Changhong Electric PF2939 Service Manual
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Changhong Electric PF2939 Service Manual

Changhong Electric PF2939 Service Manual

Chassis no. ch-16cd
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FILE NO. SM-CTV-G-005
COLOR TELEVISION
SERVICE MANUAL
MODEL NO. PF2939
CHASSIS NO. CH-16CD
Please read this manual carefully before service.

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Summary of Contents for Changhong Electric PF2939

  • Page 1 FILE NO. SM-CTV-G-005 COLOR TELEVISION SERVICE MANUAL MODEL NO. PF2939 CHASSIS NO. CH-16CD Please read this manual carefully before service.

  • Page 2: Table Of Contents

    SERVICE MANUAL TABLE OF CONTENTS SAFETY INSTRUCTIONS AND MAINTENANCE ........1 X-Ray Radiation Precaution ....................1 Safety Precaution ........................1 Product Safety Notice ......................2 Maintenance......................KEY ICS AND ASSEMBLIES ..................4 SYSTEM BLOCK DIAGRAMS ................5 Structure Block Diagram .....................5 Block Diagram for Supply Voltage System ..............6 SERVICE DATA ........................7...

  • Page 3: Safety Instructions And Maintenance

    SERVICE MANUAL SAFETY INSTRUCTIONS AND MAINTENANCE “ WARNING: BEFORE SERVICING THIS CHASSIS, READ THE X-RAY RADIATION ” “ ” “ ” PRECAUTION SAFETY PRECAUTION PRODUCT SAFETY NOTICE INSTRUCTIONS BELOW. X-RAY RADIATION PRECAUTION 1. The EHT must be checked every time the TV is serviced to ensure that the CRT does not emit X-ray radiation as result of excessive EHT voltage.

  • Page 4: Product Safety Notice

    SERVICE MANUAL 4. When replacing ICs, use specific tools or a static-proof electric iron with small power (below 35W). 5. Do not use a magnetized screwdriver when tightening or loosing the deflection yoke assembly to avoid electronic gun magnetized and decrement in convergence of the CRT. 6.

  • Page 5: Maintenance

    SERVICE MANUAL Safety Symbol Description The lightning symbol in the triangle tells you that the voltage inside this product may be strong enough to cause an electric shock. Extreme caution should be exercised when working on the TV with the back removed. This is an international hazard symbol, telling you that the components identified by the symbol have special safety-related characteristics.

  • Page 6: Key Ics And Assemblies

    SERVICE MANUAL KEY ICS AND ASSEMBLIES Table 1 Key ICs and Assemblies Serial Position Model No. Function Description N201 OM8373PS(CH05T1632) N202 AT24C16 EEPROM N301 TA1343N Audio processor N401 TDA8350 Vertical output circuit N361 TDA8944J Sound power amplifier N901 TA1219AN TV/AV switch circuit IC801 STR-G8656 Power supply circuit...

  • Page 7: System Block Diagrams

    SERVICE MANUAL SYSTEM BLOCK DIAGRAMS Structure Block Diagram AV Terminals in AV Switch L in Audio Processor Audio Amplifier TA1218/1219 R in TA1343N (N301) TDA8944J (N361) (N901) TV-V Monitor Out CRT Drive 42 43 Tuner IF Pre-Amplifier UOC 　 A101 + SAWF 　　　ＯＭ８３７３ＰＳ...

  • Page 8: Block Diagram For Supply Voltage System

    SERVICE MANUAL Block Diagram for Supply Voltage System...

