Toshiba 28ZD26P User manual

– SUMMARY –
28ZD26P is the same as 32ZD26P except for the parts tabled on back of this sheet.
Use this service manual together with the original service manual of 32ZD26P (File No. 030-
200206).
FILE NO. 033-200221
SERVICE MANUAL
COLOUR TELEVISION
ZD26 Chassis
28ZD26P
PUBLISHED IN JAPAN, Jul., 2002 So

Location
No. Part No. Description
REPLACEMENT PARTS LIST DIFFERENCES
TOSHIBA CORPORATION
1-1, SHIBAURA 1-CHOME, MINATO-KU, TOKYO 105-8001, JAPAN
Location
No. Part No. Description
A201S 23530375 Front Cover
A223 23035412 Screw, BTB4X12SZN
A231 23445632 Button, Power
A242 23428087 Door
A401 23530271 Back Cover
A701 23064879 Carton
A702 23946384 Packing, Bottom
A703 23946385 Packing, Top
C314 24793101 EL, 100?F, ±20%, 10V
C315 24212102 CD, 1000pF, ±10%
C430 24820222 PF, 0.0022?F, 630V
C444 24503197 CF92T3Q622HA
C447 24820123 PF, 0.012?F, 630V
C491 24503190 CF92T2G124JA
C492 24503190 CF92T2G124JA
C4490 24503282 CF92T2G164JA
C4491 24503251 CF92T2G184JA
G306 24366562 CF, 5600 ohm
L441 23233035 Coil, Linearity, TLN2199AT
L901 23200489 Coil, Degaussing, TSB-2397CM
Q301 23905610 IC, LA7846N
Q304 23314794 Transistor, 2PC1815Y
R211 24366473 CF, 47k ohm
R227 24366333 CF, 33k ohm
R305 24323688 MF, 0.68 ohm, 2W
R311 24366911 CF, 910 ohm
R313 24366132 CF, 1300 ohm
R317 24366102 CF, 1k ohm
R321 24552392 OMF, 3900 ohm, 1/2W
R324 24366681 CF, 680 ohm
R325 24366103 CF, 10k ohm
R328 24366102 CF, 1k ohm
R336 24383221 OMF, 220 ohm, 2W
R353 24366471 CF, 470 ohm
R460 24366103 CF, 10k ohm
R461 23183966 TAS WIRE R60
R920 24000945 FR, 1.8 ohm, 2W
RA71X 24366683 CF, 68k ohm
RA72X 24366223 CF, 22k ohm
RA73X 24366103 CF, 10k ohm
RA76X 24366103 CF, 10k ohm
S801X 23344416 Switch, Power
SA01X 23145430 Switch, Push, 1C1P
SA02X 23145430 Switch, Push, 1C1P
SA03X 23145430 Switch, Push, 1C1P
SA04X 23145430 Switch, Push, 1C1P
SA05X 23145430 Switch, Push, 1C1P
T461 23236766 Transformer, Flyback,
TFB4188AH
T461B 23501175 Cable, Forcus
T461C 23501176 Cable, Forcus
*U901 23787341 CRT-D Board, PD0491C
*U902 23787342 SIGNAL Board, PD0492D
*U903A 23787343 POWER Board, PD0493D-1
*U903B 23787719 CONT-2 Board, PD0493D-2
*U903C 23787718 INDICATOR Board, PD0493D-3
*U904 23787344 DEF Board, PD0494D
V901 23312994 Picture Tube, W66QDE991X81
V901A 23903145 Socket, CRT

TOSHIBA CORPORATION
1-1, SHIBAURA 1- CHOME, MINATO-KU, TOKYO 105-8001, JAPAN
FILE NO. 030-200206
SERVICE MANUAL
COLOUR TELEVISION
ZD26 Chassis
32ZD26P
PUBLISHED IN JAPAN Mar. 2002 So

– 2 –
GENERAL ADJUSTMENTS
SPECIFIC INFORMATIONS
TABLE OF CONTENTS
CHAPTER 1 GENERAL ADJUSTMENTS
SAFETY INSTRUCTIONS ........................................................................................................................................ 3
SET-UP ADJUSTMENT ............................................................................................................................................ 4
SERVICE MODE ...................................................................................................................................................... 6
DESIGN MODE ........................................................................................................................................................ 9
ELECTRICAL ADJUSTMENTS .............................................................................................................................. 10
CIRCUIT CHECK .................................................................................................................................................... 12
CHAPTER 2 SPECIFIC INFORMATIONS
SETTING & ADJUSTING DATA .............................................................................................................................. 13
LOCATION OF CONTROLS ................................................................................................................................... 14
CHASSIS AND CABINET REPLACEMENT PARTS LIST ......................................................................................16
PC BOARDS BOTTOM VIEW................................................................................................................................. 29
TERMINAL VIEW OF TRANSISTORS ................................................................................................................... 37
CIRCUIT BLOCK DIAGRAM .................................................................................................................................. 40
SPECIFICATIONS .............................................................................................................................................. END
APPENDIX:
CIRCUIT DIAGRAM

