HP A4576 Service Manual

A4576

SERVICE MANUAL

SPECIFICATIONS

N.Hemisphere Model

Canadian Model

US Model

chassis No. SCC-L04L-A

AEP Model

Chassis No. SCC-L04G-A

N3

CHASSIS

COLOR GRAPHIC DISPLAY

HP

A4576

SAFETY CHECK-OUT

(US Model only)

After correcting the original service problem, perform the fol­lowing safety checks before releasing the set to the customer:

1. Check the area of your repair for unsoldered or poorly-sol­dered connections. Check the entire board surface for solder
splashes and bridges.

2. Check the interboard wiring to ensure that no wires are
“pinched” or contact high-wattage resistors.

3. Check that all control knobs, shields, covers, ground straps,
and mounting hardware have been replaced. Be absolutely
certain that you have replaced all the insulators.

4. Look for unauthorized replacement parts, particularly transis­tors, that were installed during a previous repair. Point them
out to the customer and recommend their replacement.

5. Look for parts which, though functioning, show obvious signs
of deterioration. Point them out to the customer and recom­mend their replacement.

6. Check the line cords for cracks and abrasion. Recommend the
replacement of any such line cord to the customer.

7. Check the B+ and HV to see if they are specified values. Make
sure your instruments are accurate; be suspicious of your HV
meter if sets always have low HV.

8. Check the antenna terminals, metal trim, “metallized” knobs,
screws, and all other exposed metal parts for AC Leakage.
Check leakage as described below.

To Exposed Metal
Parts on Set

AC

0.15 µF

1.5 k

Ω

Earth Ground

Voltmeter
(0.75 V)

Fig. A. Using an AC voltmeter to check AC leakage.

CAUTION ON DAS (ECS) CONNECTOR

• The connector for DAS (ECS) adjustment is provided inside the

cover shown below. Be careful with an electrical shock when
connecting the connector with the power supplied. Also, return
the removed cover to the home position.

Rear side

LEAKAGE TEST

The AC leakage from any exposed metal part to earth ground
and from all exposed metal parts to any exposed metal part
having a return to chassis, must not exceed 0.5 mA (500
microampers).
Leakage current can be measured by any one of three meth­ods.

1. A commercial leakage tester, such as the Simpson 229 or
RCA WT-540A. Follow the manufacturers’ instructions to
use these instruments.

2. A battery-operated AC milliammeter. The Data Precision 245
digital multimeter is suitable for this job.

3. Measuring the voltage drop across a resistor by means of a
VOM or battery-operated AC voltmeter. The “limit” indica­tion is 0.75 V, so analog meters must have an accurate low­voltage scale. The Simpson 250 and Sanwa SH-63Trd are ex­amples of a passive VOMs that are suitable. Nearly all battery
operated digital multimeters that have a 2 V AC range are suit­able. (See Fig. A)

WARNING!!
NEVER TURN ON THE POWER IN A CONDITION IN
WHICH THE DEGAUSS COIL HAS BEEN REMOVED.

SAFETY-RELATED COMPONENT WARNING!!

COMPONENTS IDENTIFIED BY SHADING AND MARK

¡ ON THE SCHEMATIC DIAGRAMS, EXPLODED

VIEWS AND IN THE PARTS LIST ARE CRITICAL FOR
SAFE OPERATION. REPLACE THESE COMPONENTS
WITH SONY PARTS WHOSE PART NUMBERS AP­PEAR AS SHOWN IN THIS MANUAL OR IN SUPPLE­MENTS PUBLISHED BY SONY. CIRCUIT ADJUST­MENTS THAT ARE CRITICAL FOR SAFE OPERATION
ARE IDENTIFIED IN THIS MANUAL. FOLLOW THESE
PROCEDURES WHENEVER CRITICAL COMPO­NENTS ARE REPLACED OR IMPROPER OPERATION
IS SUSPECTED.

AVERTISSEMENT!!
NE JAMAIS METTRE SOUS TENSION QUAND LA
BOBINE DE DEMAGNETISATION EST ENLEVÉE.