  • Page 9: Service Data

    SERVICE MANUAL SERVICE DATA Technical Data of Key ICs OM8373PS (N201) ratio), black stretching and Dynamic Skin 1. General Description Tone Control The various versions of the OM8373 PS/ N3/A • Integrated chroma band-pass filter with series combine the functions of a video switchable centre frequency processor together with a μ-Controller and •...
  • Page 11 SERVICE MANUAL 4.Block Diagram...
  • Page 12 SERVICE MANUAL 5.Refer to Table 2 about Functions and Service Data of the IC’s Each Pin.
  • Page 13 SERVICE MANUAL AT24C16 (N202) EEPROM 1. Features ・ Low Voltage and Standard Voltage Operation Devices Available 5.0 (V = 4.5V to 5.5V) ・ 8-Pin and 14-Pin JEDEC SOIC and 8-Pin PDIP 2.7 (V = 2.7V to 5.5V) Packages 2.Description 2.5 (V = 2.5V to 5.5V) 1.8 (V = 1.8V to 5.5V)
  • Page 14 SERVICE MANUAL 3.Block Diagram Fig.6 4.Refer to Table 3 about Functions and Data of the IC’s Pins.
  • Page 15 SERVICE MANUAL TA1343N TV Sound Processor TA1343N is a sound processor controlled by I2C bus. It incorporates the following: 2-channel input, 3-channel output signal processing circuit, phase shift circuit for surround, and LPF for woofer channel. ALS (Automatic Level Suppresser) circuit which prevents distort Weight : 1.22g (Typ.) the signal in large signal condition for woofer...
  • Page 16 SERVICE MANUAL 3) Terminal Function Table 14 PIN No. NAME FUNCTION DC offset canceling filter for bass boost. Offset canceling filter Connect a capacitor (10uF) between this terminal and GND. φ4 Terminals for capacitors of the phase shift blocks. φ3 Value of phase shift each block is [deg.]=-2tan-1(2 fCR).
  • Page 17 SERVICE MANUAL TDA8350 (N401) DC-coupled Vertical Deflection and East-West Output Circuit ・ High EMC immunity due to common mode 1. Features inputs ・ Few external components ・ Temperature (thermal) protection ・ Highly efficient fully DC-coupled vertical output ・ East-West output stage with one single bridge circuit conversion resistor.
  • Page 18 SERVICE MANUAL TDA8944J (N361) Audio Power Amplifier 1. General Description The TDA8944J is a dual-channel audio power 2. Features amplifier with an output power of ・ Few external components 2 × 7 W at an 8 Ω load and a 12 V supply. The ・...
  • Page 19 SERVICE MANUAL TA1219AN (N901) Audio/Video Switching IC for TVs The TA1219AN is an audio/video switching IC for TV Sets. Conforming to I C bus standards, it allows you to perform various switching operations through the bus lines by using a microcomputer. Furthermore, since the presence of a signal on its sync signal output pin can be determined by a microcomputer , it is possible to check each input/output channel (self-diagnosis).
  • Page 20 SERVICE MANUAL 2. Block Diagram Fig.11 3. Refer to Table 7 about Functions and Service Data of TA1219AN’s Pins.
  • Page 21 SERVICE MANUAL STR-G8656 (IC801) The Series STR-G 86656/5653/F6654 is specifically designed to satisfy the requirements for increased integration and reliability in off-line quasi-resonant flyback converters. The series incorporates a high-precise error amplifying control and drive circuit with discrete avalanche-rated power MOSFET, featuring fewer external components, small-size and standard power supply.
  • Page 22 SERVICE MANUAL 　 3. Pin Configuration and Functions Fig.14 3.1) Pin function for STR-G5653/8656 Function Description Pin No. Symbol MOSFET drain MOSFET source Ground Supply voltage input for control circuit OCP/FB Over-current protection detection signal/ voltage-limiting signal input 3.2) Pin function for STR-F6654 Pin No.

  • Page 23: Service Data Of Key Ics

    SERVICE MANUAL SERVICE DATA OF KEY ICs Table 2 Functions and Service Data of TDA9373 (N201)’s Pins Digital Multimeter Positive Negative Functions Description Reference Resistance Resistance Voltage (V) (20KΩ) (20KΩ) 0.17 ∞ 2.59 Port 1.3 or Counter/Timer 1 input Port 1.6 or I C-bus clock line 4.3~4.6 5.45...
  • Page 24 SERVICE MANUAL Ground 2 for TV processor 4.17 2.64 Narrow band PLL filter or AGC sound IF 2.32 Automatic Volume Levelling / sound IF input / 3.68 2.73 subcarrier reference output / audio 0.034 deemphasis Horizontal output 3.14 6.26 2.64 4.98 2.78 Flyback input/sandcastle output...
  • Page 25 SERVICE MANUAL Table 3 Functions and Service Data of AT24C16 (N202)’s Pins Digital Multimeter Functions Description Positive Resistance Negative Resistance Reference Voltage (20KΩ) (20KΩ) Address input Address input Address input Common ground 4.3~4.6 Serial data 5.75 1.91 4.3~4.6 Serial clock input 5.75 2.23 Write protect...
  • Page 26 SERVICE MANUAL Table 5 Functions and Service Data of TDA8350Q-N6 (N401)’s Pins Digital Multimeter Positive Negative Pin No. Function Description Reference Resistance Resistance Voltage (V) (20KΩ) (20KΩ) Vertical drive input (positive) 2.33 5.16 2.70 Vertical drive input (negative) 2.25 5.16 2.70 Feedback input 8.03...
  • Page 27 SERVICE MANUAL Table 7 Functions and Service Data of TA1219AN (N901)’s Pins Digital Multimeter Function Description Positive Negative Reference Ω Ω Voltage(V) Resistance(20K Resistance(20 K Get Select 6.54 2.69 Get Select 3.69 4.32 2.65 Lin TV 5.12 3.89 2.79 Rin TV 5.11 3.95 2.79...
  • Page 28 SERVICE MANUAL Table 8 Functions and Service Data of STR-G8656 (IC801)’s Pins Digital Multimeter Functions Positive Negative Description AC Power:110v 50/60Hz AC Power:220v 50/60Hz Resistance Resistance Reference Voltage (V) Reference Voltage (V) (20KΩ) (20KΩ) ∞ 0.062 0.037 32.23 ∞ 32.19 1.83 DCP/FB 1.75...

