Toshiba 2837DD User manual

SERVICE DATA
FILE NO. 050-751
PAL-B/G SYSTEM
TOSHIBA
COLOUR TELEVISION
2837DD,
2537DD
7037DD
Note: The specifications of model 7037DD are the same as
those of model 2837DD which are described below.
SPECIFICATIONS
Input Power Rating:
Aerial Input Impedance:
Receiving Channels:
Intermediate Frequencies:
Picture Tube:
Sound Output:
Speakers:
Aux. Terminals:
Cabinet:
Dimensions:
Weight:
Features:
147 W (2837DD), 143 W (2537DD), AC 220 ~ 240 V, 50 Hz
75 ohm unbalanced type for VHF, UHF and CATV
CCIR (B/G.PAL) TV Broadcast Standard:
channels 2 to 4, 5 to 12, S1 to S41
channels 21 to 69
Picture I-F carrier frequency 38.9 MHz
Sound I-F carrier frequency ...
Colour sub-carrier frequency .. 34.47 MHz
28 inches, A66ECY 13X31, 660 mm (measured on diagonal of viewable picture area)(2837DD),
25 inches, AS9ECY 13X31, 590 mm (measured on diagonal of viewable picture area)(2537DD),
110° deflection
10.0 W x 2 (at 10% Distortion MAIN), 5.0 W x 2 (at 10% Distortion Dolby)
120 mm x 80 mm oval 2 pcs
21 pin socket (FULL), 21 pin socket (S-VIDEO/AUDIO) S-VIDEO, VIDEO/AUDIO INPUT socket
Table type
(2837DD) (2537DD)
516 mm
640 mm
447 mm
33 kg (2837DD), 27.5 kg (2537DD)
Video input of PAL-B/G, TELETEXT reception, OFF-timer, German stereo/bilingual,
Dolby surround
Specifications are subject to change without notice.
Printed in Japan Jul. 1994

SAFETY INSTRUCTIONS
WARNING: BEFORE SERVICING THIS CHASSIS, READ THE "X-RAY RADIATION PRECAUTION", "SAFETY
PRECAUTION" AND "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.R.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 220V a.c. The maximum
E.H.T. voltage permissible in any operating
circumstances must not exceed 29.0 kV. When
checking the E.H.T., use the ‘High Voltage Check’
procedure in this manual using an accurate E.H.T.
voltmeter.
2. The only source of X-RAY radiation in this receiver
is the C.R.T. To prevent X-ray radiation, the
replacement C.R.T. must be identical to the original
fitted as specified in the Parts List.
. Some components used in this receiver have safety
related characteristics preventing the C.R.T. from
emitting X-ray radiation.
For continued safety, replacement component
should only be made after referring the Product
Safety Notice below.
SAFETY PRECAUTION
. This receiver has a nominal working E.H.T. voltage
of 24.5 kV. Extreme caution should be exercised
when working on the receiver with the back
removed.
Do not attempt to service this receiver if you are
not conversant with the precautions and procedures
for working on high voltage equipment.
When handling or working on the C.R.T., always
discharge the anode to the receiver chassis before
removing the anode cap
The C.R.T., if broken, will violently expel glass
fragments. Use shatter proof goggles and take
extreme care while handling.
Do not hold the C.R.T. by the neck as this is a very
dangerous practice.
. It is essential that to maintain the safety of the
customer all cable 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 is therefore essential in the
interest of safety that when serving or connecting
any test equipment the receiver should be supplied
via a suitable isolating transformer of adequate
rating.
. Replace blown fuses within the receiver with the
fuse specified in the parts list.
. When replacing wires or components to terminals
or tags, wind the leads around the terminal before
soldering. When replacing 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.
. Keep wires away from high temperature compo-
nents.
PRODUCT SAFETY NOTICE
Many electrical and mechanical components in this chassis have special safety-related characteristics, These
characteristics 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 wattage,
Components which have these special safety characteristics in this manual and its supplements are identified by
the international hazard symbols on the schematic diagram and parts list. Before replacing any of these
components read the parts list in this manual carefully. Substitute replacement components which do not have
the same safety characteristics as specified in the parts list may create X-ray radiation.
etc.

