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20vl44


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                          TOSHIBA


                         SERVICE MANUAL

                        COLOUR TELEVISION
                                                           20VL44




                                                               PRINTED IN UK.   2003 C




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                                                           CONTENTS         PAGES



                                      Safety instructions                     1

                                      Technical specifications                2

                                      Panel Specification                     3

                                      Chassis block diagram                   4

                                      Scaler block diagram                    5

                                      Block diagram of power supply           6

                                      Chassis overwiev                        7

                                      Service mode items and explanations    12

                                      Data sheet of important IC's           17

                                      Recommended Part List                  29

                                      Frequency list of channels             30




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                                    SAFETY PRECAUTIONS

                 GENERAL GUIDELINES


             1. Always use the manufacturer's replacement safety
                  components. The critical safety components marked          5        High temperature & high humidity
                  with     on the schematics diagrams should not be                   reduce the life-time.
                  by other substitutes. Other substitute may create the     LCD is not proper to be used at high temperature
                  electrical shock , fire or other hazards. Take            and high humidity. Please keep specified
                  attention to replace the spacers with the originals.      temperature and humidity condition.
                  Furthermore where a short circuit has occurred ,
                  replace those components that indicate evidence of          6-        Keep out of Corrosive Gas.
                  overheating.
                                                                            Corrosive gas effect the polarizer and the circuit
             2. After servicing , see that all the protective devices       chemically and cause defects accordingly.
                  such as insulation barriers, insulation papers, shields
                  and isolation R-C combinations are correctly                   7 -    Electrostatic discharge can make
                  installed.
                                                                                        Damage
             3. When the receiver is not being used for a long time
                  of period of time , unplug the power cord of the           There are electro-static sensitive components such
                  Adaptor from the AC outlet.                                as CMOS in LCD Module. Please earth human
                                                                             body when handle the LCD.In addition, please do
                                                                             not touch the interface connector pin with bare.
             Color TFT LCD Module is very sensitive
             both electrically and physically.Users,
             therefore, are requested to follow the                          8-        Do not operate for a long time under
             "Guidance of handling color TFT LCD                                       the same pattern
             Module"on the followings.
                                                                            Operating LCD for a long time under the same
                                                                            pattern can cause image persistence and can
                 1-     Be careful not to make scratch on the               damage it. Please follow following guidance.
                        polarizer.                                          1. Turn the power off when do not use.
             Surface of polarizer is soft and can be physically             2. Change the pattern periodically.
             damaged easily.
             Please do not touch, push or rub polarizer surface
             with materials over HB hardness.

                2-       Keep clean the surface.
             Please wear rubber glove when touch the surface of
             LCD screen. Please use soft and anti-static material
             as cleaner.

               3-        Keep out of water.
             Water on/in the LCD may cause electrical short or
             corrosion. Please wipe out dry or water carefully.

                4-       Prevent swift Temperature &
                         Humidity change.
             Instantaneous temperature and/or humidity change
             can make dew or ice which cause nonconformance
             such as malfunction.




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                                                      L5A TECHNICAL SPECIFICATION

                    Receiving System                                                               PAL B/G+I+D/K SECAM L/L'

                    Comb Filter                                                                         Adaptive 4H\2H
                    Scaling                                                                           Upto SXGA at 75Hz
                    Gamma Correction                                                                    8 to 10-bit LUT
                    Histogram Equalization                                                                   YES
                    Stereo Decoding
                                                                                                      German A2, Nicam
                    (German A2, Nicam, BTSC)
                    Stereo L, R In                                                                             3
                    Stereo L, R Out                                                                            3

                    Audio Output Power RMS in Max at 10% THD)                                        2x3W, 2x5W for 22"W

                                                                       Level (1.5, 2.5, Teleweb)          Teletext 1.5
                    Teletext                                           Type (Fast\Top\Simple)          Simple, Fast, Top
                                                                       Page Memory                        250p or 10p
                    WSS                                                                                        +
                    VPS\PDC                                                                                    +
                                                                       4:3                                     +
                                                                       16:9                                    +
                    Picture Formats
                                                                       Panorama                                +
                    (4:3, 16:9, 14:9, Panorama, LetterBox, Subtitle)
                                                                       Letterbox                               +
                                                                       Subtitle                                +
                    WSS (Wide Screen Signalling)                                                               +
                    ATS (Automatic Tuning System)                                                      Frequency Search
                    Manual Search                                                                    Channel Table Search
                    Number of Program Storage                                                                 100
                    No Ident Timer                                                                             +
                    Picture Freeze                                                                             +
                    Equalizer                                                                                  +
                    Zapping                                                                                    +
                    AVL (Automatic Volume Level)                                                               +
                    Sound Status Memory                                                                        +
                    Picture Status Memory                                                                      +
                    Swap                                                                                       +
                    Child Lock                                                                                 +
                    Program Lock                                                                               +
                    Picture Format Switching Thru Pin 8                                                        +
                    Auto RGB Detect Thru Pin 16                                                                +
                    PC Plug & Play (DDC\CI)                                                                    +
                                                                       Off Timer (Sleep Timer)                 +
                    Timer
                                                                       On Timer                                +
                    Picture Smart (User, Soft, Natural, Rich)                                                  +
                    Sound Smart (User, Music, Sports,
                                                                                                               +
                    Cinema, Speech)
                    Scart                                                                                      2
                    S-video (DIN)                                                                              1
                    AV In (3 RCA)                                                                              1
                    AV Out (3 RCA)                                                                       1 (ONLY L, R)
                    D-Sub 15                                                                                   1
                    Headphone                                                                                  1
                    CVBS In                                                                                    3
                    Y\C In                                                                                     1
                    RGB+FB -Video                                                                              1
                    RGB+HS, VS In -Graphics                                                                    1
                    CVBS Out                                                                                   2




