube by the neck.
4. Handle the picture tube only when w
ear ing
shatterproof goggles and after discharging the high
voltage anode completely.
X-RADIATION AND HIGH VOLTAGE LIMITS
1. Be sure all ser vice personnel are a ware of the
procedures and instructions covering X-radiation.The
only potential source of X-r ay in current solid state
TV receivers is the picture tube. However, the picture
tube does not emit measur able X-Ray r adiation, if
the high voltage is as specified in the "High Voltage
Check" instructions.
It is only when high v oltage is e xcessive that X-
radiation is capab le of penetr ating the shell of the
picture tube including the lead in the glass material.
The important precaution is to keep the high voltage
below the maximum level specified.
2. It is essential that ser vicemen have available at all
times an accurate high voltage meter.
The calibr ation of this meter should be chec ked
periodically.
3. High voltage should always be kept at the rated value
−no higher. Operation at higher voltages may cause
a failure of the picture tube or high v oltage circuitry
and;also, under cer tain conditions , ma y produce
radiation in exceeding of desirable levels.
4. When the high voltage regulator is operating properly
there is no possibility of an X-ar diation problem. Every
time a color chassis is serviced, the brightness should
be tested while monitor ing the high v oltage with a
meter to be cer tain that the high v oltage does not
exceed the specified v alue and that it is regulating
correctly.
5. Do not use a picture tube other than that specified or
make unrecommended circuit modifications to the
high voltage circuitry.
6. When trouble shooting and taking test measurements
on a receiver with excessive high voltage, avoid being
unnecessarily close to the receiver.
Do not operate the receiver longer than is necessary
to locate the cause of excessive voltage.
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