Toshiba 2555DB User manual

2552D8/2852D8
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SAFETV INSTRUCTIONS
WARNING: BEFORE SERVICING THIS CHASSIS, REAO THE "X-RAY RAOIATION PRECAUTION", "SAFETY
PRECAUTION" ANO ·PRODUCT SAFETY NOTICE" INSTRUCTIONS BELOW.
X-RAY RADIATION PRECAUTION
1. The E.H.T. must be checked every time the
receiver is serviced to ensure that the C.A.T. does
not emit X-ray radiation as result of excessive
E.H.T. voltage. The nominal E.H.T. for this receiver
is 26.5 kV at zero beam current (minimum
brightness) operating at 240V a.e, The maximum
E.H.T. voltage permissible in any operating
circumstanees must not exeeed 29.0 kV. When
cheeking the E.H.T., usa the 'High Voltage Check'
procedure in this manual using an aeeurate E.H.T.
voltmeter.
2. The only source of X-RAY radiation in this reeeiver
is the C.A.T. To prevent X-ray radiation, the
replaeement C.R.T. must be identical to the original
fitted as specified in the Parts List.
3. Some eomponents usad in this reeeiver have safety
related eharacteristics preventing the C.A.T. from
emitting X-ray radiation.
For continuad safety, replaeement component
should only be made after referring the Produet
Safety Notiee below.
SAFETY PRECAUTION
1. This receiver has a nominal working E.H.T. voltage
of 24.5 kV. Extreme eaution should be exercised
when working on the reeeivar with the baek
removed.
Do not attempt to service this receiver if you are
not conversant with the preeautions and procedures
for working on high voltage equlpment. -,
When handling or working on the C.A.T., a1ways
diseharge the anode to the receiver ehassis before
removing the anode eap
The C.A.T., if broken, will violently expel glass
fragments. Use shatter proof goggles and take
extreme care while handling.
Do not hold the C.A.T. by the neek as this is a very
dangerous practice.
2. It is essential that to maintain the safety of the
eustomer all eable forms be replaced exactly as
supplied from factory.
3. A small part of the chassis used in this receiver is,
when operating, at approximately half mains
potential at·all times. It 15 therefore essential in the
interest of safety that when serving or connectíng
any test equipment the receiver should be supplied
via a suitable isolatíng transformer of adaquate
rating.
4. Raplaee blown fusas within the receivar with the
fuse specified in the parts list.
5. When replaeing wires or components to terminals
or tags, wind the leads around the terminal before
soldering. When replaeing safety components
identified by the international hazard symbols on
the circuit diagram and parts list, it must be a
Toshiba approved type and must be mounted as
the original.
6. Keep wires away from high temperature cornpo-
nents.
PRODUCT SAFETY NOTICE
Many electrical and meelianieal eomponents in this ehassis have special safety-related characteristics. These
characteristíes are often passed unnoticed by a visual inspection and the X-ray radiation protection afforded by
them cannot necessarily be obtained by using replacements rated at higher voltages or wattaga, etc.
Componants which haya these special safety characteristies in this manual and its supplements are identified by
the international hazard symbols on the schematic dlagram and parts list. Before replacing any of these
components read the parts list in this manual carafully. Substituta replaeement eomponents which do not have
the same safety characteristics as specified in the parts llst may create X-ray radiation.
-2-

