Toshiba 2550TB Schematic

TOSHIBA 2550 TB

General Information

C4E-R Chassis

Recommended Safety Parts

Item Part No. Description

C440 24082583 PF, 7200pF, ±3%, 1500V
C441 24214221 CD, 220pF, ±10%, 500V
C443 24214221 CD, 220pF, ±10%, 500V
C444 24082517 PF, 5100pF, ±3%, 1800V
C463 24212222 CD, 2200pF, ±10%
C801 24082363 PF, 0.22µF, ±20%, AC250V
C802 24094656 CD, 2200pF, ±20%, AC400V
C803 24094656 CD, 2200pF, ±20%, AC400V
C807 24092281 CD, 4700pF, ±20%, AC250V
C808 24092281 CD, 4700pF, ±20%, AC250V
L462 ———— DY, Supplied with V901
L901 23200275 Coil, Degaussing, TSB-2329BR
T461 23236454 Transformer, Flyback, TFB4117AR
Q404 A6872801 Transistor, 2SD2253(FA)
F801 23144898 Fuse, 3.15A
F803 23144874 Fuse, 0.8A
P801 23372012 Power Cord
S801 23145434 Switch, Power, 2C2P
V901A 23902891 Socket, CRT, 10P
ZP30 23144450 Protector, PRF2000, 125V, 2A
ZP40 23144451 Protector, PRF5000, 125V, 5A
ZP80 23144450 Protector, PRF2000, 125V, 2A
ZP90 23144452 Protector, PRF1000, 125V, 1A
V901 23312643 Picture Tube, A59TMZ40X06

X-Ray Note

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 26.3 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 27.5 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.

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.

GENERAL INFORMATION

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
240 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 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. If colour
shading still persists, perform the COLOUR
PURITY ADJUSTMENT and CONVERGENCE
ADJUSTMENTS procedures.

HIGH VOLTAGE CHECK
CAUTION: There is no HIGH VOLTAGE

ADJUSTMENT 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 27.5 kV.

4. Rotate the BRIGHTNESS Control to both
extremes to be sure the high voltage does not
exceed the limit of 27.5 kV under any
conditions.

HORIZONTAL CENTRE ADJUSTMENT

1. Receive the WG PHILIPS pattern, and set the
contrast and colour to minimum, and the
brightness to centre.

2. Adjust HEIGHT Control (R351) so that white
blocks at top and bottom of the picture are
just masked.

FOCUS ADJUSTMENT

Adjust FOCUS Control on FLYBACK TRANS.
(T461) for well defined scanning lines in the
centre area on the screen.

1. Receive the WG PHILIPS pattern.

2. Set the contrast and colour to minimum, and
the brightness to centre.

3. Adjust H. CENTER SUB Control (R451) so
the pattern can be located for d-c to be + 4.0
mm.

FOCUS ADJUSTMENT

Adjust FOCUS Control on FLYBACK TRANS.
(T461) for well defined scanning lines in the
centre area on the screen.

DELAYED R-F AGC ADJUSTMENT

1. Tune the set in the strongest station in your
area.

2. Turn AGC DELAY Control (R151) on MAIN
Board to fully counterclockwise position.

3. Adjust AGC DELAY Control clockwise until
noise (snow) disappears on the screen.

CRT GREY SCALE ADJUSTMENT

1. Press VIDEO INPUT button on Remote
Control unit to turn TV to video input mode.
(Video input should have no signal.) Next
press PICTURE SELECT button to select
function and set CONTRAST to minimum,
BRIGHTNESS to maximum, COLOUR to
minimum.

2.Turn the SCREEN Control (on T461) fuly
counterclockwise.

3. Set the RED, GREEN and BLUE CUT OFF
Controls (R557, R558, R559)
counterclockwise to the centre position.

4. Set the GREEN and BLUE DRIVE Controls
(R252, R253) to the centre position.

5. Set the CUT OFF SW. (S202) in the H. line
position.

6. Set the SUB BRIGHTNESS Control to
minimum.

7. Rotate the SCREEN Control gradually
clockwise until the first horizontal line of a
colour (RED, GREEN or BLUE) appears
slightly on the screen. Set the SCREEN
Control to this position.

8. 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.

9. Return the CUT OFF SW. (5202) in the
receiving position. Press VIDEO INPUT
button to turn TV to the TV mode.

10.Set the BRIGHTNESS Control to the
maximum and COLOUR Control to the centre.

11.Adjust the BLUE and GREEN DRIVE
Controls (R252/R253) to obtain proper white­balanced picture in high light areas.

12.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. Tune in a colour programme of Philips
pattern.

2. Set the CONTRAST Control to the minimum
and the BRIGHTNESS Control to the centre.

3. Set the COLOUR Control to the minimum.

4. Set the SUB-BRIGHT. Control (R551) so that
the voltage across terminals Y-Z can be 0.2 +

0.05V with voltmeter and leave the receiver
for five minutes in this state.

5. Watching the picture well, adjust the SUB­BRIGHT. 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.

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 the SUB-BRIGHT. Control again for the
acceptable picture.

1. In the TV set of initial lot of production,
SAA5290ZP/024 is used for QA01. But
replace with SAA5290ZP/032 for servicing.

2. When QA01 only is replaced, it is not
necessary to change the mode data.

3. When memory IC (QA02) is replaced, change
the mode data in the manner below.

1. OUTLINE

In the service mode, MODE DATA adjustments
can be made easily with user remote control
unit. (CT-9689 only)

2. SERVICE MODE OPERATION

2-1. How to Enter the Service Mode

2-2. How to Exit from the Service Mode

Exit the service mode by turning the power on/
off with the remote control.

3. ADJUSTMENT IN THE SERVICE MODE

Service Mode Level Adjustments

1) Push F + key (simultaneous push) to
Mode Data to be adjusted.

2) Adjust with the level UP/DOWN (VOL UP/
DOWN key) key.

Example of screen display in level adjust­ment.

GENERAL: Refer to figure 4 for test equipment
connection.
PRELIMINARY STEPS: Supply +5 volts to the
5V-1 line.
SIGNAL GENERATOR: Connect to both leads of
R101 with signal level of 75 dBµ, and open the
solder-link at IF OUT of tuner on the Main
Board. (See figure 4.)
DVM Connect to pin #44 of IC501 on the Main
Board through the detector.

Figure 4. Picture IF Alignment
STEP

Detector Coil

SIGNAL GENERATOR

39.5 MHz CARRIER WAVE (Level 75 dBµ)

ADJUST

T103

REMARKS

1. Supply external DC power (+ 5V) to 5V-1 line.

2. Supply + 8V to pin 36 of 1C501.

3. Supply external DC power to + 12V line.

4. Apply test signal to IF input.

5. Adjust T103 so that DC voltage at pin 44 of
IC501 becomes 3.2V ± 0.5V. After completing
the above steps, disconnect the equipment
and re-solder the liniks on the Main Board,
and adjust the AGC Delay Control (R151)
following DELAYED RF AGC ADJUST­MENTS.