Toshiba 20AS25 Schematic

FILE NO. 050-200501

DOCUMENT CREATED IN JAPAN, Jan., 2005

SERVICE MANUAL

COLOR TELEVISION

20AS25

SERVICING NOTICES ON CHECKING

As for the places which need special attentions, they are indicated with the labels or seals on the cabinet, chassis and parts. Make sure to keep the indications and notices in the operation manual.

2. AVOID AN ELECTRIC SHOCK

There is a high voltage part inside. Avoid an electric shock while the electric current is flowing.

3. USE THE DESIGNATED PARTS

The parts in this equipment have the specific characters of incombustibility and withstand voltage for safety. Therefore, the part which is replaced should be used the part which has the same character. Especially as to the important parts for safety which is indicated in the circuit diagram or the table of parts as a mark, the designated parts must be used.

4. PUT PARTS AND WIRES IN THE ORIGINAL POSITION AFTER ASSEMBLING OR WIRING

There are parts which use the insulation material such as a tube or tape for safety, or which are assembled in the condition that these do not contact with the printed board. The inside wiring is designed not to get closer to the pyrogenic parts and high voltage parts. Therefore, put these parts in the original positions.

5. TAKE CARE TO DEAL WITH THE CATHODE-RAY TUBE

In the condition that an explosion-proof cathoderay tube is set in this equipment, safety is secured against implosion. However, when removing it or serving from backward, it is dangerous to give a shock. Take enough care to deal with it.

6. AVOID AN X-RAY1. KEEP THE NOTICES

Safety is secured against an X-ray by considering about the cathode-ray tube and the high voltage peripheral circuit, etc. Therefore, when repairing the high voltage peripheral circuit, use the designated parts and make sure not modify the circuit. Repairing except indicates causes rising of high voltage, and it emits an X-ray from the cathoderay tube.

PERFORM A SAFETY CHECK AFTER

7. SERVICING

Confirm that the screws, parts and wiring which were removed in order to service are put in the original positions, or whether there are the portions which are deteriorated around the serviced places serviced or not. Check the insulation between the antenna terminal or external metal and the AC cord plug blades. And be sure the safety of that.

(INSULATION CHECK PROCEDURE)

Unplug the plug from the AC outlet.

1. Remove the antenna terminal on TV and turn

2. on the TV. Insulation resistance between the cord plug

3. terminals and the eternal exposure metal [Note 2] should be more than 1M ohm by using the 500V insulation resistance meter [Note 1]. If the insulation resistance is less than 1M

4. ohm, the inspection repair should be required.

[Note 1]

If you have not the 500V insulation resistance meter, use a Tester.

[Note 2]

External exposure metal: Antenna terminal

Earphone jack

HOW TO ORDER PARTS

Please include the following informations when you order parts. (Particularly the VERSION LETTER.)

1. MODEL NUMBER and VERSION LETTER The MODEL NUMBER can be found on the back of each product and the VERSION LETTER can be

found at the end of the SERIAL NUMBER.

2. PART NO. and DESCRIPTION You can find it in your SERVICE MANUAL.

IMPORTANT

Inferior silicon grease can damage IC's and transistors. When replacing an IC's or transistors, use only specified silicon grease (YG6260M). Remove all old silicon before applying new silicon.

A1-1

ABOUT LEAD FREE SOLDER (PbF)

Distinction of PbF PCB:

PCBs (manufactured) using lead free solder will have a PbF printing on the PCB. (Please refer to figures.)

Caution:

Pb free solder has a higher melting point than standard solder;

•

Typically the melting point is 50°F~70°F(30°C~40°C) higher. Please use a soldering iron with temperature control and adjust it to 650°F ± 20°F (350°C ± 10°C). In case of using high temperature soldering iron, please be carefull not to heat too long. Pb free solder will tend to splash when heated too high (about 1100°F/ 600°C).

•

All products with the printed circuit board with PbF printing must be serviced with lead free solder.

•

When soldering or unsoldering, completely remove all of the solder from the pins or solder area, and be sure to heat the soldering points with the lead free solder until it melts sufficiently.

Recommendations

Recommended lead free solder composition is Sn-3.0Ag-0.5Cu.

A1-2

CONTENTS

SERVICING NOTICES ON CHECKING......................................................................................................

HOW TO ORDER PARTS ...........................................................................................................................

IMPORTANT................................................................................................................................................

ABOUT LEAD FREE SOLDER (PbF).........................................................................................................

CONTENTS .................................................................................................................................................

GENERAL SPECIFICATIONS ....................................................................................................................

DISASSEMBLY INSTRUCTIONS

1.REMOVAL OF ANODE CAP ..............................................................................................................

2.REMOVAL AND INSTALLATION OF FLAT PACKAGE IC ...............................................................

SERVICE MODE LIST.................................................................................................................................

CONFIRMATION OF HOURS USED ..........................................................................................................

WHEN REPLACING EEPROM (MEMORY) IC ...........................................................................................

ELECTRICAL ADJUSTMENTS ..................................................................................................................

BLOCK DIAGRAM ......................................................................................................................................

