HCD-GX25, MHC-GX25 - Sony Audio Service Manual (repair manual)

1

Model Name Using Similar Mechanism

NEW

CD

CD Mechanism Type

CDM74F-K6BD72

Section

Optical Pick-up Name

KSM-213DCP

Tape deck Model Name Using Similar Machanism

NEW

Section

Tape Transport Mechanism Type

CWM43FF-05

US Model

Continuous RMS power output (reference)

120+120 watts (6 ohms at
1 kHz, 10% THD)

Total harmonic distortion

less than 0.07%
(6 ohms at 1 kHz, 60W)

Inputs
GAME INPUT AUDIO L/R (phono jacks):

voltage 250 mV,
impedance 47 kilohms

GAME INPUT VIDEO (phono jack):

1 Vp-p, 75 ohms

Outputs
PHONES (stereo mini jack):

accepts headphones of
8 ohms or more

VIDEO OUT (phono jack):

max. output level 1 Vp-p,
unbalanced, Sync negative,
load impedance 75 ohms

SPEAKER:

accepts impedance of 6 to
16 ohms

System

Compact disc and digital
audio system

Laser

Semiconductor laser
(

λ=780 nm)

Emission duration:
continuous

Frequency response

2 Hz – 20 kHz (±0.5 dB)

Wavelength

780 – 790 nm

Signal-to-noise ratio

More than 90 dB

Dynamic range

More than 90 dB

Recording system

4-track 2-channel stereo

Frequency response

50 – 13,000 Hz (±3 dB),
using Sony TYPE I
cassette

2003C0400-1

© 2003. 03

– Continued on next page –

• HCD-GX25 is the tuner, deck, CD

and amplifier section in MHC-
GX25.

2

0

0

FM stereo, FM/AM superheterodyne tuner

Tuning range

87.5 – 108.0 MHz

Antenna

FM lead antenna

Antenna terminals

75 ohm unbalanced

Intermediate frequency 10.7 MHz

Tuning range

530 – 1,710 kHz (with the tuning

interval set at 10 kHz)

Antenna

AM loop antenna

Antenna terminals

External antenna terminal

Intermediate frequency 450 kHz

Power requirements

120 V AC, 60 Hz

Power consumption

120 watts

Dimensions (w/h/d)

Approx. 280 

× 325 × 407 mm

Mass

Approx. 8.5 kg

Supplied accessories:

AM loop antenna (1)
Remote Commander (1)
Batteries (2)
FM lead antenna (1)
Speaker pads (8)

To Exposed Metal
Parts on Set

0.15µF

1.5k

Ω

AC
voltmeter
(0.75V)

Earth Ground

After correcting the original service problem, perform the following
safety check before releasing the set to the customer:
Check the antenna terminals, metal trim, “metallized” knobs, screws,
and all other exposed metal parts for AC leakage. Check leakage as
described below.

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 microamperes).
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 low-voltage scale. The
Simpson 250 and Sanwa SH-63Trd are examples of a passive
VOM that is suitable. Nearly all battery operated digital
multimeters that have a 2V AC range are suitable. (See Fig. A)

3

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

The laser diode in the optical pick-up block may suffer electrostatic
breakdown 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 emission,
observe from more than 30 cm away from the objective lens.

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

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

damaged by heat.

• Keep the temperature of soldering iron around 270°C during

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.

– BACK PANEL –

PARTS No.

US models

4-244-697-01

4

Main Unit ................................................................................ 5
Remote Control ....................................................................... 6

2-1.   Case (Top) ........................................................................... 8
2-2.   CD Door .............................................................................. 8
2-3.   Front Panel Section ............................................................. 9
2-4.   CD Mechanism Block ....................................................... 10
2-5.   Tape Mechanism Deck ...................................................... 10
2-6.   Panel Board, 1 Stream Led Board, Remote Board ............ 11
2-7.   Game Jack Board, H/P Jack Board ................................... 11
2-8.   Back Panel Section ............................................................ 12
2-9.   Main Board ....................................................................... 12
2-10. Amp Board ........................................................................ 13
2-11. Driver Board, Sw Board .................................................... 13
2-12. CD Block Assy .................................................................. 14
2-13. Sensor Board ..................................................................... 14
2-14. Motor (TB) Board ............................................................. 15
2-15. Motor (LD) Board ............................................................. 15
2-16. Optical Pick-up ................................................................. 16

3-1.   IC Pin Description ............................................................. 17
3-2.   Circuit Boards Location .................................................... 19
3-3.   Printed Wiring Boards –CD Mechanism Section (1/2)– ... 21
3-4.   Printed Wiring Boards –CD Mechanism Section (2/2)– ... 22
3-5.   Schematic Diagram –CD Mechanism Section– ................ 23
3-6.   Printed Wiring Boards –Main Section– ............................ 24
3-7.   Schematic Diagram –Main Section (1/3)– ........................ 25
3-8.   Schematic Diagrams –Main Section (2/3)– ...................... 26
3-9.   Schematic Diagram –Main Section (3/3)– ........................ 27
3-10. Printed Wiring Boards –Panel Section– ............................ 28
3-11. Schematic Diagram –Panel Section– ................................ 29
3-12. Printed Wiring Board –Power Amp Section– ................... 30
3-13. Schematic Diagram –Power Amp Section (1/2)– ............. 31
3-14. Schematic Diagram –Power Amp Section (2/2)– ............. 32
3-15. Printed Wiring Board –Transformer Section– .................. 33
3-16. Schematic Diagram –Transformer Section– ..................... 34
3-17. IC Block Diagrams ............................................................ 35

4-1.   Main Section ..................................................................... 37
4-2.   Front Panel Section ........................................................... 38
4-3.   Main Board Section .......................................................... 39
4-4.   CD Mechanism Deck Section (1) ..................................... 40
4-5.   CD Mechanism Deck Section (2) ..................................... 41
4-6.   Optical Pick-up Section ..................................................... 42

........................................ 43