Toshiba 31HX83 Service Manual

FILE NO. 070-200333

DOCUMENT CREATED IN JAPAN, Jan., 2004

SERVICE MANUAL

COLOR TELEVISION

N3WS Chassis

34HX83

(TAC0321)

CHAPTER 1 GENERAL ADJUSTMENTS

SAFETY INSTRUCTIONS ........................................................................................................................................ 3

SET-UP ADJUSTMENT ............................................................................................................................................ 4

SERVICE MODE ...................................................................................................................................................... 6

ELECTRICAL ADJUSTMENTS ................................................................................................................................ 9

CIRCUIT CHECKS ................................................................................................................................................. 11

CHAPTER 2 SPECIFIC INFORMATIONS

GENERAL ADJUSTMENTS

SETTING & ADJUSTING DATA .............................................................................................................................. 12

LOCATION OF CONTROLS ................................................................................................................................... 13

ADDING CHANNELS TO THE TV'S MEMORY ...................................................................................................... 15

CHASSIS AND CABINET REPLACEMENT PARTS LIST ......................................................................................16

PC BOARDS BOTTOM VIEW................................................................................................................................. 31

TERMINAL VIEW OF TRANSISTORS ................................................................................................................... 40

CIRCUIT BLOCK DIAGRAM .................................................................................................................................. 42

SPECIFICATIONS .............................................................................................................................................. END

TABLE OF CONTENTS

APPENDIX:

CIRCUIT DIAGRAM

– 2 –

CHAPTER 1 GENERAL ADJUSTMENTS

AC VOLTMETER

0.15µF

Good earth ground
such as a water
pipe, conduit, etc.

Place this probe on
each exposed
metallic part.

1500 ohm
10 watt

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 hazardous
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 120V AC
power source. The high voltage must not, under any cir­cumstances, exceed (B) kV.

Refer to table-1 for high voltage (A), (B).
(See SETTING & ADJUSTING DATA on page 12)

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 read­ing 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.

SAFETY PRECAUTION

2. This receiver is equipped with a Fail Safe (FS) circuit which
prevents the receiver from producing an excessively high
voltage even if the B+ voltage increases abnormally. Each
time the receiver is serviced, the FS circuit must be checked
to determine that the circuit is properly functioning, follow­ing the FS CIRCUIT CHECK procedure in this manual.

3. The only source of X-RAY RADIATION in this TV receiver
is the picture tube. For continued X-RAY RADIATION pro­tection, the replacement tube must be exactly the same
type tube as specified in the parts list.

4. Some part in this receiver have special safety-related char­acteristics for X-RAY RADIATION protection. For contin­ued safety, parts replacement should be undertaken only
after referring to the PRODUCT SAFETY NOTICE below.

GENERAL ADJUSTMENTS

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.

4. Before returning the set to the customer, always perform
an AC leakage current check on the exposed metallic parts
of the cabinet, such as antennas, terminals, screwheads,
metal overlays, control shafts etc. to be sure the set is
safe to operate without danger of electrical shock. Plug
the AC line cord directly into a 120V AC outlet (do not use
a line isolation transformer during this check). Use an AC
voltmeter having 5000 ohms per volt or more sensitivity in
the following manner:

Connect a 1500 ohm 10 watt resistor, paralleled by a 0.15
µF, AC type capacitor, between a known good earth ground
(water pipe, conduit, etc.) and the exposed metallic parts,
one at a time. Measure the AC voltage across the combi­nation of 1500 ohm resistor and 0.15 µF capacitor. Re­verse the AC plug at the AC outlet and repeat AC voltage
measurements for each exposed metallic part. Voltage
measured must not exceed 0.3 volts rms. This corresponds
to 0.2 milliamp. AC. Any value exceeding this limit consti­tutes a potential shock hazard and must be corrected im­mediately.

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 charac­teristics 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.

PRODUCT SAFETY NOTICE

– 3 –

WARNING: BEFORE SERVICING THIS CHASSIS, READ THE “X-RAY RADIATION PRECAUTION”, “SAFETY PRECAU-

TION” AND “PRODUCT SAFETY NOTICE” ON PAGE 3 OF SERVICE MANUAL.

■ 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.