ATTENTION AUX COMPOSANTS RELATIFS À LA

SÉCURITÉ!!
LES COMPOSANTS IDENTIFIÉS PAR UNE TRAME ET
UNE MARQUE
SÉCURITÉ. NE LES REMPLACER QUE PAR UNE PIÈCE
PORTANT LE NUMÉRO SPECIFIÉ. LES RÉGLAGES DE
CIRCUIT DONT L’IMPORTANCE EST CRITIQUE POUR
LA SÉCURITÉ DU FONCTIONNEMENT SONT
IDENTIFIÉS DANS LE PRÉSENT MANUEL. SUIVRE CES
PROCÉDURES LORS DE CHAQUE REMPLACEMENT
DE COMPOSANTS CRITIQUES, OU LORSQU’UN
MAUVAIS FONCTIONNE-MENT EST SUSPECTÉ.

– 2 –

¡ SONT CRITIQUES POUR LA

POWER SAVING FUNCTION

DIAGNOSIS

A4576

+B failure

Failure

Yellow → Off

Power LED

(0.5 sec) (0.5 sec)

Horizontal / Vertical Deflection failure,
Thermal protector

ABL protector

Yellow → Off

(1.5 sec) (0.5 sec)

Yellow → Off

(0.5 sec) (1.5 sec)

HV failure

Yellow → Off → Yellow → Off

(0.25 sec) (0.5 sec) (0.25 sec) (1.25 sec)

Aging / Self Test

Yellow → Off → Green → Off

(0.5 sec) (0.5 sec) (0.5 sec) (0.5 sec)

Aging Mode (Video Aging) : During Power Save, press “MENU” key for longer than 2 second.
Self Test (OSD Color Bar) : During Power Save, press “CONTRAST” + (/) key for longer than 2 second.
Reliability Check Mode : During Power Save, press “CONTRAST” – (?) key for longer than 2 second.

TIMING SPECIFICATION

MODE AT PRODUCTION MODE 1 MODE 2 MODE 3 MODE 4 MODE 5 MODE 6 MODE 7 MODE 8 MODE 9 MODE 10
RESOLUTION
CLOCK
—HORIZONTAL—
H-FREQ

H. TOTAL 31.778 23.111 18.631 16.660 14.561 12.800 12.504 10.971 10.667 9.412
H. BLK 6.356 5.333 4.409 3.657 3.725 3.319 3.022 2.844 2.765 2.44
H. FP 0.636 1.556 0.569 0.203 0.508 0.474 0.119 0.406 0.316 0.279
H. SYNC 3.813 1.556 1.138 1.219 1.016 1.422 1.067 1.016 0.948 0.837
H. BP 1.907 2.222 2.702 2.235 2.201 1.422 1.837 1.422 1.501 1.325
H. ACTIV 25.422 17.778 14.222 13.003 10.836 9.481 9.481 8.127 7.901 6.972
— VERTICAL —
V. FREQ(HZ) 69.931 Hz 85.008 Hz 85.061 Hz 75.029 Hz 84.997 Hz 72.005 Hz 75.025 Hz 85.024 Hz 75.000 Hz 85.000 Hz

V. TOTAL 450 509 631 800 808 1085 1066 1072 1250 1250
V. BLK 50 29 31 32 40 61 42 48 50 50
V. FP 12111131 111
V. SYNC 2 3 3 3 3 3 3 3 3 3
V. BP 36 25 27 28 36 55 38 44 46 46
V. ACTIV 400 480 600 768 768 1024 1024 1024 1200 1200
— SYNC —
INT(G) NO NO NO NO NO YES NO NO NO NO
EXT(H/V)/POLARITY YES N/P YES N/N YES P/P YES P/P YES P/P NO YES P/P YESP/P YES P/P YES P/P
EXT(CS)/POLARITY NO NO NO NO NO NO NO NO NO NO
INT/NON INT NON INT NON INT NON INT NON INT NON INT NON INT NON INT NON INT NON INT NON INT

640 X 400 640 X 480 800 X 600 1024 X 768 1024 X 768 1280 X 1024 1280 X 1024 1280 X 1024 1600 X 1200 1600 X 1200

25.175 MHz 36.000 MHz 56.250 MHz 78.750 MHz 94.500 MHz 135.000 MHz 135.000 MHz 157.500 MHz 202.500 MHz 229.500 MHz

31.469 kHz 43.269 kHz 53.674 kHz 60.023 kHz 68.677 kHz 78.125 kHz 79.976 kHz 91.146 kHz 93.750 kHz 106.250 kHz
usec usec usec usec usec usec usec usec usec usec

