HTC-NX300, MHC-NX300AV - Sony Audio Service Manual (repair manual)

E Model

Chinese Model

Dolby noise reduction manufactured under license
from Dolby Laboratories Licensing Corporation.
“DOLBY” and the double-D symbol 

;

 are trade-

marks of Dolby Laboratories Licensing Corporation.

HTC-NX300 is the CD player and Tape
Deck section in MHC-NX300AV.

CD

Section

Tape Deck
Section

Model Name Using Similar Mechanism

NEW

CD Mechanism Type

CDM53E-K3BD37

Base Unit Name Type

BU-K3BD37

Optical Pick-up Name

KSM-213BFNV/Z-NP

Model Name Using Similar Mechanism

HCD-GRX7

Tape Transport Mechanism Type

TCM-230AWR2

System

Compact disc and digital
audio system

Laser

Semiconductor laser
(

λ

=780nm)

Emission duration:
continuous

Laser output

Max. 44.6 

µ

W*

*This output is the value
measured at a distance of
200 mm from the
objective lens surface on
the Optical Pick-up Block
with 7 mm aperture.

Wavelength

780 – 790 nm

Frequency response

20 Hz – 20 kHz (

±

0.5 dB)

Signal-to-noise ratio

More than 90 dB

Dynamic range

More than 90 dB

Video color system format

NTSC, PAL

CD DIGITAL OUT
(Square optical connector jack, rear panel)
Wavelength

660 nm

Output Level

–18 dBm

Recording system

4-track 

Dimensions (w/h/d) 

Applox. 225 x 202 x 347
mm

Mass 

Applox. 4.6 kg

2-channel stereo

Frequency response

40 – 13,000 Hz (

±

3 dB),

(DOLBY NR OFF)

using Sony TYPE I
cassette
40 – 14,000 Hz (

±

3 dB),

using Sony TYPE II
cassette

Design and specifications are subject to change
without notice.

2001I0500-1

C

 2001.9

2

0

0

...............................................

3

Location of Controls .......................................................

6

.........................................................

7

.............................................................. 14

....................... 15

TAPE DECK Section ...................................................... 15
CD Section ...................................................................... 18
VIDEO Section ............................................................... 19

7-1. Block Diagram  – SERVO Section – .............................. 21
7-2. Block Diagram  – AUDIO/VIDEO CD Section – .......... 22
7-3. Block Diagram  – TAPE DECK Section – ..................... 23
7-4. Block Diagram  – POWER SUPPLY Section – ............. 24
7-5. Note for Printed Wiring Boards and

Schematic Diagrams ....................................................... 25

7-6. Printed Wiring Board  – BD Board – ............................. 26
7-7. Schematic Diagram  – BD Board – ................................ 27
7-8. Schematic Diagram  – VIDEO Board (1/2) – ................ 28
7-9. Schematic Diagram  – VIDEO Board (2/2) – ................ 29
7-10. Printed Wiring Board  – VIDEO Board – ....................... 30
7-11. Printed Wiring Boards

– CD MOTOR/SENSOR Section – ................................ 32

7-12. Schematic Diagram

– CD MOTOR/SENSOR Section – ................................ 33

7-13. Printed Wiring Board  – AUDIO Board – ...................... 34
7-14. Schematic Diagram  – AUDIO Board – ......................... 35
7-15. Printed Wiring Board  – LEAF SW Board – .................. 36
7-16. Schematic Diagram  – LEAF SW Board – ..................... 36
7-17. Printed Wiring Board  – MAIN Board – ........................ 37
7-18. Schematic Diagram  – MAIN Board (1/2) – .................. 38
7-19. Schematic Diagram  – MAIN Board (2/2) – .................. 39
7-20. Printed Wiring Board  – POWER Board – ..................... 40
7-21. Schematic Diagram  – POWER Board – ........................ 41
7-22. Printed Wiring Boards  – PANEL Section – .................. 42
7-23. Schematic Diagram  – PANEL Section – ....................... 43
7-24. IC Pin Function Description ........................................... 48

................................................ 57

............................... 64

3

The laser diode in the optical pick-up block may suffer electro-
static break-down because of the potential difference generated
by the charged electrostatic load, etc. on clothing and the human
body.
During repair, pay attention to electrostatic break-down and also
use the procedure in the printed matter which is included in the
repair parts.
The flexible board is easily damaged and should be handled with
care.

