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Sharp 8C221 Service Manual
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Sharp 8C221 Service Manual

Sharp 8C221 Service Manual

Pal system colour tv
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P A L S Y S T E M
C O L O U R TELEWSION
Aerial Input Imp'edance . . . . . . . . . . . . . . . . . . 75 ohm
Convergence. . . . . . . . . . . . . . . . Self Converging System
Focus . . . . . . . . . . . . . . . . . . . Bi-potential electrostatic
Audio Power Output Rating . . . . . . . . . . 2.0 Watt (max.)
Intermediate Frequencies
Picture IF Carrier Frequency. . . . . . . . . . 36,875 MHz
Sound IF Carrier Frequency . . . . . . . . . . 31,375 MHz
Maintenance and repair of this receiver should be down by
qualified service persona4 only.
SERVICING OF HIGH VOLTAGE SYSTEM AND
PICTURE TUBE
When servicing the high voltage system, remove static
charge from it by connecting a 1 OK ohm Resistor in series
with an insulated wire (such as a test probe) between picture
tube dag and 2nd anode lead. (AC line cord shodd be
disconnected from AC outlet.)
1. Picture tube in this receiver employs ixitegral implosion
protection.
ed safety.
3.
not lift picture tube by the neck.
Do
4. Handle the picture tube only when wearing shatter-proof
goggles and after discharging the high voltage completely.
The manufacturer reserves the right to vary specifications or use alternative materials as may be deemed necessary or desirable
at any time, any such change or variation being of a kind as not to reduce the quality performance or appearance substantially.
S H A R P
ELECTRICAL SPECIFICATIONS
IMPORTANT SERVICE NOTES
C O R P O R A T I O N
64-80 SEVILLE ST.,
FAIRFIELD, 2165
Power Rating . . . . . . . . . . . . . . . . . . . . . . . .
Speaker Size. . . . . . . . . . . . . . . . . . 19 x 10cm Dynamic
Voice Coil Impedance . . . . . . . . . . . .8 ohms (at 400 Hz)
Sweep Deflection . . . . . . . . . . . . . . . . . . . . . .Magnetic
Tuning Ranges . . . . . . . . . . . . . VHF-Channels 0 thru 11
X-RAY
This receiver is designed so that any X-ray radiation is
kept to an absolute minimum. Since certain malfunctions
or servicing may produce potentially hazardous radiation
with prolonged exposure at close range, the following
precautions should be observed:
1.
not adjust the high voltage level above 27.5 KV at
Do
1 .lmA.
2.
substitute a picture tube with unauthorized
Do not
types and/or brands which may cause excess X-ray
radiation.
BEFORE RETURNING THE RECEIVER
Before returning the receiver to the user, perform the
following safety checks.
1. Inspect all lead dress to make certain that leads are nol
pinched or that hardware is not lodged between the
chassis and other metal parts in the receiver.
2. Inspect al4 protective devices such as non-metal4ic control
knobs, insulating fishpapers, cabinet
and compartment covers or shields, isolation resistor-
capacity networks, mechanical insulators etc.
O F
TEL: 02-728-9111
165 Watt
backs, adjustment
L T D .

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Summary of Contents for Sharp 8C221

  • Page 1 P A L S Y S T E M C O L O U R TELEWSION ELECTRICAL SPECIFICATIONS Aerial Input Imp’edance ....75 ohm Power Rating .
  • Page 2 INSTALLATION AND SERVICE ADJUSTMENTS NEW COLOUR TELEVISION INSTALLATION OF RECEIVER Touch the Channel Selector Button corresponding to Adjust the receiver for a black and white picture. Check the channel, that you wish to select. the horizontal oscillator adjustment, focus, vertical size Observe the picture for good black-and- and linearity.
  • Page 3 High voltage is not adjustable but must be checked to The +13OV Adj. control (R724) is adjusted at the factory. verify that the receiver is operating within safe and efficient However, should readjustment be required, proceed follows: design limitations specified: Remove cabinet back.

  • Page 4: White Balance Adjustment

    WHITEBALANCE ADJUSTMENT PURITYADJUSTMENT The purpose of this procedure is to optimize the picture Before purity adjustment can be made, the receiver tube to obtain good black and white picture at all brightness should be demagnetized and allow to run with full bright- levels while at the same time achieving maximum usable ness (without bloom) for a minimum of 10 minutes and brightness.

  • Page 5: Chassis Removal

    Static Convergence Adjustment PICTURE TUBE ASSEMBLY REMOVAL AND REPLACE- MENT tions reverse to each other so as to make the same the Remove PWB-B and PWB-E chassis from cabinet. vertical lines of red beam and blue beam. (Refer to CHASSIS REMOVAL procedure) Disconnect picture tube coating earth tip from the PWB- the created angle between them and fix them when the vertical line and horizontal line for both red beam and...
  • Page 6 Equipment connected from the oscilloscope probe to ground will eliminate stray pick-up of unwanted signals. If used, make The test equipment specified on page 7 or its equivalent, sure the capacitor does not affect the shape of the response is required to properly perform the alignment procedures being observed.

