SERVICE MANUAL

MODEL : LH-T250(SC)

DVD/CD RECEIVER
SERVICE MANUAL

LHS-25SCS, LHS-25SCW

MODEL : LH-T250(SC)
LHS-25SCS, LHS-25SCW

[CONTENTS]
SECTION 1. GENERAL
SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

SECTION 2. AUDIO PART

AUDIO TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20
PRINTED CIRCUIT DIARGAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22

SECTION 3. DVD & AMP PART

ELECTRICAL TROUBLESHOOTING GUIDE

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1

DVD PART SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-22

SECTION 4. EXPLODED VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1

SECTION 5. SPEAKER PART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1
SECTION 6. REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1

1-1

SECTION 1. GENERAL
SERVICING PRECAUTIONS
NOTES REGARDING HANDLING OF THE PICK-UP
1. Notes for transport and storage
1) The pick-up should always be left in its conductive bag until immediately prior to use.
2) The pick-up should never be subjected to external pressure or impact.

Storage in conductive bag

Drop impact

2. Repair notes
1) The pick-up incorporates a strong magnet, and so should never be brought close to magnetic materials.
2) The pick-up should always be handled correctly and carefully, taking care to avoid external pressure and
impact. If it is subjected to strong pressure or impact, the result may be an operational malfunction and/or
damage to the printed-circuit board.
3) Each and every pick-up is already individually adjusted to a high degree of precision, and for that reason
the adjustment point and installation screws should absolutely never be touched.
4) Laser beams may damage the eyes!
Absolutely never permit laser beams to enter the eyes!
Also NEVER switch ON the power to the laser output part (lens, etc.) of the pick-up if it is damaged.

NEVER look directly at the laser beam, and dont let

contact fingers or other exposed skin.
5) Cleaning the lens surface
If there is dust on the lens surface, the dust should be cleaned away by using an air bush (such as used
for camera lens). The lens is held by a delicate spring. When cleaning the lens surface, therefore, a cotton swab should be used, taking care not to distort this.

Pressure
Magnet

Pressure

How to hold the pick-up

Cotton swab

Conductive Sheet
6) Never attempt to disassemble the pick-up.
Spring by excess pressure. If the lens is extremely dirty, apply isopropyl alcohol to the cotton swab.
(Do not use any other liquid cleaners, because they will damage the lens.) Take care not to use too much
of this alcohol on the swab, and do not allow the alcohol to get inside the pick-up.

1-2

NOTES REGARDING COMPACT DISC PLAYER REPAIRS

1. Preparations
1) Compact disc players incorporate a great many ICs as well as the pick-up (laser diode). These components
are sensitive to, and easily affected by, static electricity. If such static electricity is high voltage, components
can be damaged, and for that reason components should be handled with care.
2) The pick-up is composed of many optical components and other high-precision components. Care must be
taken, therefore, to avoid repair or storage where the temperature of humidity is high, where strong magnetism is present, or where there is excessive dust.

2. Notes for repair

1) Before replacing a component part, first disconnect the power supply lead wire from the unit
2) All equipment, measuring instruments and tools must be grounded.
3) The workbench should be covered with a conductive sheet and grounded.
When removing the laser pick-up from its conductive bag, do not place the pick-up on the bag. (This is
because there is the possibility of damage by static electricity.)
4) To prevent AC leakage, the metal part of the soldering iron should be grounded.
5) Workers should be grounded by an armband (1M )
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent
static electricity changes in the clothing to escape from the armband.
7) The laser beam from the pick-up should NEVER be directly facing the eyes or bare skin.
Armband

Resistor
(1 Mohm)
Resistor
(1 Mohm)

