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SERVICE MANUAL
PT 2 CHASSIS




Modification reserved
                                                             PT-2 Chassis Service Manual




CONTENTS
                                                                                              PAGE
   Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
   Standard and optimal features . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

   Recommendation for service repairs . . . . . . . . . . . . . . . . . . .6
   Scart pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
   Component description . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
   Adjustment procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
   Usage of the service submenu . . . . . . . . . . . . . . . . . . . . . . .10
   Block diagrams (mono and stereo) . . . . . . . . . . . . . . . . . . .12
   Fault tracing diagram-power supply . . . . . . . . . . . . . . . . . . .14
   Trouble shooting guide for main PCB . . . . . . . . . . . . . . . . . .15
   Descriptions of the parts . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
       1- Switch mode power supply stage . . . . . . . . . . . . . . . . . . .16
       2- Micro controller stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
       3- Analog operation part . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
       4- Vertical deflection circuit . . . . . . . . . . . . . . . . . . . . . . . . . . .17
       5- Horizontal drive circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
       6- Sound output stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
       7- CRT stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

   Descriptions of the integrated circuits . . . . . . . . . . . . . . . . .18
       - TDA4605 (Power supply) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
       - SDA5250 (Micro controller - teletext) . . . . . . . . . . . . . . . . . . . .21
       - 27C1001 (128Kx8 UV eprom) . . . . . . . . . . . . . . . . . . . . . . . . . .24
       - 24C08 (8K (1x8) Eeprom) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
       - HEF 4053 (Triple 2-Channel anoloque multiplexer/demultiplexer 26
       - TDA8361/TDA8362 (Anolog operation) . . . . . . . . . . . . . . . . . . .27
       - TDA9821 (Dual channel - sound processor) . . . . . . . . . . . . . . .31
       - TDA9830 (AM sound demodulator) . . . . . . . . . . . . . . . . . . . . .33
       - TDA9840 (Stereo / dual sound processor) . . . . . . . . . . . . . . . . .34
       - TDA9860 (Stereo sound processor) . . . . . . . . . . . . . . . . . . . . . .36




                                                                                                       3
PT-2 Chassis Service Manual




                              - TBA120U (Fm demod and Af amp.) . . . . . . . . . . . . . . . . . . . .38
                              - TDA3845 (Fm Am sound) . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
                              - TDA4470B (Multistandard video/sound IF signal processing) . . . 41
                              - TDA4665 (Baseband delay line) . . . . . . . . . . . . . . . . . . . . . . .45
                              - TDA8395 (Secam decoder) . . . . . . . . . . . . . . . . . . . . . . . . . .46
                              - SAA7283 (Terre strial digital sound decoder) . . . . . . . . . . . . . .47
                              - TDA7056A (Audio amp. for mono sets) . . . . . . . . . . . . . . . . . .52
                              - TDA7057AQ (`Audio amp. for stereo sets) . . . . . . . . . . . . . . . .53
                              - TDA3653B (Vertical deflection output) . . . . . . . . . . . . . . . . . .54
                              - TDA6103Q (Video output amplifier) . . . . . . . . . . . . . . . . . . . .55
                              - BUH515D (High voltage NPN fastswitvhing transistor) . . . . . . . .56
                              - BUZ90 (Power field effect transistor . . . . . . . . . . . . . . . . . . . . .59

                      RC hand unit and circuit diagram . . . . . . . . . . . . . . . . . . . .61
                      RC Transmitter PCB circuit diagram . . . . . . . . . . . . . . . . . . .62
                      Oscilloscope shapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
                      OPTIONAL BOARDS
                          - Nicam board circuit diagram . . . . . . . . . . . . . . . . . .64
                          - German stereo board circuit diagram . . . . . . . . . . .66
                          - Nicam L board circuit diagram . . . . . . . . . . . . . . . . .68
                          - A2 + Nicam L board circuit diagram . . . . . . . . . . . . .70
                          - Double scart board circuit diagram . . . . . . . . . . . . .72
                          - Main board circuit diagram . . . . . . . . . . . . . . . . . . . .74
                      Exploded wiews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76
                      Chassis replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78
                      The part list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79




