LG LPC-LM440A/X User manual

MP3/CD LOGIC DECK
CASSETTE RECORDER
SERVICE MANUAL
MODEL: LPC-LM440A/X
LPC-LM445A/X
SERVICE MANUAL MODEL: LPC-LM440A/X LPC-LM445A/X

- 1-1 -
[CONTENTS]
❍SECTION 1.GENERAL
• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
• SPECIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
• IDENTIFICATIONS OFCONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
❍SECTION 2.ELECTRICAL SECTION
• ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
• INTERAL BLOCK DIAGRAM OF ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17
• IC/TR VOLTAGE & PIN DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27
• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29
• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-41
• PRINTED CIRCUIT BOARD DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-43
❍SECTION 3. EXPLODED VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
❍SECTION 4. REPLACEMENT PARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

- 1-2 -
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.
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.
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.
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.
Storage in conductive bag Drop impact
NEVER look directly at the laser beam, and don’t let
contact fingers or other exposed skin.
Magnet
How to hold the pick-up
Conductive Sheet
Cotton swab
Pressure
Pressure

- 1-3 -
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 magnet-
ism 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 Ω)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent sta-
tic 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.
Resistor
(1 Mohm) Conductive
Sheet
Resistor
(1 Mohm)
Armband

- 1-4 -
❏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 sur-
face 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 gen-
erate 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 “DAN-
GEROUS 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.

- 1-5 -
❏SPECIFICATIONS
[General]
[CD]
[
TAPE
]
Power supply Refer to the back panel of the unit.
Power consumption 40W
Mass
External dimensions (W x H x D) 456 x 178 x 338 mm
Output Power 5W X 2 , 10W
Speakers 3.2ΩX 3
Battery Operation DC 12V, 8 “D”(R20) batteries (not supplied)
Frequency response 100 - 18000 Hz
Signal-to-noise ratio 65 dB
T.H.D %
Tuning Range 87.5 -108 MHz, 65 -74 MHz or 87.5 -108 MHz
Intermediate Frequency 10.7 MHz
Antenna Telescopic antenna
Tuning Range 522 - 1620 kHz or 520 - 1720kHz
Intermediate Frequency 450 kHz
Antenna Ferrite bar antenna
Recording System 4 Tracks 2 channel stereo
Frequency Response 125 - 8000Hz
Signal to Noise Ratio 40/45dB (REC/PLAY)
Designs and specifications are subject to change without notice.
MODEL
SECTION
[Tuner]
AM FM
(MW)
LPC-LM440A
LPC-LM445A
5.1kg
0.5

- 1-6 -
❏IDENTIFICATIONS OF CONTROLS
Front Front

- 1-7 -
Rear Panel
Remote Control
Bottom Panel

- 1-8 -

- 2-1 -
SECTION 2. ELECTRICAL
❏ADJUSTMENTS
1.TAPE DECK ADJUSTMENT
DECK MODE TEST TAPE TEST POINT ADJUSTMENT ADJUST FOR
PLAY BACK MTT-114 L/R Output L/R Maximum
2.RECORD BIAS ADJUSTMENT
DECK MODE TEST TAPE TEST POINT ADJUSTMENT ADJUST FOR
AUTO-RVS 75KHz±5KHz
AUTO-STOP 65KHz±5KHz
3.TAPE SPEED ADJUSTMENT
DECK MODE TEST TAPE TEST POINT ADJUSTMENT ADJUST FOR
PLAYBACK MTT-111 L/R Output 3kHz±50Hz
Azimuth adjusting screw
SR490
REC MODE MTT-5511
C465 OR C415(DECK
CIRCUIT B- POINT)
L405