  • Page 29: Waveforms Of Key Points

    SERVICE MANUAL Waveforms of Key Points N201’s Pin2 N201’s Pin3...
  • Page 30 SERVICE MANUAL N201’s Pin22 N201’s Pin32...
  • Page 31 SERVICE MANUAL N201’s Pin33 N201’s Pin34...
  • Page 32 SERVICE MANUAL N201’s Pin38 N201’s Pin42...
  • Page 33 SERVICE MANUAL N201’s Pin43 N201’s Pin59...
  • Page 34 SERVICE MANUAL N401’s Pin5 N401’s Pin9...
  • Page 35 SERVICE MANUAL N401’s Pin11...

  • Page 36: Adjustments

    SERVICE MANUAL ADJUSTMENTS Set-up Adjustments ●The following adjustments should be made when a complete realignment is required or a new CRT is installed. Perform the adjustments in order as follows. 1. Color purity 2. Convergence 3. White Balance Note： The purity/convergence magnet assembly and rubber wedges need mechanical positioning. Refer to Fig.
  • Page 37 SERVICE MANUAL Fig. 16 2. Convergence Adjustment Note: Before attempting any convergence adjustment, the TV should be operated for at least 15 minutes. ●Center convergence adjustment 1) Receive the crosshatch test pattern. 2) Set the brightness and contrast properly. 3) Adjust two tabs of the 4-pole magnet to change the angle between them and red and blue vertical lines are superimposed on the center area of the screen.

  • Page 38: Circuit Adjustments

    SERVICE MANUAL Tighten the screw firmly to fix the yoke and check if the yoke is fixed. 9) Stick three adhesive tapes on wedges as shown in Fig. 15. 4-pole Magnet Movement 6-pole Magnet Movement Center Convergence by Convergence Magnets Incline the Yoke Up (or Down) Incline the Yoke Right (or Left) Circumference Convergence by DEF Yoke...
  • Page 39 SERVICE MANUAL A degaussing coil is mounted around the CRT so that external degaussing after moving the TV is generally unnecessary, providing it is properly degaussed upon installation. The degaussing coil operates in about 1 second after power on. If the set is moved or faced to a different direction, the power switch must be switched off for at least 30 minutes in order that the automatic degaussing circuit operates properly.

  • Page 40: Service Mode And Bus Data

    SERVICE MANUAL Service Mode and Bus Data 1. How to Enter the Service Mode with the Remote Control 1) Decrease volume to 0. 2) Press and hold down the MUTE button on the remote control for 2 second then press MENU button on the TV. 3) Adjust the TV with the MENU SELECT buttons on the remote control.
  • Page 41 SERVICE MANUAL Set to optimum Red gun drive voltage Set to optimum Green gun drive voltage Set to optimum Blue gun drive voltage YDFP YC delay Set to optimum Video automatic gain control UOC volume control 9860 IFFS Picture intermediate frequency HDOL Cathode drive voltage AGC linearity...
  • Page 42 SERVICE MANUAL WFRA Woofer volume linearity WFRB Woofer volume linearity WFRC Woofer volume linearity WFRD Woofer volume linearity SAGC Sound automatic gain control VXZM VAON VXON VSON VSHO PDEL CON1 Contrast Max CON2 Contrast Min BRI1 Set to optimum Brightness Max. BRI2 Set to optimum Brightness Min.
  • Page 43 SERVICE MANUAL Super woofer volume control: 1→Yes, 0→No OP_WOOFER_VOL OP_DIRECT_TIMER OP_DVD_SVM o:No, 1:Yes OP_LED_ONOFF OP_ENGLISH English: 1→Yes, 0→No Portuguese: 1→Yes, 0→No OP_PORTUGUESE OP_FRENCH French: 1→Yes, 0→No OP_SPANISH Spanish: 1→Yes, 0→No OP_VM Velocity modulation: 1→Yes, 0→No UOC_SVM TDA9379 SVM: 1. Yes, 0.No OP_AVC AVC: 1→Yes,...
  • Page 44 SERVICE MANUAL Standby mode after power-on: 1 Standby, OP_STANDBY 0 The same as last power-off mode Lock used identifying OP_LOCK detection: 1:Yes, 0:No Lock handle: 1:TXT12 | Lock; OP_IDENT_MODE 0:TXT12 & Lock OP_COLOUR_MATRIX Matrix: 1:USA; 0 :Japan OP_FORF According to Datasheet OP_FORS According to Datasheet OP_CHILD_LOCK...

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