Conductive
Sheet

1-3

ESD PRECAUTIONS
Electrostatically Sensitive Devices (ESD)
Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components
commonly are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated
circuits and some field-effect transistors and semiconductor chip components. The following techniques should
be used to help reduce the incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off
any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a
commercially available discharging wrist strap device, which should be removed for potential shock reasons
prior to applying power to the unit under test.
2. After removing an electrical assembly equipped with ESD devices, place the assembly on a conductive surface
such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ESD devices.
4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static" can
generate electrical charges sufficient to damage ESD devices.
5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ESD
devices.
6. Do not remove a replacement ESD device from its protective package until immediately before you are
ready to install it. (Most replacement ESD devices are packaged with leads electrically shorted together by
conductive foam, aluminum foil or comparable conductive materials).
7. Immediately before removing the protective material from the leads of a replacement ESD device, touch the
protective material to the chassis or circuit assembly into which the device will by installed.
CAUTION : BE SURE NO POWER IS APPLIED TO THE CHASSIS OR CIRCUIT, AND OBSERVE ALL OTHER
SAFETY PRECAUTIONS.
8. Minimize bodily motions when handing unpackaged replacement ESD devices. (Otherwise harmless motion
such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient to damage an ESD device).

CAUTION. GRAPHIC SYMBOLS

THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS
INTENDED TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED
DANGEROUS VOLTAGE THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF
ELECTRIC SHOCK.

THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE

SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE
LITERATURE.

1-4

SPECIFICATIONS
GENERAL
Power supply
Power consumption
Weight
External dimensions (W x H x D)
Operating conditions Temperature:
Operating humidity

Refer to main label

Refer to main label
2.5 kg
360 x 56 x 310 mm
5C to 35C, Operation status: Horizontal
5% to 85%

CD/DVD
Laser
Signal system
Frequency response (audio)
Signal-to-noise ratio (audio)
Dynamic range (audio)
Harmonic distortion (audio)
Video output
TUNER
FM
Tuning Range
Intermediate Frequency
Signal-to Noise Ratio
Frequency Response
AM [MW]
Tuning Range
Intermediate
AMPLIFIER
Surround mode
(* Depending on the sound mode
settings and the source, there
may be no sound output.)

Outputs

Semiconductor laser, wavelength 650 nm

PAL 625/50, NTSC 525/60
140 Hz to 20 kHz
More than 75 dB (1 kHz, NOP-3dB, 20 kHz LPF/A-Filter)
More than 80 dB
0.5 % (1 kHz, at 12W position) (20 kHz LPF/A-Filter)
1.0 V (p-p), 75 , negative sync., RCA jack

87.5 - 108.0 MHz or 65.0 - 74.0 MHz, 87.5 - 108.0 MHz

10.7 MHz
60 dB (Mono)
140 - 10,000 Hz
522 - 1,620 kHz or 520 - 1,720 kHz
Frequency 450 kHz

Front: 30W + 30W (THD 10 %)

Center*: 30W
Surround*: 30W + 30W (6 at 1 kHz, THD 10 %)
Subwoofer*: 70W (8 at 30 Hz, THD 10 %)
MONITOR
MIC Jacks (3.5mm) (KARAOKE MODEL ONLY))

SPEAKERS
Type
Impedance
Frequency Response
Sound Pressure Level
Rated Input Power
Max. Input Power
Net Dimensions (W x H x D)
Net Weight

Satellite Speaker (LHS-25SCS)

1 Way 1 Speaker
6
160 - 20,000 Hz
84 dB/W (1m)
30W
60W
92 x 115 x 80 mm
0.5 kg
1-5

Passive Subwoofer (LHS-25SCW)

1 Way 1 Speaker
8
65 - 1,500 Hz
82 dB/W (1m)
70W
140W
160 x 350 x 280 mm
3.18 kg

SECTION 2. AUDIO PART

AUDIO TROUBLESHOOTING GUIDE
1. POWER SUPPLY CIRCUIT

2-1

2. FRONT CIRCUIT (1/2)

CN902

PIN3
PIN4
PIN9

: -32.4 VKK
: -27.5 FL: -23.7 FL+
: +5.0

2-2

CN902

3. FRONT CIRCUIT (2/2)

2-3

BLOCK DIAGRAM

2-4

2-5

SCHEMATIC DIAGRAMS
1. POWER SCHEMATIC DIAGRAM
NOTES)
NOTES)
NOTES)
NOTES)

2-6

2-7

Warning
Parts that are shaded are critical
With respect to risk of fire or
electricial shock.