PRINTED CIRCUIT BOARDS

MAIN/CRT...............................................................................................................................................

SCHEMATIC DIAGRAMS

MICON/CHROMA/TUNER......................................................................................................................

TV POWER.............................................................................................................................................

DEFLECTION/CRT.................................................................................................................................

SOUND/AV .............................................................................................................................................

WAVEFORMS .............................................................................................................................................

MECHANICAL EXPLODED VIEW ..............................................................................................................

MECHANICAL REPLACEMENT PARTS LIST ..........................................................................................

ELECTRICAL REPLACEMENT PARTS LIST ............................................................................................

A1-1 A1-1 A1-1 A1-2 A2-1 A3-1~A3-5

B1-1 B2-1, B2-2 C-1 C-1 C-1 D-1~D-4 E-1, E-2

F-1~F-4 G-1, G-2

G-3, G-4 G-5, G-6 G-7, G-8 H-1, H-2 I-1, I-2 J1-1 J2-1~ J2-3

A2-1

GENERAL SPECIFICATIONS

G-1 TV CRT CRT Size / Visual Size 19 inch / 480.0mmV

System CRT Type Normal

Deflection

Magnetic Field BV/BH +0.35G/0.30G Color System NTSC Speaker 1Speaker

Position Bottom

Size

Impedance 8 ohm Sound Output MAX

10%(Typical) NTSC3.58+4.43 /PAL60Hz No

G-2 Tuning Broadcasting System US System M

System Tuner and System 1Tuner

Receive CH Destination USA(W/ CATV)

Tuning System F-Synth

Input Impedance VHF/UHF 75 ohm

CH Coverage A - I, J - W, W+1 - W+84 Intermediate Picture(FP) 45.75MHz Frequency Sound(FS) 41.25MHz

FP-FS 4.50MHz Preset CH No Stereo/Dual TV Sound No Tuner Sound Muting Yes

G-3 Power Power Source AC 120V AC 60Hz

DC Power Consumption at AC

Stand by (at AC)

Per Year Protector Power Fuse Yes

G-4 Regulation Safety UL

Radiation FCC

X-Radiation DHHS

G-5 Temperature Operation +5oC ~ +40oC

Storage -20oC ~ +60oC

G-6 Operating Humidity Less than 80% RH

90 degree

3 Inch

1.5 W

1.0 W

2 - 69, 4A, A-5 - A-1,

73 W at AC 120 V 60 Hz 5 W at AC 120 V 60 Hz

-- kWh/Year

A3-1

GENERAL SPECIFICATIONS

G-7 On Screen Menu Yes

Display Menu Type Character

G-8 OSD Language English French Spanish

Picture Yes

Contrast Yes

Brightness Yes

Color Yes

Tint Yes

Sharpness Yes

Audio No

Bass No

Treble No

Balance No

BBE On/Off No

Stable Sound On/Off No

CH Set Up Yes

TV/CABLE(CATV) Yes

Auto CH Memory Yes

Add/ Delete Yes

Language Yes V-chip Yes Lock Yes On Timer Yes

CH Label No

Favorite CH No

Color Stream DVD/DTV No

Control Level Yes

Volume Yes

Brightness Yes

Contrast Yes

Color Yes

Tint Yes

Sharpness Yes

Tuning No

Bass No

Treble No

Balance No

Back Light No

Stereo,Audio Output,SAP No Video Yes Color Stream No Channel(TV/Cable) Yes CH Label No Game Timer Yes Sleep Timer Yes Sound Mute Yes V-chip Rating Yes

G-9 Clock and Sleep Timer Max Time 120 Min

Timer Step

On Timer Program(On Timer ) Yes Wake Up Timer No Timer Back-up (at Power Off Mode) more than -- Min Sec

10 Min

A3-2

GENERAL SPECIFICATIONS

G-10 Remote Unit RC-EH

Control Glow in Dark Remocon Yes[From '04 DEC O/R]

Format Toshiba Custom Code Power Source Voltage(D.C) 3V

UM size x pcs UM-4 x 2 pcs Total Keys Keys Power Yes

1 Yes

2 Yes

3 Yes

4 Yes

5 Yes

6 Yes

7 Yes

8 Yes

9 Yes

0 Yes

100 No

CH Up Yes

CH Down Yes

Volume Up Yes

Volume Down Yes

TV/Caption/Text Yes

CH1/CH2 Yes

TV/Video(TV/AV) Yes

CH RTN/CH ENT(Quick View) Yes

Sleep Yes

RE Call(Call) Yes

Reset Yes

Menu Yes

Enter Yes

Mute Yes

Exit No

MTS(Audio Select) No

Set + Yes

Set - Yes Multi Brand Keys CH Up(VCR) No

CH Down(VCR) No

Pause/Still No

TV/VCR(VCR) No

Code No

FF No

Rew No

Rec No

Play No

Stop No

TV No

VCR No

Cable No

40-BF h

27 Keys

A3-3

GENERAL SPECIFICATIONS

G-11 Features Auto Degauss Yes

G-12 Accessories Owner's Manual Language English / Spanish

Auto Shut Off Yes Canal+ No CATV Yes Anti-theft No Rental No Memory(Last CH) Yes Memory(Last Volume) Yes V-Chip Yes