COLOR PURITY ADUSTMENT

GENERAL ADJUSTMENTS

(1)Let the screen face in the installing direction or toward the east (when it is to be moved), bring up the service mode

screen after demagnetizing (front, left, right, and top) with the degaussing coil, receive white signals by pressing the
[TV/VIDEO] button, and then the receiver should be operated for more than 40 minutes.

(2)Perform rough adjustment of the central convergence with the P/C magnet according to the adjustment item.

(3)Receive built-in green signals, loosen set screws on the deflection yoke, remove rubber wedges, and shift the deflection

yoke to toward front.

(4)Move alternately the two 2-pole magnets of the P/C magnets so that the green raster can come to the center of the

screen.

SET-UP ADJUSTMENT FOR FLAT TUBE

Figure 1.

2-pole purity magnet

(27": Magnet is fixed with deflection yoke.)

Green Belt

Sub-4-pole convergence magnet (32" : 34")
Sub-4-pole convergence magnet (to be installed on deflection yoke for 30", 32”)

Main 4-pole convergence magnet (30" : 32")
6-pole convergence magnet (34")
6-pole convergence magnet (30" : 32")
Main 4-pole convergence magnet (34")

P/C magnet installing position A

• 30"=26.5 mm

A

• 32"=30.5 mm or 32.5 mm

• 34"=37 mm

• 34"=39 mm

(5)Receive built-in red and blue signals, check that there is no inclination of the single color raster toward one side, and if

each color tilts to a great extent, make adjustment with the 2-pole magnet so that the 3 colors will come to the center
evenly.

(6)Receive the green raster, shift the deflection yoke from a

foremost position (hitting against the picture tube) to a

Shift deflection yoke

(7) Perform marking of each point on

(6)

(8)

the tape of picture tube

backward position horizontally, stop the deflection yoke
at a position where it begins to become a green raster,
and perform accurate marking on the picture tube.

(7)Shift the deflection yoke further backward, and perform

Picture tube

CRT-D board

accurate marking at a position where the green raster
begins to being luck.

(8)Fix the deflection yoke at a position 60% forward within

the range marked in items (6) and (7) above.

CONVERGENCE ADJUSTMENTS

100 60 0%

Fix the deflection yoke at a position 60% forward from a point
between (6) and (7)

P/C Mag

* Adjust the convergence magnet to get vest convergence in the the order to (1) ~ (5).

■ CENTER CONVERGENCE:

(1)Receive the white crosshatch or dot pattern from the service signal generator.

(2)Use the 2 pieces of main 4-pole magnets of P/C magnets, change the open angle, and align the red and blue vertical

lines on the screen center.

(3)Freeze the open angle of the main 4-pole magnets, turn them simultaneously, and align the horizontal lines.

(4)Take the same steps for items (2) and (3) above and align red/blue with green on the screen center using two 6-pole

magnets.

– 4 –

(5)Adjust the sub-4-pole magnets only in case there is any deviation of Xv bow-shaped convergence. (To be usually set at

the initial position)

Align both sides with the sub-4-pole magnets and minimize the deviation of blue and red with the main 4-pole magnets.

blue

blue
red

red

Main 4-pole magnet

red/blue

red/blue

green

6-pole magnet

■ CIRCUMFERENCE CONVERGENCE:

Perform correction in the following manner.

*

blue

green
red

A

B

C

(Parts code:23 948 274) TC-S

blue

green

red

S
N

Blue color or blue mark

D

E

F

*Insert the correction piece between the
picture tube and the deflection yoke.

Bonded surface

(Insertion position of correction
piece)

D

E

F

A

B

C

Adjust VR 1 and minimize the deviation of YH. *Only 27", 30" and 32".

Red

green

blue

blue

green

Red

Xv bow-shaped deviation of convergence

blue

green

red

Sub-4-pole magnet

• Adjust coils and minimize deviation
(The 27” unit has coils underneath it)

A

B

C

■ 30", 27", 32"

blue

green

red

(Parts code:23 948 464)

N
S

Transparent

GENERAL ADJUSTMENTS

D

E

F

Bonded surface

Red

green

blue

blue

green

Red

Adjust VR 2 (YHC) and minimize the deviation of YH.