255508/285508
SPECIFICATlONS
Input Power Ratlng:
ABrial Input Impedance:
Receivinljl Channels:
Intermediat. Frequencies:
Picture Tube:
Sound Output:
Speakers:
Aux. Terminals:
Cabinet:
Dimensions:
Mass:
Features:
100 watts (255508), 105 Wlltts (285508), AC 220-240 volts, 50 Hz
75 ohm unbalanced type tor UHF
PAL I Standard:
UHF ...................•.........•.....•...................................•................ channels 21 to 68
Picture I-F carrier frequency 39.5 MHz
Sound I-F earrier frequeney 33.5 MHz
Colour sub-carrler frequeney 35.07 MHz
25 inehes, A59EAK71X01, 590 mm (diagonal of viewable area), 110
0
defleetion : (255508)
28 inehes, A66EAK71X01, 660 mm (diagonal of viewable area), 110
0
defleetlon : (285506)
10.0 watts x 2
160 mm x 40 mm oval 2 pes (MAIN) 100 mm 2pcs (Hill Top) : (2555081
120 mm x 60 mm oval 2 pes (MAIN) 100 mm 2pcs (Hill Top) : (2855081
21 pin soeket, S-VIDEO, VIDEO/AUOIO INPUT soeket
Tabletype (255508) (285508)
571.3 mm
760 mm
480 mm
255208/285208
Height 527.5 mm
Width 676 mm
Oepth 440 mm
28.4 kg (255508),37.7 kg (285508)
Video input of PAl/3.58N/4.43N, TELETEXT reeeption, NICAM Oigital stereo system,
OFF-timer
SPECIFICATIONS
Input Power Rating:
Aerial Input Impedance:
Receiving Channels:
Intermediate Frequencies:
Picture Tube:
Sound Output:
Speakers:
Aux. Terminals:
Cablnet:
Dimensions:
Mass:
Features:
100 watts (2552081, 105 watts (285208), AC 220-240 volts, 50 Hz
75 ohm unbalanced type for UHF
PAL I Standard:
UHF ehannels 21 to 68
Picture I-F carrier frequency 39.5 MHz
Sound I-F earrier frequency . 33.5 MHz
Colour sub-earrier frequency 35.07 MHz
25 inches, A59EAK71X01, 590 mm (diagonal of viewable area), 110
0
defleetion : (255208)
28 inehes, A66EAK71X01, 660 mm (diagonal of viewable area), 110
0
detreetion : (285208)
10.0 watts x 2
160 mm x 40 mm oval 2 pes (MAIN) : (255208)
120 mm x 60 mm oval 2 pes (MAIN) : (285208)
21 pin socket, S-VIOEO, VIDEO/AUOIO INPUT socket
Table type (255208) (2852081
Height 516 mm
Width 640 mm
Oepth 447 mm
29.6 kg (255208), 33.0 kg (285208)
Video input of PAL/3.58N/4.43N, TELETEXT reception, NICAM Oigital stereo system,
OFF-timer
568.5 mm
700 mm
474 mm
Specifications are subject to change without notice.
-3-

FRONT CONTROLS ANO REAR VIEWS (255508)
HORIZ_ P1CTURE POSITION
AERIAL TERMINAL
-4-

FRONT CONTROLS ANO REAR VIEWS (285508)
VIDEO-3 POWER INDICATOR
HEAD PHONE
D
-5-

FRONT CONTROLS ANO REAR VIEWS (255208/2852D8)
21-pin SOCKET 2 (S-VIDEO/AV)
21-pin SOCKET 1 (FULL)
HORIZ. PICTURE POSITION
AERIAL TERMINAL
-.6-

REMOTE HAND HELD UNIT
TXT/TV CALL/~ ~
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MENU ~~CDIII!
CJDDCJ
CCCC
CT-9785
KEY ASSIGNMENT
<!) ONISTAND-BY
a:a::........... MUTE
CALL DISPLAY CALL
MENU TUNING s OTHER MENU
~ PICTURE MENU
P SOUND MENU
CD I/II..... < TV MODE> .......... STEREO BILlNGUAL
1-9, O TEN KEY
-1·- 1 or 2 place
-E) VIDEO INPUT (EXTERNAL INPUT SOURCE SW.)
..:::1 VOLUME
+LEVEL PLUS (VOLUME, MENU)
LEVEL MINUS (VOLUME, MENU)
... UP (POSI., CH., TEXT PAGE)
... DOWN (POSI., CH., TEXT PAGE)
TXT/TV TEXT, MIX, TV MODE SW.
rffi HOLD
@........... < TEXT MODE> REVEAL I CONCEAL
@i) <TEXT MODE> F-T-B
(FULL, TOP, BOTTOM)
TELE-
TEXT
®/@ ........ TIME DISPLAY (TV MODE)
TEXT CLEAR (TEXT MODE)
@)........... INDEX, INITIAL
FLOF COLOUR KEY (4 key used)
RedlGreenNellow/Blue
-7-