2. POWER(SUB) SCHEMATIC DIAGRAM

2-8

2-9

3. MICOM SCHEMATIC DIAGRAM

2-10

2-11

4. FRONT SCHEMATIC DIAGRAM

2-12

2-13

5. DSP&AMP SCHEMATIC DIAGRAM

2-14

2-15

6. I/O SCHEMATIC DIAGRAM

2-16

2-17

7. MAIN MIC SCHEMATIC DIAGRAM

2-18

2-19

WIRING DIAGRAM

(P/No:6850R-GV38Z)

(P/No:6850R-GT29Z)

(P/No:6631R-E071A)

NOTES)
NOTES)
NOTES)
NOTES)

Warning
Parts that are shaded are critical
With respect to risk of fire or
electricial shock.
2-20

2-21

PRINTED CIRCUIT BOARD DIAGRAMS

1. MAIN/DVD P.C. BOARD DIAGRAM (TOP)

2-22

2-23

2. MAIN/DVD P.C. BOARD DIAGRAM (BOTTOM)

2-24

2-25

3. FRONT P.C. BOARD

2-26

2-27

4. SMPS P.C. BOARD

5. JACK P.C. BOARD (OPTIONAL PART)

LOCATION GUIDE

NOTES)
NOTES)
NOTES)
NOTES)

Warning
Parts that are shaded are critical
With respect to risk of fire or
electricial shock.

2-28

2-29

SECTION 3. DVD & AMP PART

ELECTRICAL TROUBLESHOOTING GUIDE
1. System operation flow
Power On

1. 8082 initializes SERVO, DSP & RISC registers

2. Write RISC code to SDRAM
3. Reset RISC

Show LOGO

Yes

Tray Closed?
No

Tray Close to Closed position

SLED at Inner
Side?

Yes

No
SLED Moves to Inner Position

1. Judge whether have disc and disc type

2. Jump to related disc reading procedure

Recieve
OPEN/ CLOSE
Key?
No
1. Execute Pressed Key & IR Key
2. Systemoperati on Routi ne Loop

1. Stop Playback & Open Tray

2. Display tray open message & LOGO

No

Receive
CLOSE Key?

Yes

3-1

2. Test & debug flow

TEST

Check the
AC Vol tage
Power PCBA (110V
or 220V)

No

Check the POWER PART

Yes

Switch on the Power PCBA

Is the
DC Voltage outputs
OK?(-34V,-9V,36V,5.6V,
5V,8V,9V,2.5V,
3.3V)

No

Check the POWER PART

Yes

Are 3.3V and 5V DC

outputs normal on main
PCBA?

No
Check the regulators or diode(D501).

Yes

Update
FLASH(IC500)
successfully?

No

1. Check 27MHz system clock.

2. Check systemreset circuit.
3. Check FLASH R/Wenable signal PRD,
RWR.
4. Check FLASH Memory related circuit.

Yes
Replace FLASH( IC500)
A

3-2

, 115.

3-3

1.
2.

3-4

ES6698.

ES6698.

ES6698.

3-5

3-6

PWM IC
received correct data
stream?

Check connection between

IC300 ABCK, ALRCK,
ASDAT

Normal
PWM IC out?(IC300)

Check the related circuit of

PWM.(Check Audio out
Pins52, 54, 55, 59,62, 68

Check Digital Amp circuit

(IC301, IC302)

3-7

3. AUDIO -COM Circuit(DVD & AMP)

POWER ON

Does CD/DVD appear

at FLD?

NO

Does AV1, TV Audio, AV1 opt. YES

and FM 87.5 appear at FLD

YES
Does Loading appear
at FLD?