FRONT CONTROLS AND REAR VIEWS
VIDEO-3: S-VIDEO TERMINAL MAINS SWITCH
VIDEO-3: INPUT SOCKET POWER INDICATOR
MENU SELECT REMOTE EYE
VOLUME DOWN POSITION UP
VOLUME UP POSITION DOWN
21-pin SOCKET 2 (S-VIDEO/AV)
21-pin SOCKET 1 (FULL)
HORIZ. PICTURE POSITION
AERIAL TERMINAL

REMOTE HAND HELD UNIT
KEY ASSIGNMENT
(0) dseasenied ON STAND-BY (F + ; VTR ON STAND-BY)
DK vreresescees MUTE
CALL ...... DISPLAY CALL
Few eet FUNCTION KEY FOR VTR
VTR (To push double for VTR & SERVICE Operation)
co. <TV MODE > --------- TUNING & OTHER MENU
<TEXT MODE > -----F-T-B (FULL, TOP, BOTTOM)
>” eens PICTURE MENU
d seeeines SOUND MENU
OOM ..... <TV MODE > «++ STEREO BILINGUAL
=? <TEXT MODE > ---- REVEAL / CONCEAL
1~9,0... TEN KEY
-fee 1 or 2 place
Eb) ce VIDEO INPUT (EXTERNAL INPUT SOURCE SW.)
ZA eile VOLUME
RY ah iectea: LEVEL PLUS (VOLUME, MENU)
ee ecietctas LEVEL MINUS (VOLUME, MENU)
A Ao UP (POSI., CH., TEXT PAGE)
We esesees DOWN (POSI., CH., TEXT PAGE)
TXT/TV....... TEXT, MIX, TV MODE SW.
Sas TIME DISPLAY (TV MODE)
ae oes TEXT CLEAR (TEXT MODE)
TEXT | Ghee INDEX
FLOF COLOUR KEY (4 key used)
RC) ; Red GO: Green
YO ; Yellow CO ; Cyan
TOSHIBA
To push with F Key
(ly ON STAND-BY [gl - STOP
VTR
440°" FF / CUE »> = REV / REW
CT-9678

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WARNING:
BEFORE
SERVICING
THIS
CHASSIS,
READ
THE
“X-RAY
RADIATION
PRECAUTION”,
“SAFETY
PRECAUTION” AND “PRODUCT SAFETY NOTICE” ON PAGE 2 OF THIS MANUAL.
INSTALLATION AND SERVICE ADJUSTMENTS
GENERAL INFORMATIONS
All adjustments are thoroughly checked and corrected
when the receiver leaves the factory. Therefore the
receiver should operate normally and produce proper
colour and B/W pictures upon installation. However,
several minor adjustments may be required
depending on the particular location in which the
receiver is operated.
This receiver is shipped completely in cardboard
carton. Carefully draw out the receiver from the carton
and remove all packing materials. Plug the power cord
into a convenient 220 volts 50 Hz AC two pin power
outlet. Turn the receiver ON. Check and adjust all the
customer controls such as BRIGHTNESS,
CONTRAST and COLOUR Controls to obtain natural
colour or B/W 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 one hour in order that the
automatic degaussing circuit 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 picture tube, the sides
and front of the receiver and slowly withdraw the coil
to a distance of about 2 m before disconnecting it
from AC source. If colour shading still persists,
perform the COLOUR PURITY ADJUSTMENT and
CONVERGENCE ADJUSTMENTS procedures.
HIGH VOLTAGE CHECK
CAUTION: There is no HIGH VOLTAGE ADJUST-
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.
HEIGHT ADJUSTMENT
1. Receive the UK PHILIPS pattern, and set the
contrast, colour and brightness to centre.
2. Adjust HEIGHT Control (R351) so that white blocks
at top and bottom of the picture are just masked.
HORIZONTAL CENTRE ADJUSTMENT
1. Receive the UK PHILIPS 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 ADJUSTMENT
Adjust FOCUS Control on FLYBACK TRANS. (1461) for
well defined scanning lines in the centre area on the
screen.
PAL MATRIX ADJUSTMENT
1.
2.
3.
Tune in the colour programme of the Philips pattern.
Set the COLOUR Control to obtain the proper
colour.
If the PAL MATRIX adjustment is incorrect, the
Venetian Blind would appear in the colour bars area.
This case needs the adjustment.
. At the first, adjust DL PHASE ADu. Coil (L551) to
minimize the Venetian Blind.
Next adjust 1H-DL ADJ. VR (R551) to minimize the
Blind.
. If the Venetian Blind still remains, adjust 1H-DL
PHASE ADJ. Coil (L551) to minimize the Blind
again.
. Repeat the item 5 and 6 procedures, adjust the
R551 and L551 until the Blind does not appear.
CRT GREY SCALE ADJUSTMENT
10.
11.
Pm Nes
Tune in an active channel.
Set the SERVICE SW. (S202) in the “H. LINE”
position.
Turn the SCREEN Control (on T7461) fully counter-
clockwise.
By rotating the RED, GREEN and BLUE CUT OFF
Controls (R557, R558, R559) to the mid position.
Set the GREEN and BLUE DRIVE Controls (R252,
R253) to the center.
Rotate the SCREEN Control gradually clockwise
until the first line appears slightly on the screen.
Set the SCREEN Control to this position.
Adjust the CUT OFF Controls to obtain the slightly
lighted horizontal lines in the same levels of three
colours (RED, GREEN and BLUE).
The lines may look like white if the CUT OFF
Controls are adjusted properly.
Set the SERVICE SW. (S202) in the “RECEIVE”
position.
Set the CONTRAST and COLOUR Controls to
minimum, and BRIGHTNESS Control to the
maximum.
Adjust the BLUE and GREEN DRIVE Controls
(R252/R253) to obtain proper white-balanced picture
in high light areas.
Set the BRIGHTNESS and CONTRAST Controls to
obtain dark grey raster. Then check the white
balance in low brightness. If the white balance is not
proper, retouch the CUT OFF Controls and DRIVE
Controls to obtain a good white balance in both low
and high light areas.