4
                                                                                                                                                        PT-2 Chassis Service Manual




TECHNICAL DATA

   STANDARD FEATURES

                                                                Tube                           900 Max. 14", 20", 21" 4/3 CPT
                                                                Color System                   PAL B/G
                                                                Tuning System                  Voltage Synthesis Tuner
                                                                Power Source                   AC 165 V ~ 265 V
                                                                Power Consumption              60 W mono, 70 W Stereo
                                                                In Stand-By Mode               Less Than 5 Watts
                                                                Channel Coverage               VHF (2-4/5-12), UHF (21-69), CATV (S1-S41)
                                                                Number of Programs             99+1 AV (2 AV optional)
                                                                Audio Output                   2x8 ohm stereo
                                                                                               2x8 ohm mono
                                                                Antenna Input                  75 ohm IEC




   STANDARD FEATURES                                                                                        OPTIONAL FEATURES

                                    m                             ATS                                                        m               Headphone
                                            m                     Parental Lock                              m                               PAL I, PAL SECAM BG, PAL/SECAM
    m                                                             Cable TV (Hyper Band)                                                      BG+DK
                                                    m             Fine Tuning                                                                PAL/SECAM BG+LL', NTSC 4.43
                                                                                                                                             playback
        m                                                         Simple Text / Fast Text / Top Text
                                                                                                                     m                       German Stereo
            m                                                     Auto Shut Off
                                                        m         Normalization                                                  m           Nicam BG, Nicam L, Nicam I
                                                                                                                                         m   German Stereo + Nicam L
                        m                                         OSD with user friendly menu
                m                                                 Sleep Timer                                            m                   Double Scart
                                                                                                                                     m       Bass, Treble, Balance and Sound
                                        m                         Real Time Clock From Teletext
                                                                                                                                             Effect
                                                                  Sync
                                                                                                                 m                           German Stereo + NICAM BG/I
                                                            m     Hotel Mode
                    m                                             Storing Program name with 4
                                                                  character
                                m                                 Top Ten List
                                                m                 Menu Commands in 9 Language
                            m                                     Euro AV




                                                                                                                                                                                  5
PT-2 Chassis Service Manual




RECOMMENDATION FOR SERVICE REPAIRS
    1- Use only original spare parts. Only use compo-              outside the cabinet or with back cover removed
       nents with the same specifications for replace-             involve a shock hazard from the receiver.
       ment.                                                       Servicing should not be attempted by anyone
    2- Original fuse value only should be used.                    who is not thoroughly familiar with the precauti-
    3- Main leads and connecting leads should be                   ons necessary when working on high voltage
       checked for external damage before connecti-                equipment.
       on.                                                         Perfectly discharge the high potential of the pic-
       Check the insulation.                                       ture tube before handling the tube. The picture
    4- Parts contributing to the safety of the product             tube is highly evacuated and if broken.
       must not be damaged or obviously unsuitable.                Glass fragments will be violently expelled.
       This is valid especially for insulators and insulating      Always discharge the picture tube anode to the
       parts.                                                      receiver chassis to keep of the shock hazard be-
    5- Thermally loaded solder pads are to be sucked               fore removing the anode cap.
       off and re-soldered.                                     8- Keep wire away from the high voltage or high
    6- Ensure that the ventilation slots are not obstruc-          temperature components.
       ted.                                                     9- When replacing a wattage resistor in circuit bo-
    7- Potentials as high as 25 KV are present when this           ard, keep the resistor 10 mm away from circuit
       receiver is operating. Operation of the receiver            board.




