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US Model

Canadian Model

HCD-DX155/DX255

E Model

Australian Model

HCD-DX155

2007J16-1
© 2007.10

HCD-DX155/DX255 are the amplifier, DVD/CD
and tuner section in DAV-DX155/DX255.

Model Name Using Similar Mechanism

HCD-DX150

Mechanism Type

CDM81C-DVBU101

Optical Pick-up Name

KHM-310CAB

This system incorporates with Dolby*

1

 Digital and Dolby Pro Logic (II)

adaptive matrix surround decoder and the DTS*

2

  Digital Surround

System.
*1 Manufactured under license from Dolby Laboratories.

“Dolby,” “Pro Logic,” and the double-D symbol are trademarks of
Dolby Laboratories.

*2 Manufactured under license from Digital Theater Systems, Inc.

“DTS” and “DTS Digital Surround” are trademarks of Digital
Theater Systems, Inc.

— Continued on next page —

Photo : HCD-DX255

POWER OUTPUT AND 
TOTAL HARMONIC 
DISTORTION 
(FTC Output Power): 

FL/FR/LS/RS/C: 84 W/ch 
3 ohm at 170 - 20,000 Hz,
0.7 % THD 
SW: 80 W 3 ohm at 40 - 
170 Hz, 0.7 % THD

POWER OUTPUT AND 
TOTAL HARMONIC 
DISTORTION 
(FTC Output Power): 

FL/FR/LS/RS/C: 84 W/ch 
3 ohm at 170 - 20,000 Hz,
0.7 % THD 
SW: 160 W 1.5 ohm at 40 - 
170 Hz, 0.7 % THD

US models:
Surround mode (reference) RMS output power, 10 % 

THD
Front: 142 W + 142 W 
(with SS-TS52)

Center*: 142 W
(with SS-CT51)
Surround*: 142 W + 142 
W
(with SS-TS51)
Subwoofer*: 140 W
(with SS-WS52)

Mexican and other models:
Stereo mode (rated)

108 W + 108 W (3 ohms at 
1 kHz, 1 % THD)

Surround mode (reference) RMS output power, 10 % 

THD
Front: 142 W + 142 W 
(with SS-TS52)

Center*: 142 W
(with SS-CT51)
Surround*: 142 W + 142 
W
(with SS-TS51)
Subwoofer*: 140 W
(with SS-WS52)

Latin American models:
Stereo mode (rated)

100 W + 100 W (3 ohms at 
1 kHz, 1 % THD)

Surround mode (reference) RMS output power, 10 % 

THD

Front: 133 W + 133 W 
(with SS-TS52)
Center*: 133 W
(with SS-CT51)
Surround*: 133 W + 133 
W
(with SS-TS51)
Subwoofer*: 135 W
(with SS-WS52)

US models:
Surround mode (reference) RMS output power, 10 % 

THD
Front: 143 W + 143 W 
(with SS-TS52)
Center*: 143 W
(with SS-CT51)
Surround*: 143 W + 143 
W
(with SS-TS51)
Subwoofer*: 285 W
(with SS-WS52B)

2

DX155 : US model

2-661-240-0

[]

DX255 : US model

2-661-240-1

[]

DX155 : SP model

2-661-240-2

[]

DX155 : MX model

2-661-240-3

[]

DX155 : CND model

2-661-240-4

[]

DX255 : CND model

2-661-240-5

[]

DX155 : AUS model

2-661-240-6

[]

DX155 : E3 model

2-661-240-7

[]

• Abbreviation

AUS

: Australian model

CND

: Canadian model

E3

: 240V AC area in E model

MX

: Mexican model

SP

: Singapore model

Inputs
TV/VCR (AUDIO IN)

Sensitivity: 450/250 mV

AUDIO IN/MIC

Sensitivity: 250/125 mV

Outputs (Analog)
Phones

Accepts low-and high-
impedance headphones.

Laser

 

Semiconductor laser

(DVD: 

λ = 650 nm)

(CD: 

λ = 790 nm)

Emission duration: 
continuous

Signal format system
North American, Latin, and Mexican models:

NTSC 

Other models:

NTSC/PAL

System

PLL quartz-locked digital 
synthesizer system

FM tuner section
Tuning range 
North American models:

87.5 – 108.0 MHz 
(100 kHz step)

Other models:

87.5 – 108.0 MHz 
(50 kHz step)

Antenna (aerial)

FM wire antenna (aerial)

Antenna (aerial) terminals 75 ohms, unbalanced
Intermediate frequency

10.7 MHz

AM tuner section
Tuning range 
Middle Eastern models:

531-1,602 kHz (with the 
interval set at 9 kHz)

Asian models: 

531-1,602 kHz (with the 
interval set at 9 kHz)
530-1,710 kHz (with the 
interval set at 10 kHz)

North American and Latin American models:

530-1,710 kHz (with the 
interval set at 10 kHz)
531-1,710 kHz (with the 
interval set at 9 kHz)

Antenna (aerial)

AM loop antenna (aerial)

Intermediate frequency

450 kHz

Outputs

V
S VIDEO:
Y: 1 Vp-p 75 ohms
C: 0.286 Vp-p 75 ohms

IDEO: 1 Vp-p 75 ohms

COMPONENT:
Y: 1 Vp-p 75 ohms

P

B

/C

B

, P

R

/C

R

: 0.7 Vp-p 

75 ohms

Other models:
Stereo mode (rated)

108 W + 108 W (3 ohms at 
1 kHz, 1 % THD)

Surround mode (reference) RMS output power, 10 % 

THD
Front: 143 W + 143 W 
(with SS-TS52)
Center*: 143 W
(with SS-CT51)
Surround*: 143 W + 143 
W
(with SS-TS51)
Subwoofer*: 285 W
(with SS-WS52B)

Power requirements 
North American and Mexican models:

120 V AC, 60 Hz

Latin American models:

110 – 240 V AC, 50/60 Hz

Other models:

220 – 240 V AC, 50/60 Hz

Power consumption

On: 140 W (Latin 
American models of
DX155), 150 W 
(Mexican and other models 
of DX155), 160 W (DX255)
Standby: 0.3 W (at the 
Power Saving mode) 

Dimensions (approx.)