Red

blue

green

green

blue

Red

blue

Red

green

green

Red

blue

Adjust VR 3 (YV) and minimize the deviation of YV.

Red

green

blue

blue

green

Red

GH

Red

blue

green

green

blue

red

green

blue

red

green

green

Red

– 5 –

blue

Red

Red

blue

blue

green

VR3

VR2 VR1

■ 34"

YV YHC

27" (Part No. 23 947 371)
32", 30" (Part No. 23 947 121)
34" (Part No. 23 993 080)

GH

Perform correction by inserting the

correction piece into the clear­ance of terminal board coils of
the deflection yoke.

Note:

Perform insertion by turning the

metal side to the terminal board
side of the deflection yoke.

1. ENTERING TO SERVICE MODE

1) Press MUTE button twice
on Remote Control.

SERVICE MODE

2) Press MUTE button
again to keep pressing.

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

S

1/2 MUTE

GENERAL ADJUSTMENTS

2. DISPLAYING THE ADJUSTMENT MENU

1) Press MENU button on TV.

Service mode

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: TV (ANT)/VIDEO button (on TV)
Test signal selection : TV (ANT)/VIDEO button (on Remote)
Selection of the adjustment items : Channel s/t (on TV or Remote)
Change of the data value : Volume s/t (on TV or Remote)
Adjustment menu mode ON/OFF : MENU button (on TV)
Initialization of the memory (QA02, QA04) : RECALL+Channel (s) button on TV
Initialization of the self diagnostic data: RECALL+Channel (t) button on TV

“RCUT” selection : 1 button
“GCUT” selection : 2 button
“BCUT” selection : 3 button
“CNTX” selection : 4 button
“COLC” selection : 5 button
“TNTC” selection : 6 button

Test audio signal ON/OFF (1kHz) : 8 button
Self diagnostic display ON/OFF : 9 button

MUTE

(Service mode display)

Adjustment mode

S

Press

Press

Item

Data

– 6 –

4. SELECTING THE ADJUSTING ITEMS

1) Every pressing of CHANNEL s button in the service mode changes the adjustment items in the order of table-2.
(t button for reverse order)

Refer to table-2 for preset data of adjustment mode.
(See SETTING & ADJUSTING DATA on page 12)

5. ADJUSTING THE DATA

1) Pressing of VOLUME s or t button will cahnge 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 AND QA04

After replacing QA02 and QA04, the following initialization is required.

1. Enter the service mode, then select any register item.

2. Press and hold the RECALL button on the Remote, then press the CHANNEL s button on the TV. The initialization of QA02
and QA04 has been complated.

3. Check the picture carefully. If necessary, adjust any adjustment item above.
Perform “Programming Channel Memory” on the owner's manual.

CAUTION: Never attempt to initialize the data unless QA02, QA04 has been replaced.

7. TEST SIGNAL SELECTION

1) Every pressing of TV/VIDEO button on the Remote Control in the Service mode changes the built-in test patterns
on screen in the following order.

GENERAL ADJUSTMENTS

Signals Picture

Normal picture

All white

2) Press “8” button while any built-in test pattern to on the screen to output the 1 kHz sound. Press the button again to
cut off the sound.

Note: If the video cable is connected to the VIDEO1 INPUT jack, the built-in pattern signals are not displayed.

• All White

– 7 –

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.

SELF CHECK










GENERAL ADJUSTMENTS

 Part number of microprocessor (QA01)

 Operation number of protection circuit (current limiter) . . . . “000” is normal.

 BUS line check “OK” ................... Normal

 BUS line ACK (acknowledge) check

 Sync. signal check Green display ..... Normal

 ID code for TV set
 Version of "EEP"
 Data for "OPT"

NO. 23 * * * * * *
POWER : 000
BUS LINE : OK
BUS CONT : OK
BLOCK : MAIN SUB
SET ID : FF
EEP VER : FF
OPT1 : 02 OPT2 : A4

DVI
NO 23009621
ERR CODE : 030000

“SCL-GND” or “NG” .......... SCL-GND short circuit

“SDA-GND” or “NG” .......... SDA-GND short circuit

“SCL-SDA” or “NG” ........... SCL-SDA short circuit

“OK” ..................... Normal

Display of Location Number . . . . NG

(Display example)
“QA02 NG”, “H001 NG”, “Q501 NG” etc.
Note: The indication of failure place is only one place though failure places are plural. When

repair of a failure place finishes, the next failure place is indicated. (The order of priority of
indication is left side.)