HANDLING OF MOS
CHIP COMPONENTS
    MOS circuit requires special attention with regard             until they are used. Most components must never
    to static charges. Static charges may occur with               be stored in styropor materials or plastic magazi-
    any highly insulating plastics and can be transfer-            nes.
    red to persons wearing clothes and shoes made of            2- Persons have to rid themselves of electrostatic
    synthetic materials. Protective circuits on the inputs         charges by touching MOS components.
    and outputs of mos circuits give protection to a li-
                                                                3- Hold the component by the body touching the
    mited extend only due to time of reaction.
                                                                   terminals.
    Please observe the following instructions to protect        4- Use only grounded instruments for testing and
    the components against damage from static char-                processing purposes.
    ges.                                                        5- Remove or connect MOS ICs when operating
    1- Keep mos components in conductive package                   voltage is disconnected.




X-RAY RADIATION
PRECAUTION
    1- Excessive high voltage can be produce potenti-              the reading of the high voltage be recorded as
       ally hazardous X-RAY radiation. To avoid such ha-           a part of the service record. It is important to use
       zard, the high voltage must not be above the                an accurate and reliable high voltage meter.
       specified limit. The nominal value of the high vol-      2- The primary source of X-RAY radiation in this TV
       tage of this receiver is 25KV at zero beam current          receiver is the picture tube. For continued X-RAY
       (minimum brightness) under 220V AC power sour-              radiation protection, the replacement tube must
       ce. The high voltage must not under any cir-                be exactly the same type tube as specified in
       cumstance, exceed 30KV. It is recommended                   the part list.

6
                                                                       PT-2 Chassis Service Manual




SPECIFICATIONS OF THE CONNECTOR
(EURO SCART)
   I- Audio output 1. right channel 0.5 VRMS/<1k
   2- Audio input 1. right channel 0.5 VRMS (connected to No.6 on mono TV set.)
   3- Audio output 2. left channel 0.5 VRMS (connected toNo.1 on mono TV set.)
   4- GND (audio)
   5- GND
   6- Audio input 2. left channel 0.5 VRMS/>10k 
   7- RGB input, blue (B)
   8- AV status
   9- GND
  10- Reserved for clock signals (not connected)
  11- RGB input, green (G)
  12- Reserved for remote control (not connected)
  13- GND
  14- GND switch signal RGB
  15- RGB input, red (R)
  16- RGB Switching input (1V dc)
  17- GND (video)
  18- GND19- Video output 1 Vpp/75 ohm
  20- Video input 1 Vpp/75 ohm
  21- Shield



                  1       3       5       7    9   11 13 15 17 19 21




                      2       4       6       8 10 12 14 16 18 20




                                                                                                 7
PT-2 Chassis Service Manual




COMPONENT DESCRIPTIONS


                              POWER CORD




                              SAW FILTER




                              IR SENSOR




                              VOLTAGE REGULATOR


                              ON/OFF SWITCH



                              LINE FILTER


                              PTC

                              NPN TRANSISTOR

                              PNP TRANSISTOR

                              CERAMIC FILTER
                              COIL
                              LINEARITY COIL

                              FUSIBLE RESISTOR
                              IW METAL OXIDE RESISTOR
                              1/2W METAL OXIDE RESISTOR
                              1/4 OR 1/6W CARBON FILM RESISTOR
                              CERAMIC CAPACITOR /POLYESTER CAPACITOR
                              ELECTROLITIC CAPACITOR
                              DIODE
                              ZENER DIODE
                              SWITCH JUMPER
                              NET (INPUT)
                              NET (OUTPUT)
                              TACT SWITCH
8
                                                                                                                                                                              PT-2 Chassis Service Manual




ADJUSTMENT PROCEDURE
  1- System Voltage (+B) Adjustment :
                                               m                                                               Before switching on TV, all potentiometers should be adjusted at medium level. Then TV is
                                                                                                               switched on;
                                                                                                           m   Adjust all of the analog parameters to minimum with RC
                                                               m                                               Adjust P1 trimpot until find +115 V on the cathode of D2 diode