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-8-

WARNING: BEFORE SERVICING THIS CHASSIS, READ THE ·X-RAY RADIATION PRECAUTION", ·SAFETY
PRECAUTION" AND ·PROOUCT SAFETY NOTICE" ON PAGE 2 OF THIS MANUAL.
INSTALLATION ANO SERVICE ADJUSTMENTS
GENERAL INFORMATlONS
AII adjustments are thoroughly checked and corrected
when the receíver leaves the facfory. Therefore the
receiver should operate normally and produce proper
colour and B/'IN pictures upon installation. However.
several minor adjustments may be required
dependíng on the particular location in which the
receiver is operated.
This receiver is shipped completely in cardboard
carton. Carefully draw out the receíver trom the carton
and remove all packing materlals, Plug the power cord
into a convenient 240 volts 50 Hz AC two pin power
outlet. Turn the receiver ON. Check and adjust all the
customer control s such as BRIGHTNESS,
CONTRAST and COLOUR Controls to obtain natural
colour or B/'IN picture.
AUTOMATIC DEGAUSSING
A degaussing coil is mounted around the picture tube
so that external degaussing after moving the receiver
is normally unnecessary, providing the receiver is
properly degaussed upon installation. The degaussing
coil operates for about 1 second after the power to the
receiver is switched ON. If the set is moved or faced
in a different direction, the power switch must be
switched off at least 30 minutes in order that the
autornatic degaussing clrcuit operates properly.
Should the chassis or parts of the cabinet become
magnetized to cause poor colour purity, use an
external degaussing coil. Slowly move the degaussing
coil around the faceplate of the pícture tube. the sides
and front of the receiver and slowly withdraw the coil
to a distance of about 2 m befo re disconnecting it
from AC source. If colour shadíng still persists.
perform the COLOUR PURITY ADJUSTMENT and
CONVERGENCE AOJUSTMENTS procedures.
HIGH VOLTAGE CHECK
CAUTION: There is no HIGH VOLT AGE AOJUST·
MENT on this chassis.
1. Connect an accurate high voltage meter to the
second anode of the picture tube.
2. Turn on the receiver. Set the BRIGHTNESS and
CONTRAST Controls to minimum (zero beam
current).
3. High voltage will be measured below 29.0 kV.
HORIZONTAL CENTRE ADJUSTMENT
1. Receive too UK PHILlPS pattern.
2. Set the contrast and colour to centre. and the
brightness to centre.
3. Adjust H. CENTER USER Control (R452) so the
pattern centre can be located at the screen centre.
FOCUS AOJUSTMENT
Adjust FOCUS Control on FLYBACK TRANS. (T461) tor
well defined scanning lines in the centre area on the
screen.
SIF FM DET (LG04) ADJUSTMENT (NICAM BOARD)
1. Connect SIF generator through 0.01 pF capacitor to
pin 01 01 POOl on NICAM Board.
2. Connect the oscilloscope to pin 9 01IC003.
3. Set up the SIF generator as described below.
Sound carrier frequency: 6.0 MHz
Modulation frequency : 1000 Hz
Frequency deviation : ± 15 kHz
Signallevel : 100 dBp (50 ohm load)
4. Adjust LG04 for the maximum response of 1000 Hz
det-out on scope.
-9-

PAL MATRIX ADJUSTMENT
1. Tune in the colour programme 01the Philips pattern.
2. Set the COlOUR Control to obtain the proper
colour.
3. If the PAl MATRIX adjustment ts tn correct, the
Venetian Blind would appear in tha colour bars area.
This casa needs the adjustmant.
4. At the first, adjust Dl PHASE ADJ. Coil (l551) to
minimiza the Venetian Blind.
5; Next adjust lH-OL ADJ. VR (R551) to minimiza the
Blind.
6. If the Vanetian Blind stíll ramains, adjust 1H-Dl
PHASE ADJ. Coil (L551) to minimize the Blind
again.
7. Repeat the item 5 and 6 procedures, adjust the
R551 and l551 until the Blind does not appear.
CRT GREY SCALE ADJUSTMENT
1. Tuna in an active channel.
2. Set the SERVICE SW. (S202) in the "H. UNE"
position.
3. Turn the SCREEN Control (on T461) fully counter-
clockwise. .
4. By rotating the RED, GREEN and BLUE CUT OFF
Controls (R557, R558, R559) to the mid position.
5. Set the GREEN and BlUE ORIVE Controls (R252,
R253) to the center.
6. Rotate the SCREEN Control gradually clockwise
until the first line appears slightly on the sereen.
Set the SCREEN Control to this position.
7. Adjust the CUT OFF Controls to obtain the slightly
lighted horizontal lines in the same levels of three
eolours (RED, GREEN and BLUE).
The lines may look like white if the CUT OFF
Controls are adjusted properly.
8. Set the SERVICE SW. (S202) in the "RECEIVE"
position.
9. Set the CONTRAST and COlOUR Controls to
minimum, and BRIGHTNESS Control to the
maximum.
10. Adjust the BlUE and GREEN ORIVE Controls
(R252/R253) to obtain proper white-balanced pieture
in high light areas.
11. Set the BRIGHTNESS and CONTRAST Controls to
obtain dark grey raster. Then check the white
balance in low brightness. 11the white balance is not
proper, retouch the CUT OFF Controls and ORIVE
Controls to obtain a good white balance in both low
and high light areas.
SUB-BRIGHTNESS ADJUSTMENT
1. Tune in a colour programme.
2. Set the CONTRAST Control to the minimum and
the BRIGHTNESS Control to the centre.
3. Set the COLOUR Control to the centre.
4. Set the SUB-BRIGHT. Control (R255) to the centre
and leave the receiver 10rfive minutes in this state.
5. Watehing the picture well, adjust the SUB-BRIGHT.
Control in the position where the pícture- does not
show evidence of blooming in high bright area and
not appear too dark in low bright portion.
6. Check the proper picture variation by rotating the
CONTRAST and BRIGHTNESS Controls to both
extremes.
7. If the picture does not appear dark with the
CONTRAST and BRIGHTNESS Controls turned to
the minimum, or not appear bright with the controls
turned to the maximum, adjust ths SUB-BRIGHT.
Control again tor the acceptable picture.
-10-