Cyan display ...... No check

Red display ........ NG

MAIN....... Main sync

SUB ........ Sub sync (when turn on the PIP)

– 8 –

ELECTRICAL ADJUSTMENTS

ITEM ADJUSTMENT PROCEDURE

FOCUS VR ADJ

SUB-BRIGHTNESS
(BRTC)

SUB-COLOR
(SCOL)
SUB-TINT
(TNTC)

1. Enter the service mode, then select any register item.

2. Press the TV/VIDEO button on the Remote until the black cross-bar pattern ap­pears on the screen.

3. Adjust the FOCUS control (on T461) for well defined scanning lines on the picture
screen.

1. Constrict the picture height until the verti­cal retrace line appears adjusting the item
HIT (HEIGHT).

2. Adjust the CONTRAST control to the mini­mum.

3. Call up the adjustment mode display, then
select the item BRTC.

4. Press the VOLUME s or t button so the
belt of vertical retrace line just disappear.

5. Adjust the CONTRAST control for the de­sired contrast.

6. Perform the HEIGHT adjustment.

Vertical retrace line

1. Receive color-bar signal from color-bar
generator.

2. Press the RESET button.

3. Connect oscilloscope to TP501 on SIG­NAL board.

4. Adjust the CONTRAST control to the
minimum.

Magenta

0

Blue

2

3 (1.6V

5. Call up the adjustment mode display,
then select the item TNTC.

6. Adjust the SUB-TINT by pressing the
VOLUME s or t button to obtain a blue
bar to magenta bar ratio of 3:2 as shown.

7. Press the RESET button.

8. Select the item SCOL.

9. Adjust the SUB-COLOR by pressing the VOLUME s or t button to achieve

1.6V0-p of a blue bar on scope.

10. Check the picture with off-air signal.

0-P

GENERAL ADJUSTMENTS

)

WIDTH
(WID)

1. Call up the adjustment mode display, then select the item WID.

2. Press the VOLUME s or t button to get the picture so the left and right edges of
raster begins to lack.

3. Press the VOLUME s or t button to advance the data by 7 steps.

Note : Check the horizontal picture position is correct.

– 9 –

ITEM ADJUSTMENT PROCEDURE

E-W PARABOLA (DPC)
(PARA)

GENERAL ADJUSTMENTS

HORIZONTAL POSITION
(HPOS)
VERTICAL POSITION
(VPOS)

HEIGHT
(HIT)

1. Call up the adjustment mode display, then select the item PARA.

2. Press the TV/VIDEO button on Remote until the cross-hatch pattern appears on
the screen.

3. Press the VOLUME s or t button to make vertical lines straight as shown below.

1. Call up the adjustment mode display, then select the item HPOS or VPOS.

2. Press the TV/VIDEO button on Remote until the
white cross-bar or black cross-bar pattern appears
on the screen.

3. Adjust the HORIZONTAL and VERTICAL position
alternately by pressing the VOLUME s or t but­ton for proper picture position.

4. Check the picture with off-air signal.

1. Call up the adjustment mode display, then select the item HIT.

2. Press the VOLUME s or t button to get the picture so the top of raster begins to
lack.

3. Press the VOLUME s button to advance the data by 9 steps.

Note : Check the vertical picture position is correct.

WHITE BALANCE
(RCUT)
(GCUT)
(BCUT)
(GDRV)
(BDRV)

1. Adjust the CONTRAST control to the center, and BRIGHTNESS control to the
maximum.

2. Call up the adjustment mode display, and press the TV/VIDEO button on Remote
until the white and black pattern appears on the screen.

3. Adjust the following items with the CHANNEL s/t and VOLUME s/t buttons.

RCUT

Item :

GCUT

Item :

BCUT

Item :

4. Press the TV/VIDEO button on TV to display a single horizontal line on the screen.

5. Turn the SCREEN control (FBT) fully counterclockwise and gradually rotate clock­wise until the first horizontal line appears slightly on the screen.