  2- AFT Adjustment:
                   m                                                                                           Place a balloon coil (300 Ohm dc resistance ) parallel to L104
                                                                   m                                           Apply 80 dB uV 38.9 MHz (39.5 MHz for I ) signal via balloon coil
               m                                                                                               Connect a voltmeter to aft pin (pin 9) of IC301
                                                                           m                                   Adjust T101 coil until the voltage of this pin being 2.5 V dc

  3- Adjustment of G2:
                           m                                                                                   Apply Philips Test pattern
                                                                                   m                           Adjust all of the analog parameters to minimum with RC
                               m                                                                               Adjust G2 trimpot until seeing two bars on gray scale

  4- Horizontal and Vertical Adjustment:
                                                                                                           m   Apply Philips Test pattern signal
                                                                                           m                   Center the picture horizontally while picture shifting to right and left with P101,
                                           m                                                                   Make vertical amplitude adjustment with P602 until seeing top and lower lines of picture will
                                                                                                               be seen
                                                                                               m               Center the picture with P601

  5- AGC Adjustment:
   m                                                                                                           Apply Philips Test Pattern whose amplitude is 60 dB uV to the rf input
                                                   m                                                           Adjust P102 until find a picture without snowy

  6- Focus Adjustment:
                                   m                                                                           Apply Cross-Hatch Pattern signal
                                                                                                       m       Find the optimum concentration point between H and V intersection in the middle of screen.

  7- White Balance Adjustment :
                                                           m                                                   Apply Philips Test Pattern signal
                                                                                       m                       Adjust all of the trimpots on CRT board to medium level
                                                                               m                               Adjust color, contrast, brightness to minimum by RC
           m                                                                                                   Adjust G2
                                                                                                   m           Apply white pattern, settle in the probe of color analyzer to screen
                                                                       m                                       Increase brightness until geting Y=10 nits
                                                       m                                                       Adjust x=270 - 276 nits y=270 - 276 nits via "VR201, VR203, VR205"
                       m                                                                                       Increase brightness and contrast until Y=90 - 100 nits
                                       m                                                                       Adjust x, y to same values via "VR202 and VR204"
       m                                                                                                       Check white balance at high and low contrast level. Again make adjustment if it's necessary.




                                                                                                                                                                                                               9
PT-2 Chassis Service Manual




USAGE OF THE SERVICE SUBMENU

     SOME TRICKS FOR THE SOFTWARE
     If the customer does not remember the password for child lock you can solve this problem as the
     following:
     Step           1: Turn TV ON,
                    2: Push P+
                    3: Push P-
                    4: Push V+
                    5: Push V-
                    6: Push OK
     keys respectively. Now, the lock was opened.
     When you entered SERVICE line, the TV will ask a password to you:
     The password is "089"


                      PARENTAL LOCK
                      TV-PROGRAMME CHART
                      AUTOMATIC PROGRAMMING
                      AUDIO/VIDEO INPUTS
                      SPECIAL FUNCTIONS
                      SERVICE



                      Ok Call up TV TV Picture



                     SERVICE

                      FOR AUTHORIZED DEALER ---


                      0-9 CODE       TV    TV-PICTURE

                      Enter "089"    code for password


      After entered "089" code, you will meet a menu as the following:

                      For authorized dealer


                      Factory set values
                      Production mode
                      Hotel mode                        off
                      Max. volume


                      Ok Call up TV TV Picture

10
                                                                          PT-2 Chassis Service Manual




Factory set values:

If you press OK key on the first line (Factory set values), then the EEPROM is being cleared and stored so-
me original parameters.
All stored programs will be cleared.


Production mode:

You will see the following menu:


                Production mode
                        Contrast
               1         White level
               2         Black level
               3         Fast programming
                P+, P-   Change prog. number


                                                       M Return




You can adjust white and black level pressing 1 and 2 keys respectively. If you switch off the TV in this sub
menu, during the next opening, the TV starts to run from this menu directly. You should leave from this sub
menu pressing M key.
Fast programming is used in the factory.



