Toshiba 2857DD User manual

TOSHIBA
FILE
NO.
030-9530
SERVICE MANUAL
COLOUR
TELEVISION
C5SS Chassis
285/DD

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
. 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 31.5 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 32.0 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 28.5 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.
2. 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, ett.
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 thes=
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.

FRONT CONTROLS AND REAR VIEWS
» Oey
ANY
(VIDEO-3)
S-VIDEO TERM. MAIN SW.
VIDEO-3 POWER IND.
HEAD PHONE ON-TIMER IND.
POSITION UP
POSITION DOWN
VOLUME UP
VOLUME DOWN
MENU
a ee? |
o a a
7 HL
—_ YL =|
- oO
TOSHIBA
5
ni
[e]
[oJ 3
[lc | al
(VIDEO-3)
EXT. SPK SW. S-VIDEO TERM.
EXT. SPK TERM. (MAIN) MONITOR OUT
EXT. SPK TERM. (SURROUND)
EXT. SPK TERM. (CENTRE)
AERIAL TERMINAL
VIDEO-3 (COMMON WITH FRONT TERM.)
21-PIN SOCKET 2 (S-VIDEO/AV)
21-PIN SOCKET 1 (FULL)

REMOTE HAND HELD UNIT
KEY ASSIGNMENT
ON/STAND-BY
. Sound mute
(Quick/advanced operation)
CALL (On-screen call)/ (index, initial) ........ TELETEXT MODE
>” een PICTURE MENU
p») ieiwes SOUND MENU
@ Mi... <TV MODE > = STEREO BILINGUAL
1~9,0... TEN KEY
-/ee ou 1 or 2 place
OS ee VIDEO INPUT (EXTERNAL INPUT SOURCE SW.)
Pa ener VOLUME
an ahdouts LEVEL PLUS (VOLUME, MENU)
oe ahve LEVEL MINUS (VOLUME, MENU)
) are UP (POSI., CH., TEXT PAGE)
WW enaa DOWN (POSI., CH., TEXT PAGE)
oO TXT/V....... TEXT, MIX, TV MODE SW.
Pea tee HOLD
O ree. | Qo <TEXT MODE > ....... REVEAL / CONCEAL
JIE") TEXT (ED eee < TEXT MODE > ....... F-T-B
C) (FULL, TOP, BOTTOM)
Lt
— © ~~ TEXT CLEAR (TEXT MODE)
FLOF COLOUR KEY (4 key used)
Red/Green/Yellow/Blue
OT esses Super woofer
Dud] ste Sound mode select
IIR cess Selectable picture
APR cee Selectable sound
MENU..... TUNING & OTHER MENU
@/@- Menu select
@/q@-: Level down/up
16:9... PIC SIZE (Picture size select)
VWaliHSoL
VTR control
(5 Power on/standby
> Play
H Stop
<<) Rewind
CT-9763 >> Fast forward

CIRCUIT BLOCK DIAGRAM
VY
TN-EG465LX1
MVGS44A
UR
TUNER IF/MPX
* *
*
AUDIO
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oS TA1218N
BAe 3 : e
)
AvVSW.
LY
(FULL)
|9
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P
avsw
[xe
TA1229N
° . re SECAM
2
COMB
-©)
jes
BRIER
TA1222AN
O° fe)
(2) |9 “4
21PIN |6 2 SAA5281ZP/E CHROMA
(S+AV)IE
0
RGB
VIDEO
oS
DEF.
©
RGB SW
iad
Cc El
ie
PROCESSOR ee |
Al
TA1217N
EXT SPK
*
PRO-LOGIC
UNIT
TA8211AH
TA8772AN +O ores}
1H | ieee: ‘ones ro] EXT SPK
DELAY “EXT/INT
HEAD PHONE SPK SW WOOFER
VIDEO OUT
12C
BUS
2804544
x3
©
TC74HC4053AP
ae
(FRONT)
p-CON
;
OSD
RGB
TA8427K
*
Ey
Ss
MEMORY
[_,]|
(3)
Vv
NM24CO04EN
TPM87CP38N-3228
TA8859AP
HV.
(REAR)
9
R
H.
OUT
+B VOLTAGE
2SD2253FA
F.B.T.
>
HYBRID
CONVERTER
TRANS.
STR-S6709
* PC BUS CONTROL

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 30 minutes 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.
HIGH VOLTAGE CHECK
CAUTION: There is no HIGH VOLTAGE ADJUST-
oe on this chassis.
. 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 32.0 kV.
4. Rotate the BRIGHTNESS Control to both extremes
to be sure the high voltage does not exceed the
limit of 32.0 kV under any conditions.
FOCUS ADJUSTMENT
Adjust FOCUS Control on FLYBACK TRANS. (1461)
for well defined scanning lines in the centre area on
the screen.,

SERVICE MODE GENERAL INSTRUCTIONS
1. ENTERING TO SERVICE MODE
1) Press “XK button once on 2) Press «K button again to 3) Keep pressing the *X button,
Remote Control. keep pressing. press MENU button on TV set.
RCUT Ss
32H
—_—_—_—_—— RR al
(Service mode display)
2. DISPLAYING THE ADJUSTMENT MENU
Press MENU button on TV.
Adjustment mode Service mode
RCUT Item
32H
Data
Press
we — E288
3. SELECTING THE ADJUSTING ITEMS
Every pressing of CHANNEL 4 button changes the adjustment items in the following order. (¥ button for reverse
order.)
4. ADJUSTING THE DATA
Pressing of VOLUME 4 or W button will change the value of data in the range from 00 to FF. The variable range
depends on the adjusting item.
5. EXIT FROM SERVICE MODE
Press POWER button to turn off the TV once.

