Toshiba 2857DB Schematic

TOSHIBA 2857 DB

1

General Information

Chassis: C5SS

Matrix

Item See Model Book

Adjustments (Not Service mode) ..................................................................2152 DB 5

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 31.5 kV at zero beam
current (minimum brightness) operating at
240V 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, 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.

3. 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

1. 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.

4. Replace blown fuses within the receiver with
the fuse specified in the parts list.

5. 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.

6. Keep wires away from high temperature
components.

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, etc. 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 X­ray radiation.

Recommended Safety Parts

Item Part No. Description

A401 23426393 Back Cover
C440 24082482 PF, 7000pF, ±3%, 1500V
C441 24082669 PF, 0.33µF, 250V
C442 24082672 PF, 0.43µF, 250V
C444 24082519 PF, 6200pF, ±3%, 1800V
C463 24212222 CD, 2200pF, ±10%
C801 24082374 PE, 0.22µF , AC250V
C805 24092281 CD, 4700pF, ±20%, AC250V
C806 24092281 CD, 4700pF, ±20%, AC250V
R801 24009954 Metal-Glazed Resistor, 2.2M ohm, 1/2W
R808 24019340 PTC Thermistor, 18 ohm, 290V
R810 24007489 Cement, 3 ohm, 20W
R811 24568271 Cement, 270 ohm, 7W
R824 24569689 Cement, 6.8 ohm, 10W
R841 24531120 FR, 12 ohm, 1/2W
R899 24005007 Metal-Glazed Resistor, 8.2M ohm, 1W
L462 ------------- DY, Supplied with V901
L901 23200276 Coil, Degaussing, TSB-2330BR
T401 23224336 Transformer, Horiz. Drive, TLN1083
T461 23236447 Transformer, Flyback, TFB4115AR
T801 23211891 Line Filter, TRF3164
T803 23217301 Transformer, Converter, TPW3336AR
Q404 A6872801 Transistor, 2SD2253(FA)
Q801 23905084 IC, STR-S6709
Q826 A8643106 Photo Coupler, TLP621(GR)
D801 23316795 Diode, D6SB60L,F05
F470 23144873 Fuse, 1.0A
F801 23144898 Fuse, 3.15A
P801 23372012 Power Cord
V901A 23902891 Socket, CRT, 10P
V901 23312645 Picture Tube, A66EAK252X21

Service Mode General

Instructions

1. ENTERING TO SERVICE MODE

1) Press button once on Remote Control.

2) Press button again to keep pressing.

3) Keep pressing the button, press MENU
button on TV set.

RCUT S
32H

(Service mode dIsplay)

2. SELECTING THE ADJUSTING ITEMS

Every pressing of CHANNEL ▲ button changes
the adjustment items in the following order.
(▼ button for reverse order.)

3. ADJUSTING THE DATA

Pressing of VOLUME ▲ or ▼ button will change
the value of data in the range from 00 to FF. The
variable range depends on the adjusting item.

4. NORMAL OPERATION ON THE SERVICE
MODE

Press MENU button on TV.

Adjustment mode Service mode

RCUT Address S

➤

➤

32H Data

5. EXIT FROM SERVICE MODE

Press POWER button on the remote control to
turn off the TV once.

OTHER SERVICE FUNCTION

The following key entry during display of
adjustment menu provides special functions.

Press

Press

➤

➤

➤

➤

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

Red single colour
Green single colour
Blue single colour
Black single colour
White single colour

Picture

Using method

Purity and White uniformity of CRT
Red single colour.

➜

➜

➜

Stopping G and B output of Q501
Green single colour.
Stopping R and B output of Q501
Blue single colour.
Stopping R and G output of Q501
Black single colour.
Making black signal of approx. 1Vp-p in QA01
White single colour.
Making white signal of approx. 1Vp-p in QA01

Signals

W/B adjustment

Picture

Using method

White balance adjustment
White .
White balance adjustment/check in light area
Black part.
White balance adjustment/check in dark area.
Making. approx. 1Vp-p signal in QA01.