Hotel Mode:
If you press V+/- key on this line, you can make the hotel mode as on. Now, you can adjust the maximum
available volume for hotel room. You leave from this sub menu pressing TV button.

If the Hotel Mode is ON, you can not use the
        PARENTAL LOCK
        TV-PROGRAMME CHART,
        AUTOMATIC PROGRAMMING sub menus.




                                                                                                           11
PT-2 Chassis Service Manual




12
PT-2 Chassis Service Manual




                         13
PT-2 Chassis Service Manual




FAULT TRACING DIAGRAM-POWER SUPPLY

                                                                  Inportant Service Note :
                                      Switched mode power
                                  supply defective,+115 voltoge   Before changing a component in the
                                   is missing or level is wrong
                                                                  Primary Mains Stage it is imperative,
                                                                  that C5 is discharged by a resistor
                                                                  of approx. 100 K.

           D1,D2,D3,D4      YES            Fuse eg.
             C1,C2,C5                    F01 defective



                                                    NO

                                                                    ATTENTION!A short circuit transistor
                            NO                                      Q602 can be a result of a defective
               R1,Q1                     Voltage at drain
                                                                         D20, R20, or the cut-off
            short circuit                      Q1                             components
                                                                                 D5,R3

                                                 YES

                                           Voltage at
                            YES
                 R5                        IC630-(3)
                                             < 1V



                                                    NO


               R2,I2        YES         Start-up voltage
                                           IC630-(6)
                 D8                           < 8V



                                                    NO


                            YES
                                        Start-up voltage
              Q 602
                                          varies ca. 8V



                                                    NO

                                               I1


                                     Measure +115 V supply




                            NO               +115V
            P1,R9,ZD1                    adjustable with
                                               P1



                                                 YES
                                      Control range of
                                    switched-mode power
                                      supply 165-270V




14
                                                                    PT-2 Chassis Service Manual




TROUBLE SHOOTING GUIDE FOR MAIN PCB


         TROUBLE                                 CHECK POINTS
No color                      I 101, X 102, C 127, I 102, I101 pin 38
No vertical deflection        Check +K, I 601, I101 pin 42, I 101 pin 43
Vertical linearity            C 625, R 623
Vertical size                 C 626, R 624
Vertical shift                R 626, P 601
Horizontal linearity          L 601, C 608
Horizontal size               +B, C 607, L 602
Flue picture                  I 101 pin 25, ABL, FOCUS, HEATER, EHT
Dark picture                  I 101 pin 17, SCREEN, EHT, +M
Noise picture                 TU 01, AGC, IF, F 101
Vert./horizontal synchrony    X 102
Interference                  TU 01, IF, F 101
No sound                      Check I 101 pin 5 and pin 50, I 401 pin 3, pin 5, +G
Low sound                     I 101 pin 5, pin 50, I 401 pin 5, +G, R 403
Sound distortion              I 401, +G, R 403
Contrast                      I 301 pin 81, I 101 pin 25, ABL
Brightness                    I 301 pin 82, I 101 pin 17
Color saturation              I 301 pin 83, I 101 pin 26
Tuning                        I 301 pin 77, Q 301, +D,TU 01
Memory                        I 302, SDA, SCL
Band select                   I 301 pin 72, 74, 75, +K, TU 01, Q 302, 303, 304
No video-out on the SCART     Check TV-VID signals, Q 651
No video-in on the SCART      Check I 301 pin 76, I 101 pin 16 on AV mode, check the
                              video signals on AV mode SCART pin 20 and I 101 pin 101
No sound out on the SCART     I 101 pin 1, Q 653 , Q654
No sound in on the SCART      Check the audio signals on SCART pin 2/6 and I 101 pin 15
No remote control reception   Check signals on pin 3, IR 01 and I 301 pin 73