  • Page 7: Test Equipment

    TESTEQUIPMENT To facilitate service and alignment for this chassis, it is SWEEP GENERATOR. MARKER GENERATOR ..With crystal caliblated used. accuracy. VARIABLE POWER SUPPLY ..Range: DC 0 . . .25V TEST PATTERN GENERATOR IF-TEST BLOCKS .
  • Page 8 TUNER PERFORMANCE CHECK Preliminary Information OSCILLOSCOPE . . . With at 1 .OV P-P calibration, connect to terminal TP203. Unless there is evidence of tempering or if electrical repairs SWEEP GENERATOR ..Connect output to the tuner have been made tuner alignment is normally not required. aerial terminals using proper matching pad.
  • Page 9 PICTURE IF TRANSFORMER & TRAP ALIGNMENT MARKER GENERATOR ..Couple loosely to Sweep Test Equipment Connections: Refer to Figure 7. GENERAL ....Connect AC power plug through Generator Output Cable to provide markers.
  • Page 10 3 1.375 Response Curve %” Response Curve “A” Figure 7. PIF Transformer and Trap Alignment...

  • Page 11: Alignment Procedure

    RF AFT ALIGNMENT Note: Set base line in centre of CRT for reference. Test Equipment Connections* Refer to Figure 9 . SWEEP GENERATOR ..Connect the IF video output GENERAL ....Set channel selector to the highest through the Output Pad or B.
  • Page 12 0 TP205 Figure 9. RF AFT Alignment...
  • Page 13 The following alignment procedures are accomplished with the receiver operating normally while connected to an antenna and tuned to receiver a local telecast. STEP ADJUSTMENT COMPONENT PROCEDURE Transformer Input Adjust the input transformer for maximum sound. Adjust the discriminator for least distortion with maximum Discriminator sound and minimum buzz.
  • Page 14 PEDESTAL LEVEL ALIGNMENT in a black and White Signal. The receiver should Connect AC power plug through the isolation transformer Tune to power supply. have been operating at least 10 minutes before proceeding with Pedestal Level Alignment. PROCEDURE STEP Set the Brightness control to mid. positions. Set the R-Drive, G-Drive and B-Drive controls to mid range.
  • Page 15 Test Equipment Connections: OSCILLOSCOPE ..Connect to TP802 through “Video Refer to Figure 12. GENERAL ..Connect AC power plug through the Detector Test Block” shown in Figure 4. isolation transformer to power supply.
  • Page 16 OSCILLOSCOPE ... . Connect through direct probe Test Equipment Connections: Refer to Figure 13. described. The frequency response of vertical input GENERAL ..Connect AC power plug through the isola- should be flat to at least MHz.
  • Page 17 COMPONENT STEP ADJUSTMENT PROCEDURE Set the Colour control to centre of its range. Connect Oscilloscope to TP803. Adjust Delay Time Adjust R821 to the response curve “A” shown in Figure 14. control Adjust Phase trans. Adjust T804 to the response curve “B” shown in Figure 14. Remove Oscilloscope to TP804.

  • Page 18: Troubleshooting Guide

    TROUBLE SHOOTING GUIDE PRECAUTIONS TO BE TAKEN DURING REPLAIR Methods of Checking In servicing, some of the methods used for valve systems Repairs will be considerably simplified by careful observa- do not work on solid state colour T.V. receivers. Keep in tion of the defect and its location to a specific part of the mind that:- circuit.
  • Page 19 These notes may give the impression that the repair of (a) Burn-out Layer short - line short - iron core short . . . etc. However, no difficulties should be encountered provided that it is remembered that extra care must be taken in CHECKING OF TRANSISTORS BY OHMMETER Transistors can be checked by measuring the forward EXAMPLES OF DEFECTIVE PARTS...
  • Page 20 EXPLANATION OF CODES FOR RESISTOR AND CAPACITOR RESISTOR DECIMAL MULTIPLIER EXAMPLE SIGNIFICANT FIGURES TOLERANCE (POWER OF 10) (RESISTANCE) BROWN ORANGE YELLOW GREEN BLUE VIOLET GRAY WHITE GOLD SILVER COLORLESS A : RED EXAMPLE B : VIOLET = 27,OOOa C : ORANGE D : CX)LD CAPACITOR EXAMPLE...

