CMT-EH55DAB, HCD-EH55DAB - Sony Audio Service Manual (repair manual)

2008G05-1

© 

2008.07

•  HCD-EH55DAB is the amplifi er, USB, CD player, 

tape deck and tuner section in CMT-EH55DAB.

CD 
Section

Model Name Using Similar Mechanism

HCD-EH15

Base Unit Name

BU-K8BD90-WOD

Optical Pick-up Block Name

KSM-213CDP

TAPE
Section

Model Name Using Similar Mechanism

HCD-EH15

Tape Transport Mechanism Type

MF-EH10

DIN power output (rated):
4 + 4 watts (4 ohms at 1 kHz, DIN)
Continuous RMS power output
(reference): 5 + 5 watts (4 ohms at
1 kHz, 10% THD)
Music power output (reference):
7 + 7 watts (4 ohms at 1 kHz, 10% 
THD)

Inputs:

AUDIO IN (stereo mini jack):
voltage 800 mV, impedance
47 kilohms

 (USB) port: Type A, maximum

current 500 mA

Outputs:

PHONES (stereo mini jack): accepts
headphones of 8 ohms or more
SPEAKER: accepts impedance of
4 ohms

Supported bit rate

MP3 (MPEG 1 Audio Layer-3):
32 — 320 kbps, VBR

Sampling frequencies

MP3 (MPEG 1 Audio Layer-3):
32/44.1/48 kHz

System: Compact disc and digital audio
system
Laser Diode Properties

Emission Duration: Continuous
Laser Output*: Less than 44.6μW

*

at a distance of 200mm from the

This output is the value measurement

objective lens surface on the Optical
Pick-up Block with 7mm aperture.

Frequency response: 20 Hz — 20 kHz
Signal-to-noise ratio: More than 90 dB
Dynamic range: More than 90 dB

Recording system: 4-track 2-channel, stereo

FM/DAB stereo tuner

DAB tuner section:

Frequency range*
Band-III: 174.928 (5A) — 239.200 
(13F) MHz

* For details, see “DAB frequency table”

(page 31).

Antenna: FM/DAB lead antenna
FM tuner section:

Tuning range:

87.5 — 108.0 MHz (50 kHz step)

Antenna: FM/DAB lead antenna
Intermediate frequency: 10.7 MHz

DAB frequency table (Band-III)

174.928 MHz 5A

209.936 MHz 10A

176.640 MHz 5B

211.648 MHz 10B

178.352 MHz 5C

213.360 MHz 10C

180.064 MHz 5D

215.072 MHz 10D

181.936 MHz 6A

216.928 MHz 11A

183.648 MHz 6B

218.640 MHz 11B

185.360 MHz 6C

220.352 MHz 11C

187.072 MHz 6D

222.064 MHz 11D

188.928 MHz 7A

223.936 MHz 12A

190.640 MHz 7B

225.648 MHz 12B

192.352 MHz 7C

227.360 MHz 12C

194.064 MHz 7D

229.072 MHz 12D

195.936 MHz 8A

230.784 MHz 13A

197.648 MHz 8B

232.496 MHz 13B

199.360 MHz 8C

234.208 MHz 13C

201.072 MHz 8D

235.776 MHz 13D

202.928 MHz 9A

237.488 MHz 13E

204.640 MHz 9B

239.200 MHz 13F

206.352 MHz 9C

208.064 MHz 9D

* Frequencies are displayed to two decimal

places on this system.

Power requirements:

230 V AC, 50/60 Hz

Power consumption: 29 watts
Dimensions (w/h/d) (excl. speakers):
Approx. 155 × 241 × 224.6 mm
Mass (excl. speakers): Approx. 2.2 kg

Design and specifications are subject to
change without notice.

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

3

  ..................................................................   4

3-1.   Disassembly ....................................................................   6
3-2.   Rear Cabinet Block .........................................................   6
3-3.   Front Cabinet Block, Top Cabinet Block, 
 MAIN 

Board 

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

7

3-4.   MF-EH10 (Tape Mechanism Deck), Cassette Lid ..........   7
3-5.   Base Unit Block (BU-K8BD90-WOD) ..........................   8
3-6.   Optical Pick-Up Block (KSM-213CDP) ........................   8

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

9

 ......................   10

........................  10

7-1.  Block Diagram - CD SERVO Section - ..........................   12
7-2.  Block Diagram - MAIN Section - ...................................   13
7-3. Block 

Diagram 

 

- PANEL, POWER SUPPLY Section - ...........................   14

7-4.  Printed Wiring Board - CD Board - ................................   16
7-5.  Schematic Diagram - CD Board - ...................................   17
7-6.  Printed Wiring Board - USB Board - ..............................   18
7-7.  Schematic Diagram - USB Board - .................................   19
7-8.  Printed Wiring Board - PANEL Board - .........................   20
7-9.  Schematic Diagram - PANEL Board - ............................   21
7-10.  Printed Wiring Board - MAIN Board - ...........................   22
7-11.  Schematic Diagram - MAIN Board (1/3) - .....................   23
7-12.  Schematic Diagram - MAIN Board (2/3) - .....................   24
7-13.  Schematic Diagram - MAIN Board (3/3) - .....................   25
7-14.  Printed Wiring Board - PT-VBUS Board - .....................   26
7-15.  Schematic Diagram - PT-VBUS Board - ........................   26

8-1. Overall 

Section 

...............................................................  36

8-2.  Front Cabinet Section .....................................................   37
8-3.  Top Cabinet Section ........................................................   38
8-4.  Base Unit Section (BU-K8BD90-WOD) ........................   39

  ..............................   40

NOTES  ON  CHIP  COMPONENT  REPLACEMENT
• 

Never reuse a disconnected chip component.