The laser beam on this model is concentrated so as to be focused
on the disc reflective surface by the objective lens in the optical
pick-up block. Therefore, when checking the laser diode emis-
sion, observe from more than 30 cm away from the objective lens.

• Keep the temperature of the soldering iron around 270 ˚C dur-

ing repairing.

• Do not touch the soldering iron on the same conductor of the

circuit board (within 3 times).

• Be careful not to apply force on the conductor when soldering

or unsoldering.

CAUTION

Use of controls or adjustments or performance of procedures
other than those specified herein may result in hazardous ra-
diation exposure.

This appliance is classified as a CLASS 1 LASER product.
The CLASS 1 LASER PRODUCT MARKING is located on
the rear exterior.

Laser component in this product is capable of emitting radiation
exceeding the limit for Class 1.

The following caution label is located inside the unit.

!   KERÜLJE  A  BESUGÁRZÁST! 

This unit is equipped with a self-diagnosis function.
The function is used for diagnosing the conditions of the circuits
of the VIDEO board.
The circuits can be determined if normal or abnormal by the light-
ing of D502 of the VIDEO board.

Lighting of D502
When lit

: Operates normally

Blinks repeatedly: The circuit may be faulty.

[VIDEO Board] (Side B)

CN501

SL501

SL502

SL503

CN502

IC505

D502

• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be dam-

aged by heat.

4

• As this set has not own power supply, it does not operate inde-

pendently. Therefore, during servicing, connect it to the Pre-
Main amplifier and Tuner Unit (STR-NX300) of MHC-
NX300AV.

If STR-NX300 are not available, use the Power Feed Jig (PFJ-
1) and Relay Connector Jig.
In this case, after turn on the POWER switch on the Power Feed
Jig, supply power with the following methods.

[Note]
The Power Feed Jig (PFJ-1) is deficient in power to drive this
set.
The details are listed below. For the items with 

×

 marking, use

the STR-NX300.

Operation check

Characteristic measurement

Tape Deck

a

f*1

CD section

CD

a

×

SVCD

×

×

*1: Possible when a flat cable between CN111 (MAIN board) and

CN502 (VIDEO board) is disconnected.

Procedure:
1. Press three buttons of

s

(DECK B),

A

(DISC 1),

and

s

(CD) simultaneously.

2. The

G

(CD) and

S

(CD) LEDs blink, and then pressing

G

(CD),

G

/

g

(DECK A), or

G

/

g

(DECK B) button can

make each play possible.

3. Also, the other functions are enabled by pressing two buttons

simultaneously.
A combination of respective functions and buttons is as fol-
lows.

function

button

CD AMS –

s

(DECK A),

S

(CD)

AMS +

s

(DECK A),

s

(CD)

FR

s

(DECK B),

S

(CD)

FF

s

(DECK B),

s

(CD)

Deck-A REW/AMS –

s

(CD),

g

(DECK A)

FF/AMS +

s

(CD),

G

(DECK A)

Deck-B REW/AMS –

s

(CD),

g

(DECK B)

FF/AMS +

s

(CD),

G

(DECK B)

Set

SYSTEM CONTROL terminal

SYSTEM CONTROL terminal

Connector cable (19P)

Pre-Main AMP
and Tuner Unit

AC IN

Power feed jig
(PFJ-1)

Connector cable (17P) of
attachment to power feed jig

Relay connector jig
(J-2501-174-A)

CD/TC signal
change switch

CN101 (19P)
SYSTEM CONTROL
terminal

system cable

Exclusive cable (15P)

P707, P909

Set

CDP/TC

ST