NO
NO

NO

YES

NO
Refer to SMPS.

NO
Check oscillator of X101.

YES

Refer to oscillator Circuit.

YES
NO

YES

Check power part of Main

B/D.
YES

Check if DVD an Audio

Micom Insert is OK.

Check Power.

NO

YES

YES
Does no Disc or Time
appear at FLD?

Does it appear DVD Error

at FLD?

Check if IC101 Pin80

is high.

NO

Check IC101 Reset

Waveform.

YES

Check DVD Module.

Check SMPS.

Check if IC101 Pin32, 51, NO

80 are high(5V).

Check 3.3V line.

YES
Check if IC101 Pin96
is high.

NO

YES

Replace IC101.

3-8

Check Power section

Circuit.

OK

DETAILS AND WAVEFORMS ON SYSTEM TEST AND DEBUGGING

1. SYSTEM 27MHz CLOCK,RESET,FLASH R/W SIGNAL
1) ES6698FD main clock is at 27MHz(X501)

3.8V, 27MHz

FIG 1-1

2) ES6698FD reset is high active.

Power Cord in

5.2VA

PWR_CTL(SYSTEM -COM)
IC501 PIN83)
M_RESET(IC501 PIN 207)

URST(IC501 PIN 188)

FIG 1-2

3-9

4) Flash R/W enable signal during download(Downloading)

FRD(IC500 PIN 28)

FWR(IC500 PIN 11)

FIG 1-4

2. SDRAM CLOCK
1) ES6698FD main clock is at 27MHz(X501)
DCLK = 93MHz, Vp-p=2.2, Vmax=2.7V

(IC503 PIN 38)

FIG 2-1

3-10

3. TRAY OPEN/CLOSE SIGNAL

1) Tray open/close waveform

OPEN((PDM03 PIN7)

CLOSE(PDM03 PIN8)
TROPEN(IC402 PIN 4)

TRCLOSE(IC402 PIN 5)

FIG 3-1

2) Tray close waveform

OPEN((PDM03 PIN7)
CLOSE(PDM03 PIN8)

TROPEN(IC402 PIN 4)

TRCLOSE(IC402 PIN 5)

FIG 3-2

3-11

3) Tray open waveform

OPEN(PDM03 PIN7)

CLOSE(PDM03 PIN8)
TROPEN(IC402 PIN 4)

TRCLOSE(IC402 PIN 5)

FIG 3-3

4. SLED CONTROL RELATED SIGNAL (NO DISC CONDITION)

FMSO(2.0V/1.4V/1.0V)
(IC501 PIN 19)
STBY(5V) (IC401 PIN 50)

SL+(4.7V/3.6V/1.9V)
(IC404 PIN 12)

SL-(5.3V/3.7V/2.5V)
(IC404 PIN 11)

FIG 4-1

3-12

5. LENS CONTROL RELATED SIGNAL(NO DISC CONDITION)

FOSO(1.5V/1.4V/1.3V)
(IC501 PIN 12)

F+(4.0V/3.6V/3.2V)
(IC404 PIN 14)

F-(4.0V/3.6V/3.2V)
(IC404 PIN 13)

FIG 5-1

6. LASER POWER CONTROL RELATED SIGNAL(NO DISC CONDITION)

MDI1(0V/180mV)
(IC401 PIN 26)
LD01(5.0V//3.5V)
IC401 PIN 20)

LD02(5.0V/3.6V)
(IC401 PIN 21)

FIG 6-1

3-13

7. DISC TYPE JUDGEMENT WAVEFORMS

F+(IC404 PIN 14)

FE(IC401 PIN 40)

RFL(IC401 PIN 19)

FIG 7-1 (DVD)

F+(IC404 PIN 14)

FE(IC401 PIN 40)

RFL(IC401 PIN 19)

FIG 7-2 (DVD)

3-14

F+(IC404 PIN 14)