Signals

Black cross-bar
White cross-bar

Picture

Using method

Picture position (horizontal, vertical and slant) in
CRT adjustment.
Making approx. 1 Vp-p signal in QA01.

Signals

Black cross-hatch
White cross-hatch

Picture

Using method

Convergence and vertical amplitude adjustment
Making approx. 1 Vp-p signal in QA01.

Signals

Black cross-dot
White cross-dot

Picture

Using method

Convergence adjustment
Making approx. 1Vp-p signal in QA01.

Signals

H signal (Left, right, white)
H signal (Left, right, black)

Picture

Using method

For checking (of purity drift) of white uniformity
of CRT H signal (Left, right, white).
Check in light area.
H signal (Left, right, black).
Check in dark area.
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.

TOSHIBA 2857 DB

2

Service Mode Cont’d

ITEM:

Initialisation of QA02 (Memory)

ADJUSTMENT PROCEDURE:

After replacing QA02, the following initialisation
is required.

1. Call up the adjustment mode display following
the steps 1 and 2.

2. Press the CALL button on the Remote Control
and CHANNEL ▲ buttons on the TV set
simultaneously. The initialisation of QA02 has
been completed.

3. Check the picture carefully. If necessary,
adjust any adjustment item.

Perform “AUTOMATIC SEARCH MEMORY”
ITEM: SUB-BRIGHTNESS (Address: BRTC)
Note: Constrict the picture height until the

vertical retrace line appears adjusting the
address HIT (HEIGHT).

ADJUSTMENT PROCEDURE:

1. Set CONTRAST to “00,, and BRIGHTNESS to
“50” by adjusting user controls.

2. Set the TV in service mode to get white cross­bar of inside pattern.

3. Select BRTC (brightness correction), and
adjust the - / + button to reduce the value

so that white portion of inside pattern slightly
light.

4. Adjust - / + 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.

ITEMS:

HORIZONTAL POSITION ADJUSTMENT
(HPOS)

VERTICAL POSITION ADJUSTMENT (VPOS)

ADJUSTMENT PROCEDURE:

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 ▲, ▼ buttons, and adjust horizon­tal or vertical picture position in the center of

screen with VOLUME - / + buttons.

ADJUSTMENT PROCEDURE:

1. Set the TV in service mode, and get black or
white cross-hatch signal with VIDEO button
on remote hand unit.

2. Select HIT (Vertical amplitude) with CHAN­NEL ▲, ▼ buttons, and adjust vertical

amplitude with VOLUME - / + buttons so
that vertical amplitude lacks a little.

3. Adjust vertical amplitude with VOLUME - /
+ buttons so that the first bar on cross-hatch
signal touches edge of screen.

WHITE BALANCE ADJUSTMENT
CUTOFF ADJUSTMENT

(RCUT)
(GCUT)
(BCUT)

DRIVE ADJUSTMENT

(GDRV)
(BDRV)

1. Set Contrast to 40, and brightness to +20 by
picture control.

2. Set the TV in service mode, and get the inside
W/B adjusting signal with VIDEO button.

3. Select RCUT, GCUT and BCUT with CHAN­NEL ▲, ▼ buttons, to set individual values to
32, and to set GDRV and BDRV to 20 with

VOLUME - / + buttons.

4. Press button on the remote control and
rotate Screen VR to get one slight horizontal
line on screen.
Note:Every pressing of button provides
Horizontal line picture and Normal picture
alternately.

5. Press button to release horizontal line
picture, and select the two other colors which
did not light in the above step with CHANNEL

▲,▼ buttons. Then tap VOLUME - / +
buttons so that three colors slightly light in the
same level.

To correct white balance in light area, select
GDRV and BDRV with CHANNEL ▲,▼ buttons
to adjust.

To correct white balance in dark area, perform
fine adjustment of RCUT, GCUT and BCUT.