6. Press the TV/VIDEO button to display the normal picture.

7. Adjust the remaining two “?CUT” items (CHANNEL s/t → TV/VIDEO → VOL-
UME s/t in order) to obtain the slightly lighted horizontal line in the same levels of
three (red, green, blue) colors. The line should be white if the adjustments are
proper.

Data : 40H
Data : 40H
Data : 40H

Bright area
Adjust "GDRV" or "BDRV" to be white.

Dark area
Fine adjust "RCUT", "GCUT" or "BCUT" to be black.

Item :

GDRV Data : 40H

Item :

BDRV Data : 40H

– 10 –

CIRCUIT CHECKS

HIGH VOLTAGE CHECK
CAUTION: There is no HIGH VOLTAGE ADJUSTMENT on

this chassis. Checking should be done following the steps
below.

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 must be measured below (B) kV.

Refer to table-1 for high voltage (B).
(See SETTING & ADJUSTING DATA on page 12)

4. Vary the BRIGHTNESS control to both extremes to be sure
the high voltage does not exceed the limit under any con­ditions.

FS CIRCUIT CHECK

The Fail Safe (FS) circuit check is indispensable for the final
check in servicing. Checking should be done following the
steps below.

1. Turn the receiver on and press the RESET button.

2. Temporarily short TP-(R) and TP-(X) with a jumper wire.
Raster and sound will disappear.

3. The receiver must remain in this state even after removing
the jumper wire. This is the evidence that the FS circuit is
functioning properly.

4. To obtain a picture again, temporarily turn the receiver off
and allow the FS circuit more than 5 seconds to reset. Then
turn the power switch on to produce a normal picture.

Troubleshooting Guide for Fail Safe Circuit

Check that the set returns to normal operation when pin 12
of Z801(or emitter of Q472) is grounded with jumper wire.

YES NO

Check the voltage across
Capacitor C471 is
approximately

Refer to table –3 for
FBT detection voltage

YES

Defective Fail Safe Circuit

(C)

volts.

(C)

(See SETTING & ADJUSTING
DATA on page 12)

.

NO

Faulty power
circuit or hori­zontal circuit.

GENERAL ADJUSTMENTS

– 11 –

CHAPTER 2 SPECIFIC INFORMATIONS

SAFETY INSTRUCTIONS

SERVICE MODE

GENERAL ADJUSTMENTS

ADJUSTING ITEMS AND DATA IN THE SERVICE MODE:

SETTING & ADJUSTING DATA

34"
HIGH VOLTAGE AT ZERO BEAM: (A) 30.0 kV
MAX HIGH VOLTAGE:

Table-1

(B) 35.0 kV

Item Name of adjustment

RCUT
GCUT
BCUT
GDRV
BDRV
BRTC
TNTC

SPECIFIC INFORMATIONS

SCNT
HIT

CIRCUIT CHECKS

R CUT OFF
G CUT OFF
B CUT OFF
G DRIVE
B DRIVE
BRIGHT CENTER
TINT CENTTER
SUB CONTRAST
PICTURE HIT

(Basis)

(Basis)

(Basis)

(Basis 1,4,7,10)

(Basis 1,4,7,10)

(1-12)

(1,2,3)

(1,2,3)

(1080)

Preset

40H
40H
40H
40H
40H
80H
46H
15H
38H

NORMAL

& FULL

←

←

←

←

←

←

←

12H
24H

Table-2

FBT DETECTION VOLTAGE (C) 20.1 V

Table-3

Item Name of adjustment Preset

LIN
WID
PARA
CNR
TRAP
HPS
TCNR
BCNR
VPSI

V-LINEARITY
PICTURE WIDTH
E-W PARABOLA
EW M CORRECTION
EW TRAPEZIUM
H-POSITION
EW TOP CORNER
EW BOTTOM COR
VTRAP (VPS1)

(1080)

(1080)

(1080)

(1080)
(1080)

(1080)

12H
00H
16H
15H
35H
39H
14H
10H
82H

NORMAL

& FULL

←

20H

←

←

←

46H

←

←

6DH

– 12 –