–3 –
GENERAL ADJUSTMENTS
SPECIFIC INFORMATIONS
CHAPTER 1 GENERAL ADJUSTMENTS
SAFETY INSTRUCTIONS
WARNING: BEFORE SERVICING THIS CHASSIS, READ THE “X-RAY RADIATION PRECAUTION”, “SAFETY PRECAU-
TION”AND “PRODUCT SAFETY NOTICE”INSTRUCTIONS BELOW.
X-RAY RADIATION PRECAUTION
1. Excessive high voltage can produce potentially hazard-
ous X-RAY RADIATION. To avoid such hazards, the high
voltage must not be above the specified limit. The nominal
value of the high voltage of this receiver is (A) kV at zero
beam current (minimum brightness) under a (C) V AC power
source.The high voltage must not, under any circumstances,
exceed (B) kV.
Refer to table-1 for high voltage (A), (B) & AC voltage (C).
(See SETTING & ADJUSTING DATA on page 13)
Each time a receiver requires servicing, the high voltage
should be checked following the HIGH VOLTAGE CHECK
procedure in this manual. It is recommended that the read-
ing of the high voltage be recorded as a part of the service
record. It is important to use an accurate and reliable high
voltage meter.
2. The only source of X-RAY RADIATION in this TV receiver
is the picture tube. For continued X-RAY RADIATION pro-
tection, the replacement tube must be exactly the same
type tube as specified in the parts list.
3. Some part in this receiver have special safety-related char-
acteristics for X-RAY RADIATION protection. For contin-
ued safety, parts replacement should be undertaken only
after referring to the PRODUCT SAFETY NOTICE below.
SAFETY PRECAUTION
WARNING : Service should not be attempted by anyone unfamiliar with the necessary precautions on this receiver. The following
are the necessary precautions to be observed before servicing this chassis.
1. An isolation transformer should be connected in the power line between the receiver and the AC line before any service is
performed on the receiver.
2. Always discharge the picture tube anode to the CRT conductive coating before handling the picture tube. The picture tube
is highly evacuated and if broken, glass fragments will be violently expelled. Use shatter proof goggles and keep picture tube
away from the unprotected body while handling.
3. When replacing a chassis in the cabinet, always be certain that all the protective devices are put back in place, such as; non-
metallic control knobs, insulating covers, shields, isolation resistor-capacitor network etc.
PRODUCT SAFETY NOTICE
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These characteristics are
often passed unnoticed by a visual inspection and the protection afforded by them cannot necessarily be obtained by using
replacement components rated for higher voltage, wattage, etc. Replacement parts which have these special safety char-
acteristics are identified in this manual and its supplements; electrical components having such features are identified by
the international hazard symbols on the schematic diagram and the parts list.
Before replacing any of these components, read the parts list in this manual carefully. The use of substitute replacement
parts which do not have the same safety characteristics as specified in the parts list may create shock, fire, X-ray
radiation or other hazards.

–4 –
GENERAL ADJUSTMENTS
SPECIFIC INFORMATIONS
WARNING: BEFORE SERVICING THIS CHASSIS, READ THE “X-RAY RADIATION PRECAUTION”, “SAFETY PRECAU-
TION”AND “PRODUCT SAFETY NOTICE”ON PAGE 3 OF THIS MANUAL.
SET-UP ADJUSTMENT
■The following adjustments should be made when a complete realignment is required or a new picture tube is installed.
Perform the adjustments in order as follows :
1. Color Purity
2. Convergence
3. White Balance
Note: The PURITY/CONVERGENCE MAGNET assembly and rubber wedges need mechanical positioning.
Refer to figure 1.
Mounting position of the purity magnet assembly should fit to same position as old one because slightly difference to
the position depend on a kind of tube.
*There are no adjustment of purity and convergence in some picture tube (Unified with purity magnet)
GLASS CLOTH
TAPES
DEFLECTION
YOKE
TEMPORARY
MOUNTING
RUBBER WEDGE
ADHESIVE
DEFLECTION
YOKE
PURITY/
CONVERGENCE
MAGNET ASS'Y
29.1mm(28", 29")
25mm(25")
19mm(19", 20", 21")
14mm(13", 14")
Figure 1.
COLOR PURITY ADJUSTMENT
NOTE : Before attempting any purity adjustments, the receiver
should be operated for at least fifteen minutes.
1. Demagnetize the picture tube and cabinet using a degauss-
ing coil.
2. Set the brightness and contrast to maximum.
3. Use a green raster from among the built-in test signals.
4. Loosen the clamp screw holding the yoke and slide the
yoke backward or forward to provide vertical green belt
(zone) in the picture screen.
5. Remove the Rubber Wedges.
6. Rotate and spread the tabs of the purity magnet (See fig-
ure 2.) around the neck of the picture tube until the green
belt is in the center of the screen. At the same time, enter
the raster vertically.
7. Slowly move the yoke forward or backward until a uniform
green screen is obtained. Tighten the clamp screw of the
yoke temporarily.
8. Check the purity of the red and blue raster.

