Nad T 531 C Service Manual 2

Page 2

SECTION 1 . .
SECTION 2 . . .
SECTION 3 . . .
SECTION 4 . .
SECTION 5 . . .

CONTENTS

. .SUMMARY

.CABINET & MAIN CHASSIS
.ELECTRICAL

. .MECHANISM

.REPLACEMENT PARTS LIST

Page 9

CIRCUIT BOARD DISASSEMBLY

Note: Before removing the main circuit board, be sure to shortcircuit the laserdiode output land.
After replacing the main circuit board, open the land after inserting the flexible connector.
(Refer to Mechanism Disassembly)

1. Disassembling of Main Circuit Board

and Interface Board 2. Digitron and Key Circuit Board
1- Remove the t0P case.(See Fig. 2'1) 1. Remove the front panel.(See Fig. 2-3)
2. Remove 12 SCFeW (C)- 2. Release 4 screws (E), and remove the digitron
3. Remove the deck from Main Circuit Board. circuit board.

4. Remove Main Circuit Board from Interface Board.
5. Remove 2 screw (D).
6. Remove interface Board from the chassis.

Power Code

Fig. 2-5

Page 12

SECTION 3

ELECTRICAL
CONTENTS
ELECTRICAL TROUBLESHOOTING GUIDE ...................................................................... 3-2
1. Power(SMPS) Circuit ............................................................................................................... 3-2
2. u-com Circuit ............................................................................................................................ 3-3
3. MPEG Circuit ............................................................................................................................ 3-6
4. Front Circuit(Digitron & Key) ................................................................................................. 3-7
5. RF/Servo Circuit ..................... ..3-8
BLOCK DIAGRAMS ........ ....3-12
1. Overall Block Diagram ........... ....3-12
2. Power (SMPS) Block Diagram ....................... ....3-14
3. RF/CD DSP/DVD DSP/DVD servo Block Diagram. ....3-18
4. Audio Block Diagram ............................................ ....3-19
5. MPEG Block Diagram.. ....3-17
6. u-COM Block Diagram. ....3-18

CIRCUIT DIAGRAMS .................... ....3-19
1. Power (SMPS) Circuit Diagram ............................................................................................ 3-19
2. DVD DSP Circuit Diagram ..................................................................................................... 3-23
3. Drive & RF Circuit Diagram .................................................................................................. 3-25
4. MPEG Circuit Diagram .......................................................................................................... 3-27
5. Audio DM Circuit Diagram .................................................................................................... 3-29
6. u-COM/Expander .................................................................................................................... 3-31
7. DIGITRON & Key Circuit Diagram ........................................................................................ 3-33
8. Scart Circuit Diagram ............................................................................................................ 3-35
9. Jack Circuit Diagram ............................................................................................................. 3-37
- CIRCUIT VOLTAGE CHART .................................................................................................... 3-39
- WAVEFORMS ........................................................................................................................... 3-45
PRINTED CIRCUIT DIAGRAMS ............................................................................................ 3-47
1. MAIN P.C.BOARD ................................................................................................................... 3-47
2. POWER, A/V, FRONT P.C.BOARD ........................................................................................ 3-49
3. KEY P.C.BOARD ..................................................................................................................... 3-51
4. POWER LED P.C.BOARD ...................................................................................................... 3-51

3-1

Page 21

C.

OPEN/CLOSE

FOCUS ON?

YES

Does the disc tum?

A

YES

|0201 Pin169 is "High"?

A

YES

Is OK the track jump.

A

YES

Does the screen appear?

A

YES

E

2

D

NO

NO

NO

Check
the tocus error moving the
lens up and down.
ICZAl Pin 42

Does the
TrL level change at lCZOt
Pin 78 and 132 moving
the lens

Replace p-COM or ICZO1.

Check IC2M1 Pin 18, PMDO3
Pin 6 turn when the |02M1
Pin 21 is less than 2.2V.

Check A

Fig.3. FOCUS ERROR waveform

Check ICZAt Pin 11,12,13,14
in DVD Mode

|0201 no output : Pick-up is defective.

Replace |0201 .

Check |CZO1 and |02M1 when PMD03 Pin 6 is abnormal

Does the si na
ulse appear at | 2A1 Pins
3 2 ?

ICZA1 is defective.

Video Part is defective.
Check "5.MPEG Circuit."
Check "7.0SD/Videc Circuit."

Replace p-COM part.

3-10