lines lines lines lines lines lines lines lines lines lines

97.9.19 VER.

– 3 –

A4576

TABLE OF CONTENTS

Section Title Page

1. GENERAL................................................................... 1-1

2. DISASSEMBLY

2-1. Cabinet Removal .................................................. 2-1

2-2. D Board Removal ................................................ 2-1

2-3. G Board Removal ................................................ 2-2

2-4. A Board Removal ................................................ 2-2

2-5. L Board Removal ................................................. 2-3

2-6. I/O Terminal Board Removal ............................... 2-3

2-7. Service Position .................................................... 2-4

2-8. H and J Boards Removal ..................................... 2-4

2-9. Picture Tube Removal ......................................... 2-5

3. SAFETY RELATED ADJUSTMENT............. 3-1

4. ADJUSTMENTS ...................................................... 4-1

5. DIAGRAMS

5-1. Block Diagrams .................................................... 5-1

5-2. Frame Shcematic Diagram.................................... 5-7

5-3. Circuit Boards Location........................................ 5-9

5-4. Schematic Diagrams and Printed Wiring Boards..... 5-9

(1) Schematic Diagram of D Board ........................ 5-13

(2) Schematic Diagrams of G, GA, H,

J and L Boards .................................................. 5-17

(3) Schematic Diagram of A Board ........................ 5-24

5-5. Semiconductors ................................................. 5-29

6. EXPLODED VIEWS

6-1. Chassis ................................................................. 6-1

6-2. Picture Tube ......................................................... 6-2

6-3. Packing Materials ................................................ 6-3

7. ELECTRICAL PARTS LIST ............................ 7-1

Note: Hand degauss must be used on stand-by or power-off condition.

This model has an automatic earth magnetism correction function by using an earth
magnetism sensor and a LCC coil. When using a hand degauss while monitor (LCC
coil) is being operated, it sometimes gets magnetized, and the system may not work
properly as a result.

– 4 –

1-1

SECTION 1

GENERAL

The operating instructions mentioned here are partial abstracts
from the Operating Instruction Manual. The page numbers of
the Operating Instruction Manual remain as in the manual.

1-2

1-3

1-4

1-5

1-6

1-7

1-8

2-1. CABINET REMOVAL

5

Four screws
(+ BVTT 4 x 8)

6

Top cover

SECTION 2

DISASSEMBLY

1

Screw cover

Two claws

7

Four screws
(+ BVTT 4 x 8)

3

Four screws
(+ BVTP 4 x 16)

2

Screw cover

4

Cabinet

A4576

2-2. D BOARD REMOVAL

4 5

Screw
(+ P 3.5 x 20)

6

D board

Two screws
(+ BVTP 3 x 10)

8

Video shield

1

Screw
(+ BVTT 4 x 8)

2

Two screws
(+ BVTT 4 x 8)

B

Three hooks

3

Open the D block in the direction
of the arrow . and remove of
the arrow .

2-1

A

A

B

A4576

2-3. G BOARD REMOVAL

1

Screw
(+ BVTT 4 x 8)

2

Two screws
(+ BVTT 4 x 8)

B

A

4

Two screws
(+BVTP 3 x 10)

5

G shield

7

G board

3

Open the G block in the direction
of the arrow . and remove of
the arrow .

2-4. A BOARD REMOVAL

Three hooks

6

A

B

Two printed circuit board holders

2-2

A borad Three screws

12

(+BVTT 4 x 8)

2-5. L BOARD REMOVAL

CN5002

CN5001
CN5004
CN5003

2

A4576

L board

1

2-6. I/O TERMINAL BOARD REMOVAL

1

Three screws
(+ BVTT 3 x 8)

Four printed circuit board holders

CN511

CN401
CN402

2

I/O terminal board assy

2-3

A4576

2-7. SERVICE POSITION

CAUTION : SHORT

If the claw is hooked,

*

opening and closing
the board is impossible.
Do not try to do it by force.

D,G boards

G board
(Refer to 2-3.)

Rear shield

If the claw is hooked,

*

opening and closing
the board is impossible.
Do not try to do it by force.

D board (Refer to 2-2.)

A board (Refer to 2-4.)

2-8. H AND J BOARDS REMOVAL

CN891

5

Shaft

CN801

Claw

Claw

4

H board

1

Four screws
(Tapping screw 5)

6

Claw

7

J board

3

Two screws
(+ BVWHTP 3 x 12)

2

Bezel

2-4