OTHER SERVICE FUNCTION
The following key entry during display of adjustment menu provides special functions.
Remote Controller
CALL/ E) CAUTION! CALL/
Never try to perform
ad initialization unless you COI CALL ATTY
have
changed
the
OO’
O
A
Position up memory IC. LI G2) (sy
button on | | il
the TV set a (4) (5) (6) Ga
+ an =
(8) ‘a Reset th
Initialization
of
the
MEMORY
(QA02)
x
O
.
au
Sieh
pay
of
operating
protect
5 NS
B cut off
G
cut
off
O
OQ
fe)
0
(BCUT)
(GCUT) O e) OO
R cut off <1 -/+ Data adjusting
(RCUT)
Contrast correction
(CNTX)
Color thickness
correction
note: Displayed differently as
shown below, depending
on the setting of the
receiving color system.
COLP (PAL)
COLC (NTSC)
COLS (SECAM)
Test sound signal
ON/OFF (1 kHz)
( In TEST SIGNAL SELECTION )
mode operating. See next page.
Tint correction
(TNTC)
Self diagnosis
Test signal selection
Horizontal line
ON/OFF
a
Oo
on
=
03
>
Reset the count of operating
protect circuit
(Refer to the above.)
initialization of the MEMORY
(Refer to the above.)
{@ code. | babel
Service adjusting mode
Ye \\\ —
Service normal mode
(In service mode, ordinary
operations are possible.)
Sialic mle The adjusting item selection
~ 8-—

TEST SIGNAL SELECTION
Every pressing of -@) button changes the test patterns on screen as described below in SERVICE MODE.
Signal off —> NTSC signals (14 patterns)
PAL signals (14 patterns)
* About inside signal: The inside signal is output at video input terminal from QA01, and is not output with the pin
inserted into terminal. (Single color signal can be output.)
Signals Using method
Purity and White uniformity of CRT
* Red single color Red single color. . . . Stopping G and B output of Q501
* Green single color Green single color. . . . Stopping R and B output of Q501
* Blue single color Blue single color. . . . Stopping R and G output of Q501
* Black single color Black single color. . . . Making black signal of approx. 1Vp-p in QA01
* White single color White single color. . . . Making white signal of approx. 1Vp-p in QA01
* W/B adjustment White balance adjustment
White part. . . . White balance adjustment/check in light area
Black part. . .. White balance adjustment/check in dark area
>< Making approx. 1Vp-p signal in QA01.
* Black cross-bar Picture position (horizontal, vertical and slant) in CRT adjustment
* White cross-bar >< Making approx. 1Vp-p signal in QA01.
* Black cross-hatch Convergence and vertical amplitude adjustment
* White cross-hatch 3X Making approx. 1Vp-p signal in QA01.
* Black cross-dot Convergence adjustment
* White cross-dot a 3X Making approx. 1Vp-p signal in QA01.
* H signal For checking (of purity drift) of white uniformity of CRT
(Left, right, white) H signal (Left, right, white). . . . Check in light area
° H signal H signal (Left, right, black). . . . Check in dark area
(Left, right, black) The adjustment will be the best, if the time when unevenness of color in light
area occurs, is a little longer than that in dark area.
%% Making approx. 1Vp-p signal in QA01.

SERVICE MODE ADJUSTMENT
ITEM ADJUSTMENT PROCEDURE
INITIALIZATION OF QA02 After replacing QA02, the following initialization is required.
(MEMORY) 1. Call up the adjustment mode display following the steps 1 and 2 on page 7.
2. Press the CALL button on the Remote Control and CHANNEL A buttons on
the TV set simultaneously. The initialization of QA02 has been completed.
3. Check the picture carefully. If necessary, adjust any adjustment item.
Perform “AUTOMATIC SEARCH MEMORY’.
. Set CONTRAST to “00”, and
BRIGHTNESS to “50” by adjusting user
controls.
2. Set the TV in service mode to get white
cross-bar of inside pattern.
3. Select BRTC (brightness correction), and
adjust the 4 -/+ button to reduce the
value so that white portion of inside
pattern slightly light.
4. Adjust .4 -/+ button to increase the
data value of BRTC, and set it just
before the difference between the belt of
vertical retrace and the border of black
portion of inside pattern is visible.
After that, return vertical height and
contrast.
SUB-BRIGHTNESS
(Address : BRTC)
Note: Constrict the picture
height until the vertical
retrace line appears
adjusting the address HIT
(HEIGHT).
Belt of vertical retrace
HORIZONTAL POSITION
ADJUSTMENT (HPOS)
1. Set the TV in service mode, and get
black or white cross-bar signal with
VIDEO button on remote hand unit.
2. Select either HPOS (Horizontal
picture phase) or VPOS (Vertical
picture phase) with CHANNEL A, W
buttons, and adjust horizontal or
vertical picture position in the center
of screen with VOLUME .4 -/+
buttons.
VERTICAL POSITION
ADJUSTMENT (VPOS)
VERTICAL AMPLITUDE
ADJUSTMENT
(HIT)
1. Set the TV in service mode, and get
black or white cross-hatch signal with
VIDEO button on remote hand unit. The first ceHHH
2. Select HIT (Vertical amplitude) with Hoe
CHANNEL
A,
¥
buttons,
and
adjust
BERGE
vertical amplitude with VOLUME ZEEE
<1 —/+ buttons so that vertical
amplitude lacks a little.
3. Adjust vertical amplitude with VOLUME
<1 —/+ buttons so that the first bar on
cross-hatch signal touches edge of
screen.
~10-