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                                                                                         PANEL SPECIFICATION
                                     14"                 15"                 17"                 17W"                20"                 22W"                23W"

                                                         Samsung
                                                         Hannstar                                                    CMO
          Manufacturer               AUO                                Samsung                  Samsung                                 Samsung
                                                         CMO                                                         AUO
                                                         AUO      Sanyo

                                                         Double TTL\Single                                           Single TTL\Single
          Interface                  Single LVDS                             Dual LVDS           Single LVDS                             Single LVDS         Single LVDS
                                                         LVDS                                                        LVDS

                                                                                                                     SVGA (800x600)
          Resolution                 VGA (640x480)       XGA (1024x768)      SXGA (1280x1024)    WXGA (1280x768)                         WXGA (1280x720)     WXGA (1280x768)
                                                                                                                     VGA (640x480)

          Brightness (cd/m2)>        450                 250                 300                 400                 500                 450                 450


          Contrast>                  500                 300                 400                 400                 500                 500                 400

          Response Time
                                     25                  35                  25                  25                  16                  25                  25
          (Tr+Tf) msec <

          Viewing Angle R\L\H\L >    85/85/85/85         60/60/40/50         70\70\60\60         70/70 50/60         80\80\60\60         85/85 85/85         85/85 85/85


          Adaptor Input
                                     12V                 12V                 12V                 12V                 15V                 15V                 24V

          Power consumptions
                                     48W                 48W                 60W                 60W                 75W                 100W

          St-By Power Consumption    <3W                 <3W                 <3W                 <3W                 <3W                 <3W                 <3W



          Input Range                100-240V/50, 60Hz   100-240V/50, 60Hz   100-240V/50, 60Hz   100-240V/50, 60Hz   100-240V/50, 60Hz   100-240V/50, 60Hz   100-240V/50, 60Hz




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                                                           BLOCK DIAGRAM OF MAIN CHASSIS (L5A)

                                                             SVHS-Y/C           SC1-RGB


                                                                                                    YUV
                                         CVBS-IF                  YUV
                                                                     Video Decoder                                Scaler           PANEL
                    Tuner IF
                                                                      VPC 3230D                                   Stage
                                                                  HS/VS
                                                                                                    HS/VS
                                                                                                            RGB            HS/VS
                                                        HS/VS      RGB           FB      CVBS

                                                                                                                  VGA-IN           EEPROM
                                                                                                                                    24LC02
                                         EEPROM                     Teletext Decoder
                                          24LC16                       SDA 5550




                                                            K6T1008V2E                 M29W040
                                                               SRAM                      Flash
                                                             (Optional)                 Memory

                                                                                                             TDA1571
                                                                                                L
                                                                                                              Stereo
                                                                  R                             R            Amplifier
                                                                  MSP3410G
                                                                AUDIO DECODER
                                                                   L                            L             TDA1308
                                                                  R                             R            Headphone
                                                                                                              Amplifier
                      SIF/AM-mono
                                              Scart 1              Scart 2              SVHS/FAV




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                                                                 BLOCK DIAGRAM OF SCALER


                               BAC LIGHT UNIT          Panel_En Standby   Mute        Reset
                             S508 (LVDS) S500(TTL)

                         BR1_ADJ             BLK_EN


                HS/VS

                RGB                                                                                        LVDS
                                                GM 5221 U500                                           CONNECTOR
                                                    LCD                                               (20 OR 30 PINS)
                VGA_RGB
                                                                                                        (S503,S502)
                                                                                                                        P
                VGA HS/VS
                                                CONTROLLER                                                              A
                                                                                                                        N
                                                                                               S506
                                                                                              CONN.     DAUGHTER        E
                                                                                                          BOARD         L
                                                                                                         FOR TTL
                                                                                                       INTERFACES