EXTENSION CABLE SET
1. Extention Cable Set is available for servicing modules of C2DB cnassís,
For 2545DB chassis, however, this cable is used for CHROMA Board.
2. Identify number of pins by reading surfaee-print on the pe board of cable set,
Part No.
Extension Cable Set
Descriptlon
23305270
C (8P)
E (9P)
Note: Identífy nurnber 01 píns
by readíng surface-prínt on the
pe board 01cable set.
(ex.) PB3438-1-15
T
15 pins
-11-

TO USE THE CABLE SET
1. Unsolder corners on shielding case of module.
which are markedwith arrowin the figure.
TO MODULE
2. Remove shielding case. and pull up module to
disconnect.
3. Connect Extension Cable Set to module and Main
board'.
-12-

HOW TO MAKE THE CHASSIS STAND FOR REPAIR OF THE ~3~~g=
1. Disconnect the lead wires for the speaker fixed to
the degausser coil with three omega clips.
2. Lifting up slightly, pull out the chassis from the
front mask.
3. There is a slit at the 18ftfront of the bottom side of
the front mask. Lift up the left side of the chassis
and ínsert the hook at the right side into the slit.
-13-

4.2555D8:
To retain the chassis, -úse the screw hole (boss) 'al
the upper 19ftfor back cover positioning.
2855D8:
To retaln the chassis, use the upper left boss
(hlghest boss) which is marked with No. 29.
5. Fix it with screws for back cover fixing.
Upper hole of the chassis frame fQr 2555, 2855 and
the lower hola of the chassis trame for 2155 series.
6. After repaír works, resto re the unit by reversing the
aboye steps.
-14-

HOW TO MAKE THE CHASSIS STAND FOR REPAIR OF THE ~~~~g~
1. Remove the wire set tor the loud speaker from the
holder.
2. Remove the horn speaker unit (unscrew the fixing
screws).
3. Lift up the chassis in such manner that it stands
against the inner side surface of the front mask.
4. Using the screws which have been removed when
disconnecting the front mask and the back cover,
screw the chassis to the side of the front mask.
5. To restore, perform the aboye steps in opposite
order.
-15-
Upper hole for 2852 and
the lower hole for 2552
series.

SERVICE MODE GENERAL INSTRUCTIONS
1. ENTERING TO SERVICE MODE
1) Press « button once on
Remote Control. 2) Press
.al< button again to
keep pressing .. 3) Keep pressing the
« button.
press MENU button on TV set.
11 03
MOO 1 .
(Servicemode display)
2. SELECTING THE ADJUSTING ITEMS
Every pressing of CHANNEL ... button changes the adjustment items in the following arder. ('f' button for reverse
arder.)
3. ADJUSTING THE DATA
Pressing of VOLUMÉ ... or 'f' button will change the value of data in the range from 00 to FF. The variable range
dependa on tlie adjusting item.
4. NORMAL OPERATI9N· ON THE SERVICE MODE
Press MENU button on TV.
Normal operation mode
Press
M
~----ll---- Symbol Press
~--+-- Item No. _ __.;..=:.......O~
.,----ll---- Data
5. EXIT FROM SERVICE MODE
Press POWER button on the remate control to turn off the TV once.
SUB DATA ADDITIO~AL DESCRIPTION
Symbol Description
HIT V amplitude adjustment.
OI
\ I
'- ....
.... _
-16-

Symbol Description
UN
o
V linearity correction 1.
+
o
linearity balance between top and
bottom screen.
VSC
o
V Jinearity correction 2.
+
VPC
o
VCP
Setting of amount of V amplitude
correction against variation of screen
brightness.
linearity balance between
top/bottom and center.
V picture position adjustment.
WIO
-17-
H amplitude adjustment.
/0.....'
I \
, ,
\ I
" .-
...