430 

× 86 × 418 mm 

(17 

× 3 

1

/

2

 

× 16 

3

/

4

 inches) 

(w/h/d) incl. projecting 
parts

Mass (approx.)

5.0 kg (11 lb 1 oz)

Design and specifications are subject to change 
without notice.

COAXIAL

AM

FM75

SPEAKER

FRONT R

FRONT L

SUR R

SUR L

CENTER

WOOFER

COMPONENT VIDEO OUT

TV/VCR

MONITOR OUT

ANTENNA

(DVD ONLY )

Y

P

B

/C

B

P

R

/C

R

R

L

AUDIO IN

VIDEO

(DVD ONLY )

S VIDEO

Parts No.

3

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 viscou-s (sticky, less prone to flow)
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.

• Never reuse a disconnected chip component.

• Notice that the minus side of a tantalum capacitor may be

damaged by heat.

• Keep the temperature of the 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.

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

This appliance is classified as
a CLASS 1 LASER product.
This marking is located on
the bottom exterior.

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

0

0

0

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 2 V AC range are suitable.  (See
Fig. A)

1.5 k

Ω

0.15 

µ

F

AC
voltmeter
(0.75 V)

To Exposed Metal
Parts on Set

Earth Ground

4

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

5

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

8

3-1.

Disassembly Flow ........................................................... 11

3-2.

Case, Front Panel Assy .................................................... 12

3-3.

FL Board, SW Board ....................................................... 13

3-4.

JACK Board, LED Board ................................................ 13

3-5.

I/O Board, Tuner .............................................................. 14

3-6.

SPEAKER Board, D.C. Fan ............................................ 14

3-7.

MAIN Board .................................................................... 15

3-8.

POWER Board ................................................................ 16

3-9.

DVD Mechanism Deck (CDM81C-DVBU101) ............. 17

3-10. Tray .................................................................................. 18
3-11. MOTOR Board M761 (LD/ST Motor),

M762 (BU U/D Motor) ................................................... 18

3-12. Base Unit (DVBU101) .................................................... 19
3-13. Optical Pick-up (KHM-310CAB) ................................... 19
3-14. Gear (Sub Tray 1), Gear (Sub Tray 2) ............................. 20
3-15. Lever Assy ....................................................................... 20
3-16. Stocker Section ................................................................ 21
3-17. Cam (Stocker) .................................................................. 21
3-18. Gear (Stocker 3) .............................................................. 22
3-19. Rotary Encoder (MD) ...................................................... 22
3-20. Gear (BU2) ...................................................................... 23

............................................................... 24

............................. 28

6-1.

Block Diagram  – RF Section – ....................................... 30

6-2.

Block Diagram  – AMP Section – ................................... 31

6-3.

Block Diagram  – AUDIO Section – ............................... 32

6-4.

Block Diagram  – VIDEO Section – ............................... 33

6-5.

Block Diagram  – POWER Section – .............................. 34

6-6.

Printed Wiring Board – MAIN Board (Side A) – ............ 35

6-7.

Printed Wiring Board – MAIN Board (Side B) – ............ 36

6-8.

Schematic Diagram  – MAIN Board (1/10) – ................. 37

6-9.

Schematic Diagram  – MAIN Board (2/10) – ................. 38

6-10. Schematic Diagram  – MAIN Board (3/10) – ................. 39
6-11. Schematic Diagram  – MAIN Board (4/10) – ................. 40
6-12. Schematic Diagram  – MAIN Board (5/10) – ................. 41
6-13. Schematic Diagram  – MAIN Board (6/10) – ................. 42
6-14. Schematic Diagram  – MAIN Board (7/10) – ................. 43
6-15. Schematic Diagram  – MAIN Board (8/10) – ................. 44
6-16. Schematic Diagram  – MAIN Board (9/10) – ................. 45
6-17. Schematic Diagram  – MAIN Board (10/10) – ............... 46
6-18. Printed Wiring Board – I/O Board – ............................... 47
6-19. Schematic Diagram  – I/O Board – ................................. 48
6-20. Printed Wiring Boards – PANEL Section – ..................... 49
6-21. Schematic Diagram  – PANEL Section  – ....................... 50
6-22. Printed Wiring Board – SPEAKER Board – ................... 51
6-23. Schematic Diagram  – SPEAKER Board  – .................... 51
6-24. Printed Wiring Boards  – CD Mechanism Section – ....... 52
6-25. Schematic Diagram  – CD Mechanism Section  – .......... 53
6-26. Printed Wiring Board – POWER Board – ....................... 54
6-27. Schematic Diagram  – POWER Board  – ........................ 55

7-1.

Overall Section ................................................................ 67

7-2.

Front Panel Section ......................................................... 68

7-3.

Chassis Section ................................................................ 69

7-4.

DVD Mechanism Deck Section-1
(CDM81C-DVBU101) .................................................... 70

7-5.

DVD Mechanism Deck Section-2
(CDM81C-DVBU101) .................................................... 71

7-6.

DVD Mechanism Deck Section-3
(CDM81C-DVBU101) .................................................... 72

7-7.

Base Unit (DVBU101) .................................................... 73

.................................. 74