Service Manuals, User Guides, Schematic Diagrams or docs for : NOKIA TV 7451=akai_tv-2550_stereoplus2

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7451=akai_tv-2550_stereoplus2


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    VI_,     -1.   V.   .I\__._




    (50 Hz, 4:3 / 16:9)                                      3 /I999


    GB Service manual             @I   Manuel de service
    @      Service-Manual         a    Manuale di servizio
    @      Serviceanvisning                       ..




    AKAI
    TV     2550-TN                TV   2851-T Multi White
    TV     2550-T Multi           TV   2852-T
    TV     2551 -TN               TV   2852-T Multi
    TV     2551-TN UK             TV   2852-TN UK
    TV     255%TN Multi           TV   2881-T Multi
    TV     2850-TN                TV   2881-T Multi UK
    TV     2850-T Multi           TV   3451-T Multi
    TV     2851-T Multi




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Frontend   Module




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                              SIgnal -and   Deflection       Procewng

                                            TDA 8854 H




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                           Power;Supply
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                      TEA 2262   kV5180A
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                                                                                                                            7



Changing the menu language
1. Press the yellow button to select the Vision menu.
2. Press the red button to select the Display set-up menu.
3. Change the menu language with cursor buttons.
4. Press the OK button to store the changes.
5. Press the TV button to exit.

Manual tuning
1. Select the programme number you want to tune.
2. Press the MENU button.
3. Select "Tuning" with the cursor buttons and press the
   OK button.
4. Select "Manual tuning" and press the OK button.
5. Select "Channel"-line with the cursor buttons and
   select the channel you want to watch with 3 digits.
6. Press the OK button to store.
7. Press the TV button to exit.

APSi (Automatic Programming System)
1. Press the MENU button.
2. Select "Tuning" with the cursor buttons and press the
   OK button.
3. Select "Automatic retuning" and press the OK button.
4. To retune the channels, press the red button.

                                                             lnitialFmtion of NVRAM
Service mode activation                                      lnitialization of NVRAM
Service mode can be enabled whenever     the receiver is     If the NVRAM is replaced, it must be initialized and
switched ON or is in stand-by mode.                          configured.

la)lf the receiver is switched ON, press the A- (volume      Note! The receiver doesn't start with uninitialized
    minus) button on local control unit and at the same      NVRAM, but stays in stand-by mode.
   time start entering password: MENU and TV. Release
   the A- button after the MENU button has been              1. Activate the service mode as described in "Service
    pressed.                                                    mode activation".

1b)lf the receiver is in stand-by mode, press the A-         2. lnitialize the NVRAM by entering the key code: BLUE,
   button on local control unit and at the same time start      2,5,4     and OK. Wait approx. 15 seconds and then
   entering password: MENU and TV. Release the A-               press the OK button again.
   button after the MENU button has been pressed.
   Switch ON the receiver by pressing the TV button.         3. Exit the service mode by pressing the TV-button.

2. Activate the service mode by pressing the i button and    4. Start the receiver and tune in one or more TV
   exit the service mode by pressing the TV button.             channels with the "manual tuning" method.

3. Disable the service mode by switching off the receiver    Note! The channel search doesn't work before the
   with the mains switch.                                    reference adjustments (code 12 and 73) have been made,
                                                             see page 10.
Note! Service mode activation stays enabled until the
receiver is switched off with the mains button.              5. Enter the service mode again and configure the TV set
                                                                as described in "Configuration and fault diagnosis".
                                                                (Check that the automatic configuration results in IIC
                                                                DEV l&2, AUTO OPT and IF OPT bytes are
                                                                corresponding to the actual configuration of the
                                                                TV set.)

                                                             6. Set the manual option bytes (TEXT OPT, HW OPT and
                                                                SW OPT) to correspond the actual configuration of the
                                                                TV set.