Symbol Descrlption
DPC H pin-cushion dístortion correction.
/'
{,
,
I
I
III
II
\j_
\1
CNR H pin-cushion distortion correction
at four corners.
"O
I ,
~- -~
KEY
Pedestal dístortion correction.
XX
HCP Setting of amount of H amplitude
correction against variation of screan
brightness.
VMC V linearity correction.
linearity balance at 1/4, 3/4 areas
from topo
-
O +
,#
...
---..... .. -
o
('¿.
Linearity •~
L~:'
-18-

ADJUSTMENTPROCEDURE
Adjuatment parta or Input point/ Adjustment slgnal Adjustment condltlona and procedures
Bu. control Item Output polnt
: Horizontal amplitude Visual check of picture WG Philips pattern 1. Conditions: After V. HEIGHT, VERT POSITION
adjustment (WIO) (Bus control) and H. CENT have been adjusted, set
: Pln distortion Do not use the Philips the controllers as follows:
compensation amount pattem of Contrast Max
adjustment (OPC) FRANCESECAM. Brightness: Center
: Keystone distortion Color: Center
compensation amount 2. Adjustment procedure
adjustment (KEY) a. Adjust the horizontal amplitude by the sub
address WIO.
Adjust so that the left and right white flags of
Philips pattem disappear at the very limits.
b. Make
the Ieft and right vertical bars straight by
the sub address OPC.
c. Compensate Ihe kay distortion by the sub
address KEY.
d. Again, adjust the sub address WIO.
WG Philips pattern 1. Conditions: Contrast Max
: HEIGHT (HIT) Visual check of pieture Brightness: Center
: VERT. =osmon (Bús control) Do
not use the Philips
Color. Center
patternof 2. Adjustment procedure
FRANCESECAM. a. By the bus address VPS, adjust V. position so
that the circle of Philips pattem comes 10 Ihe
vertical cantero
b. AdjuSl HIT so Ihat the upper and lower flags of
Philips pattem disappear al tha very limita.
-19-

ROM DATA LlST FOR uc BUS CONTROL (Reference Value)
Symbol Comment
Data
25550B 28550B 25520B 28620B
Moo MOOEO 51 51 51 51
M01 MOOE 1 33 33 33 33
M01 MOOE 1 USE ALPS TUNER 01 01 01 01
M02 MODE2 03 03 02 02
M03 MODE 3 17 17 49 49
HIT HEIGHT
* 30
* 30
* 30 * 30
UN V. LlNEARITY 32 32 32 32
VSC V. S-CORRECTION 32 32 32 32
VPS V. POSITION
* 07 * 07 * 07 * 07
VCP V. COMPENSATION 30 30 30 30
WIO H. WIOTH
* 22 * 26
* 22 * 26
OPC OPC
* 26 * 24 *26
* 24
CNR OPC CORNER P44V32 32 P44V32 32
KEY KEYSTONE
* 09 * 09 * 09 * 09
HCP H. COMPENSAT10N 10 10 10 10
VMC V, M-CORRECTION 52 41 52 41
SHI 16:9 SUB HEIGHT 00 00 00 00
SU 16:9 SUB V. UNEARITY 32 32 32 32
SVS 16:9 SUB V. S-CORRECTION
17
17 17
17
SOP 16:9 SUB OPC P18V21 P17V21 P18V21 P17V21
SCN 16:9 SUB CORNER 30 30 30 30
WCT WOOFER FC SET 12 08 12 12
BAC BASS CENTER 40 34 50 50
TRC TREBLE CENTER 48 52 44 44
BAX BASS MAX 79 79 79 79
WON BAZOOKA AUTO 05 30 06 06
WOF BAZOOKA OFF 20 47 25 25
BAE BASS UP 01 03 01 01
TRE TREBLE UP 12 17 10 10
VOE VOLUP 02 02 00 00
WFL WOOFER LEVEL 100 100 100 100
EMX NICAM OFF LEVEL (PHIL) 252 252 252 252
EMN NICAM ON LEVEL (PHIL) 100 100 100 100
FMA FM INPUT ATI (PHIl) 00 00
00
00
STS STEREO SEPARATION -
-
--
* Mark items should be adjusted.
-20-