Light area check (to show white)

Dark area check (to show black)

1) Part number of microcomputer (QA01)

2) Operation number of protecting circuit ----“00”
is normal. When indication is other than “00”,
overcurrent apts to flow, and circuit parts may
possibly be damaged.

3) BUS LINE CHECK ---- “OK” is normal.
“SDA1-GND” means that SDA line is shorted
to ground.
“SCL1-GND” means that SCL line is shorted
to ground.
“SCL1-SDA1” means that SDA line is shorted
to SCL line.

4) BUS CONT----“OK” is normal.
When indication shows “Q OOO NG”, the
device with the number may possibly be
damaged.

5) BLOCK

UV : TV reception mode
V1: VIDEO 1 input mode ( 1)
V2 :VIDEO 2 input mode ( 2)

➜

➜

Indicated color of mode now selected: Green
and Red
Indicated color of other modes: White
Green: Normal
Red: The microcomputer operates to provide
judgement of no video signal. The red color is
still indicated though the signal is input, failure
may exist in input signal line including QV01.
QV01: In case of indication green --- Normal
In case of indication red with input signal ---­Failure may exist in output line including QV01.

Sub Data Additional Description

Symbol Description

HPOS H screen position correction

HIT V amplitude adjustment.

Item Name Setting(User control) Input signal Measurement point Adjustment procedure Adjustment standard

[COLP] SUB Contrast: MAX Sub-bright IC501 1. Select slave address OCH 1.35V(p-p)

[RCUT] R cut-off RCUT 40 Hexa-decimal Screen 1. Set the controls as shown in
[GCUT] G cut-off GCUT 40 Hexa-decimal adjustment the left column.
[BCUT] B cut-off BCUT 40 Hexa-decimal 2. Gradually increase the screen
Screen VR Screen GDRV 40 Hexa-decimal VR (T461) until one of R, G or BDRV B line begins

[RCUT] R cut-off Contrast: MAX White, etc. Screen 1. This adjustment must be done HIGH LIGHT;
[GCUT] G cut-off Bright : CENTER adjustment after adjustment of the above- (103cd/m3)
[BCUT] B cut-off Color : CENTER mentioned cut-off and screen 7195K
[GDRV] C drive VR’s have been completed. -0.005uv [BDRV]
[BDRV] B drive 2. Adjust cut-off and drive DATA DARK;

Model name: C5SS (2857DB/3357DB)

Adjustment parts or Input point/ Adjustment signal Adjustment conditions and procedures
Bus control item Output point

Horizontal amplitude Visual check of picture WG Philips pattern 1. Conditions: After V. HEIGHT, VERT POSITION
adjustment (WID) (Bus control) and H. CENT have been adjusted, set
Pin distortion Do not use the Philips the controllers as follows:
compensation amount pattern of Contrast: MAX
adjustment (PARA) FRANCESECAM. Brightness: Center
Keystone distortion Color: Center
compensation amount 2. Adjustment procedure
adjustment (HOP) a. Adjust the horizontal amplitude by the sub address WID.

Symbol Description

VSC V linearity correction 2.

COLOUR Bright: CENTER signal #55 [COLP]. ± 0.2V(p-p)
PAL Color: CENTER (PAL) (TP501) 2. When [COLP] is selected, Y-signal is muted

Select horizontal line mode by to brighten slightly.
pressing

-I-

control in service mode. 4. Adjust RCUT, GCUT and BCUT, brighten other lines

(White alternately. (17cd/m3)
balance) 3. Use a checker to adjust 7695K ± 0uv

- button on the remote 3. Determine the position of the screen VR here.

Symbol Description

PARA H pin-cushion distortion

correction.

and only color signals are outputted.

3. Adjust amplitude of the upper half of the colour
bar output.

until they begin to light slightly.
(Adjust DATA so that the line becomes almost white.)

5. Press

-I-

horizontal line mode.

brightness by changing modulation factor.

