TOSHIBA 34HF83 - Service Manual Immediate Download

FILE NO. 070-200307

SERVICE MANUAL

COLOR TELEVISION

N3WS Chassis

34HF83

PUBLISHED IN JAPAN.

May. 2003

(TAC0322)

GENERAL

ADJUSTMENTS

TABLE OF CONTENTS

CHAPTER 1 GENERAL ADJUSTMENTS

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

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

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

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

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

CHAPTER 2 SPECIFIC INFORMATIONS

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

APPENDIX:

CIRCUIT DIAGRAM

GENERAL

ADJUSTMENTS

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 hazardous

X-RAY RADIATION. To avoid such hazards, the high volt-

age 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 cir-

cumstances, 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 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. 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, follow-

ing 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 pro-

tection, 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 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

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 combi-

nation of 1500 ohm resistor and 0.15

µF capacitor. Re-

verse 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 consti-

tutes a potential shock hazard and must be corrected im-

mediately.

WARNING : Service should not be attempted by anyone unfa-

miliar with the necessary precautions on this receiver. The fol-

lowing 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 serv-

ice is performed on the receiver.

2. Always discharge the picture tube anode to the CRT con-

ductive coating before handling the picture tube. The pic-

ture tube is highly evacuated and if broken, glass frag-

ments will be violently expelled. Use shatter proof gog-

gles and keep picture tube away from the unprotected body

while handling.

3. When replacing a chassis in the cabinet, always be cer-

tain 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:

AC VOLTMETER

0.15

µF

Good earth ground

such as a water

pipe, conduit, etc.

Place this probe on

each exposed

metallic part.

1500 ohm

10 watt

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 charac-

teristics 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.

GENERAL

ADJUSTMENTS

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

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

SET-UP ADJUSTMENT FOR FLAT TUBE

I 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

(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.

Figure 1.

(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

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

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

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

I 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.

P/C magnet installing position A

· 30"=26.5 mm

· 32"=30.5 mm or 32.5 mm

· 34"=37 mm

· 34"=39 mm

Green Belt

2-pole purity magnet

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

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

6-pole convergence magnet (34")

Sub-4-pole convergence magnet (32" : 34")

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

6-pole convergence magnet (30" : 32")

Main 4-pole convergence magnet (34")

Fix the deflection yoke at a position 60% forward from a point

between (6) and (7)

Picture tube

Shift deflection yoke

(6)

(8)

(7) Perform marking of each point on

the tape of picture tube

CRT-D board

P/C Mag

100 60 0%

GENERAL

ADJUSTMENTS

(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

red

Main 4-pole magnet

red/blue

green

6-pole magnet

Xv bow-shaped deviation of convergence

blue

red

Sub-4-pole magnet

I CIRCUMFERENCE CONVERGENCE:

* Perform correction in the following manner.

VR3

YV YHC

VR2 VR1

blue

green

red

· Adjust coils and minimize deviation

(The 27" unit has coils underneath it)

blue

green

red

(Parts code:23 948 274) TC-S

Blue color or blue mark

*Insert the correction piece between the

picture tube and the deflection yoke.

(Insertion position of correction

piece)

Bonded surface

blue

green

red

(Parts code:23 948 464)

Transparent

Bonded surface

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

Red

green

blue

Red

green

blue

Red

green

blue

Red

green

blue

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

Red

green

blue

Red

green

blue

Red

green

blue

Red

green

blue

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

Red

blue

green

Red

blue

green

Red

blue

green

Red

blue

green

Red

blue

green

blue

red

green

Red

blue

green

blue

red

green

I 30", 27", 32"

I 34"

27" (Part No. 23 947 371)

32", 30" (Part No. 23 947 121)

34" (Part No. 23 993 080)

Perform correction by inserting the

correction piece into the clear-

ance 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.