                               U501
                             PARALEL                  U503                KEYBOARD
                              FLASH               SERIAL FLASH            CON. S509
                             MEMORY                 MEMORY
                             M29W040B               M25P40
                            (OPTIONAL)
                                                                  U502
                                         S505
                                                                 EEPROM
                                      PROGRAMING
                                                                  24C16
                                         CON




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                                     L5A POWER SUPPLY BLOCK DIAGRAM




                                                                                                           3.3V-STBY
                          S600                                                                   LM1117
                                            V-INV                                                 3.3V
             DC Jack                                           +15V-STBY
                                            F600      LM2576    15V,12V    LM2576    +5V-STBY
                                                       U600                 U607                 LM1117    1.8V-STBY
                                     Fuse                                                         1.8V
              S602                   5A                                                           U605

                                            F601
                                                    V-INV
                                                     V-INV
                                                                            78L08       +8V
                                                                            U606                                                                       2.5V
                                                                                                                                          LM117-3.3V
                                                                                                                                    +5V     U604       3.3V
           INPUT:      12V FOR 14,15,17 INCH                                                                5V-STBY       U602
                       15V FOR 20, 22 INCH                                               + 12V                         SDI9933ADY
                                                                             78L12
                       24V FOR 23 INCH                                                                                                    Panel
                                                                             U608
                                                                                                          +12V                            Power
                        ONLY FOR 23 "

                         ONLY FOR 20, 22, 23 "                                                                   PNL-EN Power STBY
                                                                                                 +8V
                                                                                         78L08
                                                                                         U606




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                       L5-A Low-to-Mid End LCD-TV BOARD OVERVIEW
                      L5-A Low-to-Mid End LCD TV board incorporates the LCD Controller gm2221, to create a
                      high quality, stand-alone LCD-based TV system for consumer applications. Figure 1
                      illustrates the Block diagram of the board.

                      This board supposed to have two versions:
                         1. Low-End (to drive 14''-15'' 4:3 panels)
                         2. Mid-End (to drive 17''-20'' 4:3 and 17''-22''-23'' 16:9 panels)


                                        LOW TO MID END LCD TV WITH GM2221

                                                        Graphics     RGB, HS, VS
                                                   Upto SXGA at 75Hz                                              FLASH
                                                     UXGA at 60Hz                              GM2221
                                               QSS                                                                NVRAM                15",
                                                               SDA,SCL                                                                 17",
                                                                        EDID
                                  Multimedia                            VGA                   ADC+PLL                                  20''
                                    Tuner      CVBS                                                                1p, 2p\clk          4:3
                                                                                                ITU 656              LVDS
                                                            Chroma                           De-interlace
                                                            Decoder                             Scaling                                17''
                                   EXT. CVBS, S-video                             ITU 656                           24-bit TTL
                                                           VPC 3230D                           MCU X86                                 22''
                                                                                                                   HS, VS, DE
                                                                                   8-bit    OSD(4bit\pixel)                            16:9
                                        Scart RGB, FB                                                           Upto SXGA at 75Hz
                                                                                              2 LVDS Tx                                TFT
                                                                                                                                       LCD

                             3.3V 2.5V 1.8V
                        5V
                                                                       Selected
                                                        RGB, FB
                                                        Teletext



                                                                        Video




                                                                                                        QSS
                             8V
                                                                                                      Ext L/R       Audio
                                                                                                                   Decoder
                          Step Down                                                                               MSP 3410G
                          & Lineer
                          Regulators                          Teletext            FLASH               HP                        Main
                                                           Decoder +MCU                               L/R                       L/R
                                                             SDA5550              SDRAM                    HP          AudioAmp
                                                                                                        TDA1308T       TDA1517P
                               12V                                                                                    L       R




                                                                   Figure 1 System Block Diagram

                      L5-A board supports 5 types of video and graphics inputs. These inputs are: Analog
                      terrestrial tuner input for multisystem PAL/SECAM transmission, SCART input (x2), S-VHS
                      input, RCA input and analog PC video input.

                      The analog RGB signals coming from the PC input (via D-Sub15 connector P401) are
                      directly connected to the gm2221 analog input port.

                      One EDID IC (U400) is provided on board to support VESA standard plug-and play
                      compatibility.




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                      On the board, one high quality video decoder (U100) is provided (VPC3230D of Micronas)
                      to process video inputs coming from the video sources. The video processor can process 3
                      composite video inputs and 1 S-Cideo input from the NTSC/PAL video sources. The CVBS
                      output recovered from the tuner module is made available to one of the video inputs of the
                      video decoder.

                      The digitized video output (in ITU-656 format) from U100 is fed to the dedicated video Port
                      of gm2221 for decoding and processing.

                      Gm2221 makes it possible to perform scaling and de-interlacing for the video input.