–5 –
GENERAL ADJUSTMENTS
SPECIFIC INFORMATIONS
CONVERGENCE ADJUSTMENTS
NOTE: Before attempting any convergence adjustments, the
receiver should be operated for at least fifteen min-
utes.
■CENTER CONVERGENCE ADJUSTMENT
1. Use the cross-dot pattern from among the built-in test sig-
nals.
2. Set the brightness and contrast for well defined pattern.
3. Adjust two tabs of the 4-Pole Magnets to change the an-
gle between them (See figure 2.) and superimpose red
and blue vertical lines in the center area of the picture
screen.
4. Turn the both tabs at the same time keeping the angle
constant to superimpose red and blue horizontal lines at
the center of the screen.
5. Adjust two tabs of 6-Pole Magnets to superimpose red/
blue line and green one. Adjusting the angle affects the
vertical lines and rotating both magnets affects the hori-
zontal lines.
6. Repeat adjustments 3, 4, 5 keeping in mind red, green
and blue movement, because 4-Pole Magnets and 6-Pole
Magnets have mutual interaction and make dot movement
complex.
■CIRCUMFERENCE CONVERGENCE ADJUSTMENT
1. Loosen the clamping screw of deflection yoke slightly to
allow the yoke to tilt.
2. Temporarily put a wedge as shown in figure 1. (Do not
remove cover paper on adhesive part of the wedge.)
3. Tilt front of the deflection yoke up or down to obtain better
convergence in circumference. (See figure 3.) Push the
mounted wedge into the space between picture tube and
the yoke to fix the yoke temporarily.
4. Put other wedge into bottom space and remove the cover
paper to stick.
5. Tilt front of the yoke right or left to obtain better conver-
gence in circumference. (See figure 3.)
6. Keep the yoke position and put another wedge in either
upper space. Remove cover paper and stick the wedge
on picture tube to fix the yoke.
7. Detach the temporarily mounted wedge and put it in an-
other upper space. Stick it on picture tube to fix the yoke.
8. After fixing three wedges, recheck overall convergence.
Tighten the screw firmly to fix the yoke and check the yoke
is firm.
9. Stick three adhesive tapes on wedges as shown in figure
1.
Figure 2.
BLU RED
BLU
RED
RED/BLU GRN
RED/BLU
GRN
B
G
R
R
G
B
BGR
RGB
BGR
RGB
R
G
B
B
G
R
4-POLE MAGNETS MOVEMENT
INCLINE THE YOKE UP (OR DOWN)
6-POLE MAGNETS MOVEMENT
Center Convergence by Convergence Magnets
Circumference Convergence by DEF Yoke
INCLINE THE YOKE RIGHT (OR LEFT)
Figure 3. Dot Movement Pattern
4-POLE
MAGNETS
PURITY
MAGNETS
6-POLE
MAGNETS
ADJUST THE ANGLE
(VERTICAL LINES) FIXED
ROTATE TWO TABS
AT THE SAME TIME
(HORIZONTAL LINES)
CONVERGENCE MAGNET ASSEMBLY ADJUSTMENT OF MAGNETS