                                                                                             15
PT-2 Chassis Service Manual




DESCRIPTION OF THE PARTS
                                 1- SWITCH MODE POWER SUPPLY STAGE                                       ed to be added a base-band delay line
                                                                                                         (TDA4665) a tuner and output stages for au-
                                                 In order to supply the DC voltage required at
                                                                                                         dio, video and horizontal and vertical def-
                                                 various parts of the chassis, an SMPS transfor-
                                                                                                         lection. TDA8362 can handle signals with po-
                                                 mer controlled by the IC TDA 4605 and switc-
                                                                                                         sitive modulation and it supplies the signals
                                                 hing transistor 3N90 (BUZ90) in used. CI, T1, C2
                                                                                                         which are required for secam decoder
                                                 filter circuit prevents the network noises and
                                                                                                         TDA8395.
                                                 the effects of high frequency which produced
                                                 in TV set. After rectifying DC voltage is filtered    VIDEO AMPLIFIER The IF amplifier contains 3 AC-
                                                 by using C5. The start up voltage of TDA4605.           coupled control stages with a total gain
                                                 This square wave reaches QI passing through             control range of greater than 60 dB. The re-
                                                 R8. After that Q1 form and induction on T2,             ference carrier for the video demodulator is
                                                 which produces a voltage on pin 6. This volta-          obtained by means of passive regeneration
                                                 ge rectified by D6 is used as a supply voltage          of the picture carrier. The external reference
                                                 of IC 1. IC 1 does not operates SMPS by stop-           tuned circuit is the only remaining adjust-
                                                 ping pulses at pin 5, when the network is higher        ment of the IC. In the TDA8362 the polarity of
                                                 or lover than fixed limits. Pin 2 is control pin of     the demodulator can be switched so that
                                                 overload. This stage produces 115V for FBT, 12          the circuit is suitable for both positive and
                                                 V for audio part, 33 V for tuning circuit 5V, for       negative modulated signals. The AFC circuit
                                                 tuner and some ICs and 8V (for TDA8362) are             is driven with the same reference signal as
                                                 produce by the means of the regulators                  the video demodulator. To ensure that the
                                                 LM7805, LM317. This circuit operates between            video content does not disturb the AFC ope-
                                                 165 VAC and 265 Vac (50Hz).(In stereo TV set            ration a sample and hold circuit incorpora-
                                                 aditionally 7808)                                       ted; the capacitor for this function is internal.
                                                                                                         The AFC output voltages 6V. The AGC de-
                                                                                                         tector operates on levels, top sync for nega-
                                 2- MICRO CONTROLLER STAGE                                               tive modulated and top white for positive
                                                 Below items are controlled or generated by              modulated signal. The AGC detector time
                                                 means of this controllers.                              constant capacitor is connected externally.
     m                                           SDA 5250 are used as a controller and teletext        SOUND IF CIRCUIT
                                                 decoder on PT2 chassis.                               On mono models
                                     m           Voltage synthesis tuning.                               The sound band pass and trap filters have to
                         m                       On screen display                                       be connected externally. The filtered inter
                                         m       Control of two transmission standard.                   carrier signal is fed to a limetter circuit and is
                                                                                                         demodulated by means of PLL demodula-
                             m                   Controls of the simple text or fast text decoder.       tor. Type PLL circuit tunes it self automatically
                     m                           Full peri-TV (scart) switching on stereo models.        to the incoming signal, consequently, no ad-
                                 m                Controls of stereo decoder TDA9840 and                 justment is required.
                                                 TDA9821 as German Stereo Decoder.                       The volume is DC controlled. The composite
                 m                               SAA7283 as Nicam decoder.                               audio output signal has an amplitude of 700
                                             m   Sound processing (Bass, treble, balance).               mV RMS at a volume control setting of-6 dB.
                                                                                                         The emphasis capacitor has to be connec-
             m                                    Controls of the analog values of the picture           ted externally. The non-controlled audio sig-
                                                 (Brightness, Color, Contrast)                           nal can be obtained from pin 1 via a buffer
         m                                       SDA5250 hasn't got internal ROM, so 27C010 EP-          stage. The amplitude of this signal is 350 mV
                                                 ROM is used for external ROM.                           RMS.
                                                                                                         The TDA8362 external audio input signal must
                         3- ANALOG OPERATION PART WITH                                                   have an amplitude of 350mV RMS. The au-
                         TDA8362                                                                         dio/video switch is controlled via the chromi-
                                                 TDA8362 is a single-chip TV processor which             nance input pin.
                                                 contains nearly all small signal functions that       On stereo models
                                                 are required for color television receiver. For         On stereo models, the adjustable sound out-
                                                 a complete receiver the following circuit ne-           put pin (pin50) is used for mono sound. An