FE(IC401 PIN 40)

RFL(IC401 PIN 19)

FIG 7-3 (CD)

F+(IC404 PIN 14)

FE(IC401 PIN 40)

RFL(IC401 PIN 19)

FIG 7-4 (CD)

3-15

8. FOCUS ON WAVEFORMS

FE(IC401 PIN 40)

FOSO(IC501 PIN12)
F+(IC404 PIN 14)

F-(IC404 PIN 13)

FIG 8-1 (DVD)

FE(IC401 PIN 40)

FOSO(IC501 PIN12)
F+(IC404 PIN 14)

F-(IC404 PIN 13)

FIG 8-2 (CD)

3-16

9. SPINDLE CONTROL WAVEFORMS (NO DISC CONDITION)

DMSO(1.4V/1.8V)
(IC501 PIN 18)
SP-(3.6V/2.4V)
(IC404 PIN 18)

SP+(3.6V/4.8V)
(IC404 PIN 17)

FIG 9-1

10. TRACKING CONTROL RELATED SIGNAL(System checking)

TE(IC401 PIN 39)

TRSO(IC501 PIN 13)

T-(IC404 PIN 16)

T+(IC404 PIN 15)

FIG 10-1(DVD)

3-17

TE(IC401 PIN 39)

TRSO(IC501 PIN 13)

T-(IC404 PIN 16)

T+(IC404 PIN 15)

FIG 10-2(CD)

11. RF WAVEFORM

RFOP(2.3V/1.1V)
(IC401 PIN 55)

RFON(0.8V/2.0V)
(IC401 PIN 57)

FIG 11-1

3-18

12. ES6698FD VIDEO OUTPUT WAVEFORMS

1) Full colorbar signal(COMPOSIT)

(IC501 PIN 110)

FIG 12-1

2) Y

(IC501 PIN 113)

FIG 12-2

3-19

13. AUDIO OUTPUT FROM PWM IC

1) Audio L/R

(IC300 PIN 68, 49)

FIG 13-1

2) Audio related Signal

ASDATA3

ASDAT0(IC501 PIN 117)

ABCK(IC501 PIN 123)

ALRCK(IC501 PIN 116)

FIG 13-2

3-20

14. DVD & AMP WAVEFORMS

1)

2)

R315 FRONT L

3)

R310 FRONT R

4)

R316 REAR

5)

R324 REAR

6)

R303 CENTER

R317 WOOFER

3-21

DVD PART SCHEMATIC DIAGRAMS

1. DVD MPEG & DSP SCHEMATIC DIAGRAM

3-22

3-23

2. RF & SERVO SCHEMATIC DIAGRAM

3-24

3-25

3. FRONT MIC SCHEMATIC DIAGRAM

3-26

3-27

SECTION 4. EXPLODED VIEWS

CABINET AND MAIN FRAME SECTION
463

OPTIONAL PART
NOTES) THE EXCLAMATION POINT WITHIN AN

463

EQUILATERAL TRIANGLE IS INTENDED

TO ALERT THE SERVICE PERSONNEL
TO THE PRESENCE OF IMPORTANT
SAFETY INFORMATION IN SERVICE
LITERATURE.

463
250

283

JACK OPTION

452

A26

463

463

274
452
463

A41

274

A43

463

A50

A46

279
A47

452

300

261

261

320

261

4-1

A44

4-2

 DECK MECHANISM EXPLODED VIEW

A26
439

001
002
003

018

A01

014

A02

013
020
017

012

435
015B

015
015A

019
016

440

432
012

012A

030

026

010
024
025

431

036

435

012A

A03

021
430

035A

035
439

4-3

4-4

SECTION 5. SPEAKER SECTION

MODEL : LHS-25SCS
A800

851

853
852

ACCE1
ACCE2
ACCE3
ACCE4
ACCE5

850

5-1

 MODEL : LHS-25SCW
A900

953
954
955

956
952

951
958

957
950

5-2