SUB-BRIGHTNESS ADJUSTMENT
1.
2.
3.
Tune ina colour programme.
Set the CONTRAST Control to the minimum and the
BRIGHTNESS Control to the centre.
Set the COLOUR Control to the centre.
Set the SUB-BRIGHT. Control (R255) to the centre
and leave the receiver for five minutes in this state.
Watching the picture well, adjust the SUB-BRIGHT.
Control in the position where the picture: does not
show evidence of blooming in high bright area and
not appear too dark in low bright portion.
Check the proper picture variation by rotating the
CONTRAST and BRIGHTNESS Controls to both
extremes.
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 the SUB-BRIGHT.
Control again for the acceptable picture.

HOW
TO
MAKE
THE
CHASSIS
STAND
FOR
REPAIR
OF
THE
2835DB
(Model )
1.
Remove
the
wire
set
for
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 above steps in opposite
order.
Upper hole of the chassis
frame for 2835/2837 and
Lower hole of the chassis
frame for 2535/2537 series.

ADJUSTMENT METHOD FOR SERVICING
1. OUTLINE
Since each IC used is of I2C bus control type,
readjustment of the TVs also needs adjustment through
12C bus control.
In the service mode, sub-bright, deflection system sub-
adjustments, picture system sub-adjustments can be
made easily with user remote control unit.
2. SERVICE MODE OPERATION
2-1. How to Enter the Service Mode
@©+ &
(simultaneous push)
J
q) key
t Service mode
@key Service mode in
1
G)key
J
key
2-2. How to Exit from the Service Mode
Exit the service mode by turning the power on/off with
the remote control.
5. SUB DATA ADDITIONAL DESCRIPTION
17 HIT
met [ se
3. ADJUSTMENT IN THE SERVICE MODE
3-1. Service Mode Level Adjustments
(1) Push () + (4@ key (simultaneous push) (item UP)
or + key (simultaneous push) (item DN) to
select item to be adjusted.
(2) Adjust with the level UP/DN (VOL UP/DN key) key.
3-2. Other Service Mode Adjustments
()+ Q) key (simultaneous push) cut off:
(NO VERTICAL DEFLECTION) ON/OFF
4. SELF CHECK
(1) Indicates sync signal and acknowledgement of
each IC.
(2) Example of display on screen
.
ISYNG2
;
NG]
RED
indication
(with
aye
=
;
‘
_
6
whe
AS
background)
for
NG
PLL
‘PIF!
GR
NIGAM!
=
AUD
TEXT
RGBAvcD
EW
MEMORY
YELLOW indication GREEN indication for OK
(without background)
for TV model with
no circuit.
(3) Operation:
@®_ TV gets into service mode with key operation;
[© + S]-Orey +()key—> (4) key +(8)key
@ TV indicates screen with () + G)key.
V amplitude adjustment.

Linearity balance between top and
bottom screen.
V linearity correction 2.
Linearity
Linearity balance between
top/bottom and center.
V picture position adjustment.
Setting of amount of V amplitude
correction against variation of screen
brightness.
H amplitude adjustment.
-10-