16
                                                                         PT-2 Chassis Service Manual



  external sound IF circuit TDA3845 is used for NI-       during normal operation.
  CAM B/G, I stereo systems. For NICAM L stereo
  system, TDA4470B sound IF IC is used so that ob-       5- HORIZONTAL DRIVE CIRCUIT
  tain AM sound and NICAM I sound carrier. On             The horizontal drive pulses obtained from pin 37
  German stereo system, TBA120U is used as FM             of the 8362 are connected to base of
  demodulator for second sound carrier.                   Q601(2SC1573) via R602. Q601 drives Q602
SYNCHRONIZATION CIRCUIT                                   (BUH515D) via the drive transformer T602. T601 is
 The sync is preceded by a voltage controlled             the EHT transformer. +B (115V) is switched by
 amplifier which adjust the sync pulse amplitude          Q602 and T601 generates both "EHT, FOCUS,
 to a fix level.                                          G2 voltages required for CPT "and" 170V, he-
 The sync pulses are then fed to the slicing stage        ated voltage and 26V vertical supply voltage".
 (separator) which operates at 50% of the ampli-          The anode beam current information from pin 7
 tude. The separated sync pulses are fed to the           of T601 is used for reducing contrast at too high
 first phase detector and to the coincidence              beam currents, in order to stabilize the voltages
 detector. The coincidence detector is used for           derived from power supply.
 transmitter identification and to detect whet-
 her the line oscillator is synchronized. When the       6- SOUND OUTPUT STAGE
 circuit is not synchronized, the voltage on the          On mono models, TDA7056A is used as sound
 peaking control pin (pin 14) is LOW so that this         output amplifier with DC volume control. Pin 50
 condition can be detected externally.                    of the TDA8362 is AC coupled to the input pin 3
 The IC TDA8362 contains a start up circuit for           of the TDA7056A via a RC filter. It is supplied by
 the horizontal oscillator. When this feature is re-      + 12V coming from a separate winding in the
 quired a current of 6.5 mA has to be supplied to         SMPS transformer. On stereo models, TDA705-
 pin 36.                                                  7AQ is used as sound amplifier. The sound level
COLOR DECODING                                            is controlled by sound processor TDA9860 via
                                                          12C bus on stereo boards. The outputs of
 TDA8362 contains PAL, SECAM and NTSC deco-               TDA9860 (pin 15 and pin 18) is connected to
 der (TDA8361 contains only PAL decoder) but it           TDA7057AQ via a divider circuit and two capa-
 can cooperate with the Secam add-on Secam                citors.
 decoder TDA8395. The communication betwe-
 en two IC's is achieved via pin 32. The TDA8362
 supplies the reference signal (4.43 MHz) for the        7- CRT STAGE
 calibration system of the TDA8395 identification         The TDA6103Q is used on CRT stage as video
 of the color standard is via the same connecti-          output amplifier. The TDA6103Q consist of Three
 on. When a SECAM signal is detected by the               monolithic video output amplifiers. Each ampli-
 TDA8395 the IC will draw a current of 150



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