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

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(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

TDA 2822 M

SDA30C263 I

SIgnal -and Deflection Procewng

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

Other adjustments - - -
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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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