–6 –
GENERAL ADJUSTMENTS
SPECIFIC INFORMATIONS
SERVICE MODE
1. ENTERING TO SERVICE MODE
S
(Service mode display)
Item
Data
Mute or
3) While pressing the obutton,
press MENU button on TV set.
2) Press obutton again to
keep pressing.
2. DISPLAYING THE ADJUSTMENT MENU
1) Press MENU button on TV.
3. KEY FUNCTION IN THE SERVICE MODE
The following key entry during display of adjustment menu provides special functions.
A single horizontal line ON/OFF: INFO button (on Remote) or abutton (on TV)
Test signal selection : abutton (on Remote)
Selection of the adjustment items : Channel s/t(on TV or Remote)
Change of the data value : Volume ;+/–(on TV or Remote)
Adjustment menu mode ON/OFF : MENU button (on TV)
Initialization of the memory (QA02) : CALL + Channel button on TV (s)
Reset the count of operating protect
circuit to “00”: CALL + Channel button on TV (t)
“RCUT”selection : 1 button
“GCUT”selection : 2 button
“BCUT”selection : 3 button
“CNTX”(or “SCNT”) selection : 4 button
“COLC”selection : 5 button
“TNTC”selection : 6 button
Self diagnostic display ON/OFF : 9 button
1) Press obutton once on
Remote Control.
Adjustment mode
Item
Data
Service mode
S
Press
Press
ITEM
DATA
Color thickness correction
note: Displayed differently as shown below, de-
pending on the setting of the receiving color
system.
COLP (PAL)
COLC (NTSC)
COLS (SECAM)
CAUTION : Never try to perform initialization unless you have changed the memory IC.

–7 –
GENERAL ADJUSTMENTS
SPECIFIC INFORMATIONS
4. SELECTING THE ADJUSTING ITEMS
1) Every pressing of CHANNEL sbutton in the service mode changes the adjustment items in the order of table-2.
(tbutton for reverse order)
Refer to table-2 for preset data of adjustment mode.
(See SETTING & ADJUSTING DATA on page 13)
5. ADJUSTING THE DATA
1) Pressing of VOLUME ;+/–button will change the value of data in the range from 00H to FFH. The variable
range depends on the adjusting item.
6. EXIT FROM SERVICE MODE
1) Pressing POWER button to turn off the TV once.
■INITIALIZATION OF MEMORY DATA OF QA02
After replacing QA02, the following initialization is required.
1. Enter the service mode, then select any register item.
2. Press and hold the CALL button on the Remote, then press the CHANNEL sbutton on the TV. The initialization of QA02 has
been complated.
3. Check the picture carefully. If necessary, adjust any adjustment item above.
Perform “Auto search Memory”on the owner’s manual.
CAUTION: Never attempt to initialize the data unless QA02 has been replaced.
7. TEST SIGNAL SELECTION
1) Every pressing of abutton on the Remote Control changes the built-in test patterns on screen as described below
in SERVICE MODE.
Signals Picture
•Red raster
•Green raster
•Blue raster
•All White
•Black cross-hatch
* The signals marked with are not usable to display in the Test signal for some model.
Signal off NTSC signals (5 patterns)
PAL signals (5 patterns)

–8 –
GENERAL ADJUSTMENTS
SPECIFIC INFORMATIONS
8. SELF DIAGNOSTIC FUNCTION
1) Press “9”button on Remote Control during display of adjustment menu in the service mode.
The diagnosis will begin to check if interface among IC’s are executed properly.
2) During diagnosis, the following displays are shown.
23******
POWER : 00
BUS LINE : OK
BUS CONT : OK
BLOCK :
UV V1 V2 V3
QV01
<SELF CHECK>
Part number of microcomputer (QA01)
Operation number of protecting circuit ----“00”is nor-
mal.
When indication is other than “00”, overcurrent apts to
flow, and circuit parts may possibly be damaged.
BUS LINE CHECK ----“OK”is normal.
“SDA1-GND”------------- SDA-GND short circuit.
“SCL1-GND”-------------- SCL-GND short circuit.
“SCL1-SDA1”------------- SCL-SDA short circuit.
BUS CONT ----“OK”is normal.
When indication shows “Q uuu NG”, the device with
the number may possibly be damaged.
BLOCK
UV : TV reception mode
V1 : VIDEO 1 input mode (a1)
V2 : VIDEO 2 input mode (a2)
V3 : VIDEO 3 input mode (a3)
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.
NOTE: Component which controls character display on
screen is ICF01 (TELETEXT IC.). If this display
function fails to operate due to damage in ICF01,
self diagnosis procedure is as follows.
(1) In case that power indicator is blinking with
interval of 0.5 seconds; it means protecting
circuit (Current limiter) is operating, and cir-
cuit components may possibly be damaged.
Check related components.
(2) In case that power indicator is blinking with
interval of 1 second; Protecting circuit does
not operate, but a part of Bus line does not
operate normally. Check Bus line.





* The items marked with are not usable to display in the SELF DIAGNOSTIC FUCTION for some model.