                                                             7. Make all necessary service adjustments (see section-
                                                                "SERVICE ADJUSTMENTS       VIA IIC BUS, page 9)
In service mode an adjustment menu is shown on the
screen.The adjustment number and name, initializing          Note! Ul VALU adjustment     must be done first.
(bottom) and adjustment (top) values are shown in the
menu.                                                        8. Disable the service mode by switching    off the receiver
                                                                with the mains switch.
Configuration and fault diagnosis                              Option byte description
The set must be configured after adding or removing any
option. By pressing the RED button in service mode, the        Bit   Description                   Setting   '1'   `0'
processor checks the configuration of the TV set and                                       76543210

shows the settings on the screen. The configuration can
be stored by pressing the OK button.                           0     TV tuner 5002PH5                        Yes   No
                                                               1     Decoder/sync processor TDA8854          Yes No
This feature can also be used in fault diagnosis. If an        2     Teletext processor TPU3050              Yes No
option bit is not `1' when it should be, the IC (or feature)   3     Sound processor MSP34xO                 Yes No
is either not present or faulty.                               4     Video matrix switch TEA6415             Yes No
                                                               5     PIP processor                           Yes No
                                                               6     PIP tuner                               Yes No
Note! IIC DEV 1, IIC DEV 2, AUTO OPT and IF OPT bytes
                                                               7     3D virtual sound processor              Yes No
are configured automatically every time the RED-button
is pressed.
TEXT OPT, HW OPT and SW OPT bytes must be set
manually.
                                                                     Power controller STV5180                Yes   No
                                                               :     Sound processor MSP3410                 Yes   No
Changing the option bytes                                      7     Reserved for production use             Yes   No
1. Select the configuration mode by pressing the RED
   button in the service mode.

                                                               0                                             Yes   No
                                                               1     16:9 picture tube                       Yes   No
                                                               3     Text memory 4 Mb DRAM                   Yes   No
                                                               4     Text memory 1 Mb SRAM                   Yes No
                                                                     Text memory 256 kb SRAM                 Yes   No
                                                               :     Tilt adjustment                         Yes   No
                                                               7     NICAM identification enabled            Yes   No



  Auto
                                                               0                                             Yes   No
                                                               1     I system in IF                          Yes   No
                                                                     D/K system in IF                        Yes   No
                                                               $4    L/L' system in IF                       Yes   No
                                                               5'    HEF4094B in IF                          Yes   No
 Manual


                                                               1     FLOF function enabled                   Yes   No
                                                               7,6,5 Text character set selected
                                                                     000 = West Europe / Czech
                                                                     001 = East Europe
               SW VER = pP software version.                         010 = West Europe/USA
               NVM VER = NVRAM software version.                     011 = West Europe /Turkish
                                                                     100 = East Europe 2
   Select IIC Device byte 1 - 2 or Option byte 1 - 5 with
   cursor buttons (up/down). The selected byte is shown
   highlighted.
   The name of a responding bit can be seen by using                 AIV connector installed                 Yes   No
   cursor buttons (left/right).                                      SVHS input in AV                        Yes   No
                                                                     3.58 MHz xtal installed                 Yes   No
   Set/clear   the bits with number buttons (0 . .. 7).

   Store the settings by pressing the OK button.                     Carrier mute enabled                    Yes   No
                                                                     Stand-by prevent                        Yes   No
   Return to the normal service mode by pressing the                 Autostart enabled (Special use only!)   Yes   No
   RED button.                                                       Pal + helper blanking 4:3               Yes   No
                                                                     El FB enabled (USER)                    Yes   No
                                                                     Hotel TV enabled                        Yes   No




                                                                     SW VER = uP software version



                                                                     NVM VER = NVRAM software version
                                                                                                                                                       9



Remote control buttons in service mode
When the receiver is in the service mode you can select
normal TV mode by pressing the TV button and return to
the service mode by pressing the i button.
Number and cursor buttons are used for service
adjustments. The OK button stores the settings.
The yellow button hides/shows the service menu to
simplify the picture adjustments.

Making adjustments for different picture formats
Make all adjustments with PAL signal unless otherwise                        2. Adjust with the cursor buttons (left/right).
mentioned. Make 4:3 set adjustments with normal
4:3(CLASSIC) picture format and 16:9 set adjustments
with wide picture format. Then make the necessary
adjustments with other picture formats/signals. The
required adjustments are shown in the table below.

Note! Check the configuration of the TVset before
making the adjustments and make only the necessary
adjustments.