Adjust so that the left and right white flags of
Philips pattern disappear at the very limits.
b. Make the left and right vertical bars straight by the sub address PARA.
c. Compensate the key distortion by the sub address HOP.
d. Again, adjust the sub address WID.

- button on the remote control to escape from the

Symbol Description

HCP Setting of amount of H amplitude

correction against variation of
screen brightness.

VFC V linearity correction.

Linearity balance at 1/4, 3/4
areas from top.

Linearity balance between top/
bottom and center.

CNR H pin-cushion distortion

VPOS VPS V picture position adjustment

correction at four corners.

ITEM:

VERTICAL AMPLITUDE ADJUSTMENT (HIT)

SELF DIAGNOSTIC FUNCTION

1) Press “9” button on Remote Control during
display of adjustment menu. The diagnosis
will begin to check if interface among IC’s are
executed properly.

2) During diagnosis, the following displays are
shown.

(SELF CHECK)
(1) 2390XXXX
(2) POWER : 00
(3) BUS LINE : OK
(4) Bus CONT : OK
(5) BLOCK : UV V1 V2

QV01

LIN V linearity correction 1.

Linearity balance between top
and bottom screen.

VCP Setting of amount of V amplitude

correction against variation of
screen brightness.

WID H amplitude adjustment.

TRAP Pedestal distortion correction.

TOSHIBA 2857 DB

3

Service Mode Cont’d

MULTI BUS E2PROM ADDRESS, ADJUSTING ADDRESS TABLE

Adjusting 0A02 Name Value of Initializing
method memory of QA02 Adjustments

address item (Hexa-decimal)

F 03H RCUT 40H R OUTOFF (B/W)

04H GCUT 40H G OUTOFF (B/W)
O5H BCUT 40H B OUTOFF (B,W)
06H GDRV 40H G DRIVE

➤

07H BDRV 40H B DRIVE
S 08H CNTX 7FH SUB CONTRAST MAX (4:3 MODE)
F 09H BRTC 7FH SUB BRIGHT CEN

0AH COLC 50H SUB COLOR CEN NTSC

BH TNTC 40H SUB TINT CEN

0CH COLP 50H SUB COLOR CEN PAL

➤

0DH COLS 50H SUB COLOR CEN SECAM
S 0EH SCOL 8FH SUB COLOR

0FH SCNT 7FH SUB CONTRAST

25H VOLS 00H VOL SCART

26H FVOL 00H FM VOL PRE SCALE

27H NVOL 00H NICAM VOL PRE SCALE

28H NICL 00H NICAM THRESHOLD LEVEL

29H NICH 00H NICAM THRESHOLD LEVEL

2AH IDL 00H IGR THRESHOLD LEVEL

2BH IDH 00H IGR THRESHOLD LEVEL

20H EVOL 00H EXT PRE. VOLUME

2DH EMX FCH NICAM ON LEVEL

2EH EMN 64H NICAM OFF LEVEL

2FH FMA 00H FM ATTENUATOR LEVEL

➤

30H STS 00H STEREO SEPARATION
F 31H HPOS 15H 50Hz H-POSITION

32H VPOS 04H V-POSITION

33H HIT 3EH HEIGHT

37H VLIN 11H V-LINEARITY

38H VSC 0FH V-S CORRECTION

39H VPS 0EH V-SHIFT

➤

3AH VCP 06H V-COMPENSATION
F 3BH WID 0FH PICTURE WIDTH
F 30H PARA 2AH E-W PARABOLA
S 3DH CNR 0GH E-W CORNER

3EH TRAP 1FH TRAPEZIUM

3FH HCP 02H H-COMPENSATION

40H VFC 0EH V-F CORRECTION

C9H BELL 00H SECAM BELL FILTER

CAH SRY 08H SECAM R-Y

➤

CBH SBY 08H SECAM B-Y

CRT PCB Diagram

S... semi-fixed data area which is fixed by model. (Do not adjust in field service.)
F... This item may require adjustments by models after initialization, when QA02 is replaced