  • Page 21: Troubleshooting Table

    TROUBLE SHOOTING TABLE Power Regulator Circuit Horizontal Deflection Circuit Picture Tube Bias Circuit Protector Video Circuit Picture Tube Replace the fuse Check for the collector with new one. voltage of 0705. again our again r - m - - - J - - - - - 1 i - - - - - - - - - - - y - - - - - - - - B -...
  • Page 22 P-l F Circuit . T u n e r B power supply circuit for the tuner to the pin 1 of 1201, does noise appear on the screen? Check for the voltage at the Make the pin 9 of base, collector and emitter of Q207.
  • Page 23 NO PICTURE (SOUND IS NORMAL) Checked Circuit Video A 7plifier Check for the voltage at the collector, emitter and base of Q208 and Q209. Normal Make TP804 be grounded. Normal (12.5V) --VW- If the both legs of R457 are shorted, does picture appear? Checked Circuits Audio Output Circuit...
  • Page 24 Are both vertical and horizontal synchronizations not possible? Only horizontal synchronization synchronization Check for the voltage at the collector, base and emitter of 09. Is it impossible aven if H-HOLD (R618) Is it impossible even and H-FREQ (R617) if V-HOLD (R506) controls are adjusted? Check for the voltage at the collector, base and emitter...
  • Page 25 NO VERTICAL SCAN s e t a t S E R V I C E posItIon? At “NORM;L” position Check Q503 base voltage. Normal: 2V,-, - - - Normal Voltage Normal: 11.6V Deflection coil - - - I - - DEFECTIVE VERTICAL AMPLITUDE AND VERTICAL LINEARITY Adjust the controls - - e m - _ _ - -...
  • Page 26 NO COLOUR OR PALE COLOUR Checked Circuits No colour When the junction bet. shorted, does colour No colour Is there chroma signal at Check for the voltage at the collector, emitter and base of 0801. When the emitter-collector junction of Q802 is shorted, does colour - -I...
  • Page 27 NO SPECIFIC COLOUR Specific colours are not produced in colour broad- Checked Circuits cast reception. Is some colour produced in B/W broadcast reception? Is the white balance properly adjusted? r----- The picture coloured blue The picture coloured green The picture coloured red or yellow.

  • Page 28: Printed Wiring Board Assemblies

    PRINTED WIRING BOARD ASSEMBLIES Figure 18. PWB-A Component Side...
  • Page 29 Figure 19. PWBA Wiring Side...
  • Page 30 Figure 20. FWB-B Component Side...
  • Page 31 Figure 21. PWB-B Wiring Side...
  • Page 33 Figure 26. PWB-E Component Side Figure 27. PWB-E Wiring Side...
  • Page 34 Figure 28. PWM-A Component Side Figure 29. PWM-A Wiring Side...
  • Page 35 CHASSIS I EL SELECTOR BUT TON D-L-AMP-AD J . R821 SUB-CONTRAST PEDESTAL LEVEL SET Figure 30. 1:...
  • Page 36 G-DRIVE B-DRIVE...
  • Page 37 SENSOR TOUCH S P E A K E R B U T T O N CHANNEL CORRECTION TlON REGULATOR S I D E P I N A M P...
  • Page 38 I rt KILLER A M P A M P K I L L E R P U L S E A M P A M P A M P P E D E S T A L B R I G H T E S S A M P 5 th V I D E O A M P...
  • Page 39 Tuner Figure 32. Tuner Schematic SAFETY NOTE: BOTTOM VIEW AC OUTLET BEFORE REPLACING r ‘YTrc" PARTS SINKS S H O U L D B E R E G A R D E D A S P O - TENT/AL SHOCK HAZARDS WHEN THE CHASSIS IS OPERATING.

  • Page 41: Parts List

    PARTS LIST _ _ _ _ _-- __-_ - - - - - - It is recommanded to use genuine factory SHARP replacement parts to assure fine performance. “How to order Replacement Parts” To have your order filled promptly and correctly, please furnish the following information-s.
  • Page 42 REF. NO. DESCRIPTION DESCRIPTION PART NO. PART NO. REF. NO. Diode, Protector 1 s1555 Diode, Temperature Compensation Diode, Damper PAL-Switch Diode, Side-pin. Variable capacitance Diode, Side-pin. 1 S2208 Diode Rectifier 19OV Variable Capacitance Diode, Rectification 1 S2208 Diode, Clamping Diode Diode, Protector Variable Capacitance 1 S2208...
  • Page 43 ‘REF. NO. PART NO. DESCRIPTION REF. NO. PART NO. DESCRIPTION Choke 18yH Filter 15pH Phase Shift Peaking 8.21.rH Filter 27pH Side Pincushion Phase Choke 2.21H Choke 2.2pH Side Pincushion Amp. Choke 2.2pH Choke 68ccH Focus 15M ohm Choke 68pH Choke 68crH R-Bias 5K ohm Transformers G-Bias 5K ohm...
  • Page 44 C e m e n t 2.2K o h m 5W 10% Oxide Metal Coating Front Cabinet Back Cabinet Metal Coating LED-Cover Door Oxide Metal Coating Badge “SHARP” Cement 10 ohm IOW 10% H BDG D301 GCESA Oxide Metal Coating Indicated Metal Panel Oxide Metal Coating Knob, On-Off-Vol.
  • Page 45 REF. NO. PART NO. DESCRIPTION Touch Button Hinge AC Cord Impedance Converter Fuse 2AT Fuse 2AT Fuse 1.6A Fuse 1 AT Antenna Terminal Socket, Picture Tube Spark Gap Spark Gap Spark Gap Service Switch Door Switch High Voltage Rectifier Unit RR ET-OO29C EZZ Speaker Tuner...
  • Page 46 S H A R P...