                                                                             3. Store the new value by pressing the OK button.

Making a service adjustment                                                  Note!
1. Give a two digit code which determines an                                 l  To avoid incomplete adjustments store each
   adjustment (e.g. 00 = vertical shift, see the following                      adjustment in the memory immediately after an
   tables) with the number buttons. You can also select                         adjustment has been made.
   the adjustment with cursor buttons (up-/down).                            l  If an adjustment has to be made separately for
                                                                                different picture format/signal, select first the
Note! Power supply and UG2 adjustments                        must be done      normal mode by pressing the TV button and
before picture geometry adjustments.                                            select then the desired picture format/signal.
                                                                                Return to service mode by pressing the i button.




Picture    geometry       adjustments
                                                               r-                   el
                                        -                                           -    -    -
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                                                                                    0
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4djustment                              :ode
                                        -      OSD     name      Ii
                                                                 -
                                                                                    3
                                                                                    C    s-       2     Note!

Jertical off-centre    shift             00    V-SHIFT           K                       X              Center   line

Jertical   amplitude                     01    V-AMPL.           K                       X        K Adjust       upper   side

Jertical   slope                         02    V SLOPE           <                       X              Adjust   lower   part

Vertical   S-correction                  03    S-cot?!?.        X                        X

Vertical   zoom                          04    VER ZOOM         X)                       IX             Recommended        to use init value   first

Vertical   scrolling                     05    v SCROLL         Xl                       (X             Recommended        to use init value   first

Width                                    06    WIDTH            X                        X        X

Horizontal    shift deflection           07    H-SHIFT          X                        X    X   X

Parabola                                 08    PARABOLA         X                        X
Corner                                   09    CORNER           X                        X

Trapezium                               - 10   TRAPEZ           X
                                                                -                        -X   -
10
 Service adjustments
 0           Power supply            block                          K         Horizontal     deflection          block

 Supply voltage and protection circuit                              Focusing
 1. Set the brightness and the contrast to the normal               Set the brightness and the contrast to the normal level.
    level. Connect a universal voltmeter to the cathode of          Use the crosshatch pattern and adjust the picture for
    vo31.                                                           optimum resolution.

 2. Adjust the Ul voltage with Ul VALU in the service               (Screen grid voltage) Ug2 voltage
    mode. (The voltage depends on the picture tube type,               Set the brightness and the colour saturation to the
    refer to the section "Variable components").                       normal level and the contrast to minimum.

 3. Check the over-current protection after making any                  At the end of the vertical blanking, there is a black
    service operations in the primary circuit of the power              current measurement pulse (clamp pulse) at pin 9, 12
    supply. Switch the set to stand-by mode. Short circuit              and 15 of NHOI. Use an oscilloscope and find the
    the cathode of Vo5Q to the ground and keep the short                output stage with the highest cut-off (i.e. the highest
    circuit connected. When the over-current protection                 voltage during the black current measurement pulse).
    works correctly, the power supply stops permanently.
    Switch off the receiver by pressing the mains button.               Adjust the voltage of the upper clamp pulse to +I50 V
    Remove the short circuit and then switch on the                     with Ug2 (see figure).
    receiver by pressing the mains button.
                                                                    Note! Adjust the voltage with a c/amp pulse.



 AFC adjustments (code 12 and 13)
 I) The right value is found when while changing the
    value, the AFC display changes from 0 to 1.

 2) Adjust with a channel sent with L-standard.         Needed
                                                                                                       1-,
                                                                                                       t
                                                                                                         ._
                                                                                                            r--w-l
    only in multinorm TV sets.                                                                            150v


 Note! Use the right channel frequency.
 Tune the channel with "manual tuning method"
 (see page 7).
                                                                               ov




     Other   adjustments                                            -     -     -
                                                                          2


                                                                    2     5
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     Adjustment                                  Code   OSD name    B 2 2
                                                                    - - -           Note!

     Luma    delay                                11    Y-DELAY     X     X     X

     IF 33.9 reference     voltage   for AFC      12    REF 339                     I), 2)
     IF 38.9 reference     voltage   for AFC      13    REF 389                     1)
     STV5180      DAC value for Ul     control    14    Ul   VALU                   Must be done before     other adjustments!

     Red gain                                     15'   R GAIN

     Green    gain                                16    G GAIN

     Blue gain                                    17    B GAIN      -     -     -
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