                      A 4Mbit serial flash ROM (U503) is used for storing system firmware. Also the footprint for
                      a parallel flash ROM, which can be upto 2Mbits, is available on the board. This option can
                      be used either for development or for production purposes.

                      The gm2221 provides direct connect via the integrated LVDS transmitters to LCD panels
                      with integrated LVDS receivers. Both single LVDS (via S503) and double LVDS(via S502)
                      panels can be supported directly from the L5-A main-board. For single LVDS panels, only
                      S503 connector is soldered on the main-board, which is a 20 pin connector. For Double
                      LVDS panels, only S502 connector is soldered on the main-board, which is a 30 pin
                      connector. For supporting different LVDS panels, different LVDS cables (either single or
                      double LVDS) can be made used.

                      For supporting different single or double TTL panels, a daughter board interface is used via
                      40 pin S506 connector. On this connector, the signals are 3x8bit RGB with TTL control
                      signals (i.e. HSync, VSync, CLK, O/E etc.) to support a wide variety of LCD panels.
                      Depending on the panel used, different daughter boards will be used to support that
                      particular panel. For single TTL panels, the daughter board will just be a routing the RGB
                      and control signals to the particular connector interface for that particular panel. For double
                      TTL panels, there will be two LVDS receiver IC's on the daughter board (double TTL is not
                      directly from GM2221 but double LVDS is supporter due to IC packaging problems) to
                      demodulate double LVDS signal into double TTL signal.


                      The LCD panel resolution supported can be up to SXGA at 75 Hz or UXGA at 60 Hz.

                      It is important to note that at any point in time gm2221 could drive only one type of Panel.
                      When LVDS Panel is connected (to connector S503 or S502) ensure that the panel
                      backlight is connected to S508. The integrated PWM output from gm2221 is used to
                      control the LCD panel backlight intensity for dimming functions.

                      The on screen display is implemented using OSD capability of gm2221. Infra Remote (IR)
                      controller connector (S507) is provided as a primary control interface for connecting IR
                      detector to the GPIO of gm2221. An IR remote controller unit and detector provide remote
                      OSD menu access at user convenience.




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                      A keypad connector (S507) is provided which utilizes the integrated low bandwidth ADC in
                      gm2221 for scanning 5-6 keys (menu,V+,V-,P+,P- keys standard- source key optional) on
                      the keypad. The keypad allows access to the OSD without using the remote IR controller.


                      The L5-A board also has In System Programming (ISP) capability for the external flash
                      ROM using DDC2Bi. This can be done using the D-Sub 15 (PC) connector on the board.
                      ISP can also be performed using G-probe through the RS232 interface.

                      One channel of the dual channel FET power switch (U602) is used to control the power
                      sequencing to the LCD panel. Depending on the type of the panel, the input voltage to this
                      FET device can be chosen as shown below:

                      For +3.3V panels           J601 is soldered on the main-board
                      For +5V panels             J600 is soldered on the main-board
                      For +12V panels            J603 is soldered on the main-board


                      An LM2576, a step-down regulator IC (U600), is used to generate the main +5V_STBY
                      voltage on the board. This IC can deliver up-to 3 Ampers of 5Volts. There is no stand-by
                      control for this regulator, which means this IC is always on, as soon as power is supplied
                      to the board.

                      U603(+3.3V_STBY) and U605 (+1.8V_STBY) linear regulators are used to supply the
                      voltage necessary for the GM2221 IC and some peripherals. These voltages are also
                      available in stand-by mode to power the microprocessor inside gm2221, LED, IR receiver
                      IC and EEPROM. These devices are necessary to wake up the board from stand-by state.

                      Second channel of the dual channel FET power switch (U602) is used to control cut some
                      voltages in stand-by mode. These voltages are +5V, +3.3V and +2.5V. These voltages are
                      used by the video processor (VPC 3230D), audio processor (MSP 34x0G), teletext
                      processor (SDA5550), tuner and some peripheral IC's and circuitry. In order to limit the
                      stand-by power consumption, these voltages are not available in stand-by mode. Also the
                      audio amplifier (TDA1517) is also in its stand-by mode using its dedicated stand-by pin.


                      The board employs MSP3410G, a multi-system audio processor solution from Micronas.
                      The system supports 4 audio input ports, one of which is not used on the L5-A board.
                      Audio output is provided with speaker and headphone jacks (S409, S401) provided on the
                      board. The sound IF signal from the tuner is connected to the audio processor directly.




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                      4. GM2221 LCD TV CONTROLLER
                      The gm2221 IC is a highly integrated single channel scaler that can be used for both LCD
                      monitors up to SXGA/UXGA resolutions and rear projection systems with DLP and HTPS
                      LCD engines up to 1280x720 (720P). Some of the key features include:
                         



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