• 

Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.

COMPONENTS  IDENTIFIED  BY  MARK  0  OR  DOTTED  LINE  
WITH  MARK  0  ON  THE  SCHEMATIC  DIAGRAMS  AND  IN  
THE  PARTS  LIST  ARE  CRITICAL  TO  SAFE  OPERATION.
REPLACE  THESE  COMPONENTS  WITH  SONY  PARTS 

This appliance is classifi ed as 
a CLASS 1 LASER product.
This marking is located on the 
rear or bottom exterior.

CAUTION
Use of controls or adjustments or performance of procedures 
other than those specifi ed herein may result in hazardous radia-
tion exposure.

The laser diode in the optical pick-up block may suffer electrostat-
ic 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 fl exible board is easily damaged and should be handled with 
care.

NOTES  ON  LASER  DIODE  EMISSION  CHECK
The laser beam on this model is concentrated so as to be focused 
on the disc refl ective surface by the objective lens in the optical 
pickup block. Therefore, when checking the laser diode emission, 
observe from more than 30 cm away from the objective lens.

UNLEADED  SOLDER
Boards requiring use of unleaded solder are printed with the lead-
free mark (LF) indicating the solder contains no lead.
(Caution:  Some printed circuit boards may not come printed with 

the lead free mark due to their particular size)

Unleaded solder has the following characteristics.
•  Unleaded solder melts at a temperature about 40 °C higher 

than ordinary solder.

 

Ordinary soldering irons can be used but the iron tip has to be 
applied to the solder joint for a slightly longer time.

 

Soldering irons using a temperature regulator should be set to 
about 350 °C.
Caution: The printed pattern (copper foil) may peel away if 

the heated tip is applied for too long, so be careful!

• Strong 

viscosity

 

Unleaded solder is more viscous (sticky, less prone to fl ow) 
than ordinary solder so use caution not to let solder bridges 
occur such as on IC pins, etc.

•  Usable with ordinary solder
 

It is best to use only unleaded solder but unleaded solder may 
also be added to ordinary solder.

LASER  DIODE  AND  FOCUS  SEARCH  OPERATION  
CHECK
During normal operation of the equipment, emission of the laser 
diode is prohibited unless the upper lid is closed while turning on 
the SW750. (push switch type)
The following checking method for the laser diode is operable.
• Method
  Emission of the laser diode is visually checked.

1.  Open the upper lid.
2.  Push the SW750 as shown in Fig.1.

  Note: Do not push the detection lever strongly, or it may be bent or dam-

aged.

3.  Check the object lens for confi rming normal emission of the 

laser diode. If not enitting, there is a trouble in the automatic 
power control cirsuit or the optical pick-up.

 

In this operation, the object lens will move up and down 2 
times along with inward motion for the focus search.

This section is extracted 
from instruction manual.

This manual mainly explains operations using the remote, but the same operations can also be performed using the buttons on the unit having the 
same or similar names.

Open the tape 
section lid.

/ (power) button

Press to turn on the  system.

Press to select a track or file.

/ (go back/go forward)
button

Unit: TUNING +/−  (tuning) 
button
Remote: +/−  (tuning) button

Press to tune in the desired station.

Press to find a point in a track or file.

/ (rewind/fast forward)
button

DAB

Press to select the DAB function.

DAB AUTO SCAN

Press to run the DAB Automatic Scan.

Press to select the sound effect.

Sound buttons
Unit: DSGX button
Remote: EQ button

 PUSH OPEN/CLOSE

Press to open or close the CD 
compartment.

Remote sensor

Playback buttons and function
buttons
Unit: USB  (play/pause)
button

Press to select the  USB function.
Press to start or pause playback of an
optional USB device.

Remote: USB button

Press to select the  USB function.

Unit: CD  (play/pause)
button

Press to select the CD function.
Press to start or pause playback of a disc.

Remote: CD button

Press to select the CD function.

Remote:  (play) button,

 (pause) button

Press to start or pause playback.

TUNER/BAND button

Press to select the TUNER function.
Press to select DAB or FM reception
mode.

FUNCTION button

Press to select the function.

 (stop) button

Press to stop playback.

 (USB) port

Connect to an optional USB device.

Unit: VOLUME control
Remote: VOLUME +/−  button

Turn or press to adjust the volume.

 (record) button,  (play)
button, / (rewind/fast
forward) button,   (stop/
eject) button,  (pause) button

Press to operate the tape functions.

PHONES jack

Connect the headphones.

AUDIO IN jack

Connect to an optional audio

Lights up when the system is turned off.

component.

STANDBY indicator

CLOCK/TIMER SELECT button
CLOCK/TIMER SET button

Press to set the clock and the Play Timer.

REPEAT/FM MODE button

Press to listen to a disc or USB device
repeatedly. Or press to listen to a single
track/file or all tracks/files in a folder (for
USB devices only) repeatedly.
Press to select the FM reception mode
(monaural or stereo).

ENTER button

Press to enter the settings.

R

RB

RT

RE

RG

RH

RI

RK

RL

X

XB

XT

XE

XG

RM

 +/−  (select folder) button

Press to select a folder.

Battery compartment lid 

CLEAR button

Press to delete a pre-programmed track
or file.

TUNER MEMORY button

Press to preset the radio station.

PLAY MODE/TUNING MODE 
button

Press to select the play mode of a CD or
MP3 disc.
Press to select the tuning mode.

DISPLAY button

Press to change the  information on the
display.

SLEEP button

Press to set the Sleep Timer.