Type BBE No Auto Search No CH Allocation No SAP No Just Clock Function No CH Label No VM Circuit No Full OSD No Premiere No Comb Filter No

Auto CH Memory Yes Hotel Lock No Closed Caption Yes Stable Sound No FBT Leak Test Protect Yes CH Lock Yes Video Lock Yes Game Timer (Max Time:120 Min) Yes Stable Sound No Energy Star No Power On Memory Yes Favorite CH No

W/ Warranty Remote Control Unit Yes Rod Antenna No

Poles

Terminal Loop Antenna

Terminal U/V Mixer DC Car Cord (Center+) Guarantee Card Yes Warning Sheet Circuit Diagram Antenna Change Plug Service Facility List Important Safety Instruction Dew/AHC Caution Sheet AC Plug Adapter Quick Set-up Sheet Battery Yes

UM size x pcs UM4 x 2

OEM Brand AC Cord AV Cord (2Pin-1Pin) Registration Card (NDL Card) ESP Card PTB Sheet 300 ohm to 75 ohm Antenna Adapter

USA,ORION Type

Lines

No No

No No No No No No No No

No No No No No No No

A3-4

GENERAL SPECIFICATIONS

G-13 Interface Switch Front Power Yes

Rear AC/DC No

Indicator Power Yes

Terminals Front Video Input

Rear Video Input(Rear1)

G-14 Set Size Approx. W x D x H (mm) G-15 Weight Net (Approx.)

G-16 Carton Master Carton

Gift Box Yes

Drop Test

Container Stuffing

G-17 Cabinet Material Cabinet Cabinet Front PS 94V0 DECABROM

PCB Non-Halogen Demand

G-18 Environment Pb Free Phase3

System Select No

Main Power SW No

Sub Power No

Channel Up/Reset Yes

Channel Down/Enter Yes

Volume Up/Set Up Yes

Volume Down/Set Down Yes

MENU=Volume Up+Volume Down Yes

TV/CATV Selector No

Degauss No

Main Power SW No

Stand-by No

On Timer No

Audio Input

Other Terminal

Video Input(Rear2)

Audio Input(Rear1)

Audio Input(Rear2)

Video Output

Audio Output

Euro Scart

Color Stream

Diversity No

Ext Speaker No

DC Jack 12V(Center +) No

VHF/UHF Antenna Input

AC Outlet No

Gross (Approx.)

Content

Material

Dimensions W x D x H(mm)

Description of Origin

Material Double/Brown

Dimensions W x D x H(mm)

Design As per Buyer's

Description of Origin Yes

Height (cm) 60 (ORION SPEC:46)

Cabinet Rear PS 94V0 DECABROM

Eyelet Demand Yes

RCA RCA x 1

F Type 488 x 465 x 416

17.5kg

20.0kg

----

-- x -- x --

546 x 526 x 472

Natural Dropping At 1 Corner / 2 Edges / 4

436

No No No No No No No No No

( 38.6 lbs) ( 44.1lbs) No Sets /--

Surfaces

Sets/40' container

A3-5

DISASSEMBLY INSTRUCTIONS

1. REMOVAL OF ANODE CAP

Read the following NOTED items before starting work. *

After turning the power off there might still be a potential voltage that is very dangerous. When removing the Anode Cap, make sure to discharge the Anode Cap's potential voltage.

Do not use pliers to loosen or tighten the Anode Cap terminal, this may cause the spring to be damaged.

REMOVAL

1. Follow the steps as follows to discharge the Anode Cap.

(Refer to Fig. 1-1.)

Connect one end of an Alligator Clip to the metal part of a flat-blade screwdriver and the other end to ground. While holding the plastic part of the insulated Screwdriver, touch the support of the Anode with the tip of the Screwdriver. A cracking noise will be heard as the voltage is discharged.

GND on the CRT

3. After one side is removed, pull in the opposite direction to remove the other.

NOTE

Take care not to damage the Rubber Cap.

INSTALLATION

1. Clean the spot where the cap was located with a small amount of alcohol. (Refer to Fig. 1-3.)

Location of Anode Cap

Fig. 1-3

NOTE

Confirm that there is no dirt, dust, etc. at the spot where the cap was located.

2.3.Arrange the wire of the Anode Cap and make sure the wire is not twisted. Turn over the Rubber Cap. (Refer to Fig. 1-4.)

Screwdriver

Alligator Clip

GND on the CRT

Flip up the sides of the Rubber Cap in the direction of the

2. arrow and remove one side of the support.

(Refer to Fig. 1-2.)

Rubber Cap

CRT

Support

CRT

Fig. 1-1

Fig. 1-2

4. Insert one end of the Anode Support into the anode button, then the other as shown in Fig. 1-5.

Support

CRT

5.6.Confirm that the Support is securely connected. Put on the Rubber Cap without moving any parts.

B1-1

Fig. 1-4

Fig. 1-5

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