- 2-2 -
❏TROUBLESHOOTING GUIDE
• CD PART
TURN ON CD
OPEN CLOSE CHECK
CONNECTOR CHECK (PN813)
“READING”
DISPLAY CHECK
CONNECTOR CHECK
(PN802,PN806)
CHECK MICOM INTERFACE
CIRCUIT (PN805)
READING OK CHECK
CONNECTOR CHECK (PN801)
CHECK PICKUP MOVEMENT
CHECK AM5810FP (IC802)
CHECK LC78690N (IC801)
CONNECTOR CHECK
(PN806 Pin1 & Pin3)
IF PLAY, AUDIO
OUTPUT CHECK
OK
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO

- 2-3 -
OPEN COLOSE NG
“READING ”DISLPAY CHECK (=ONLY “CD ”DISPLAY)
DOOR OPEN/CLOSE
DISLPLAY CHECK OPEN/CLOSE S/W CHECK
DEFECTIVE CONNECTOR OR
MAIN POWER SUPPLY
DEFECTIVE IC804
DEFECTIVE MICOM OR
DSP &14P FFC CABLE
IC801 PIN=18 CHECK
“2.45V”
PICK-UP UNIT OR Q801
DEFECTIVE
MAIN B`D CHECK
Q102 “C ”➞ 4.6V)
Check Q101 “B ”4.5V
CONNECTOR LOCKING
CHECK (PN813)
AD 5V CHECK(PN805 Pin3)
CONNECTOR LOCKING CHECK
(PN801,PN805,PN802,PN806)
CHECK POWER SUPPLY
(MAIN PN251)
PN251 PIN 5=6.2V ,PIN 7=6.2V
CHECK VOLTAGE CD B`D IC804
Pin3=6.2V,Pin 2&4=3.3V
CHECK INTERFACE
WITH MICOM MAIN CN111 Pin
6,7,8,9 ,10,11,12 ,13
LASER ON
CD B`D PN801 Pin 10=1.96V
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES

- 2-4 -
READING OK CHECK (=“NO DISC ”DISPLAY)
CONNECTOR LOCKING
CHECK(PN801)
CHECK PN802 Pin3,4
(SL+,SL-)
CHECK PN801 Pin13,16
(FA-,FA+)
CHECK PN802 Pin5,6
(SP+,SP-)
CHECK PN801 Pin14,15
(TA+,TA-)
CHECK PN801 Pin10(LD)
DEFECTIVE PICKUP OR
IC802 OR IC801
DEFECTIVE PICKUP OR
IC802 OR IC801
DEFECTIVE PICK-UP OR
IC802 OR IC801
DEFECTIVE PICKUP OR
IC802 OR IC801
DEFECTIVE PICKUP OR
IC801 OR Q801
DOES SLED MOVE?
DOSE LENSE MOVE?
(UP&DOWN)
DOSE LASER LIGHT?
DOES SPINDLE ROTATE?
IS READING OK?
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
A
B
C
D
E

- 2-5 -
READING OK CHECK #A(=“NO DISC ”DISPLAY)
DOSE SLIN WAVEFORM
APPEAR AT (IC802 Pin5)
DRIVE WAVE
DEFECTIVE IC801
DEFECTIVE IC802
DEFECTIVE PICK-UP
SLED MOTOR
DEFECTIVE PN802
CONNECTOR
DOSE SL+WAVEFORM
APPEAR AT(IC802 Pin13 )
SLED MOTOR WAVE
CHECK PN802
CONNECTOR LINE
YES
NO
NO
NO
NO
NO
A

- 2-6 -
READING OK CHECK #B(=“NO DISC ”DISPLAY)
DOSE FAIN WAVEFORM
APPEAR AT (IC802 Pin22)
DRIVE WAVE
DEFECTIVE IC801
DEFECTIVE IC802
DEFECTIVE PICK-UP
FOCUS ACTUATOR
DEFECTIVE PN801
CONNECTOR
DOSE FA+WAVEFORM
APPEAR AT(IC802 Pin16 )
FOCUS COIL DRIVE WAVE
CHECK PN801
CONNECTOR LINE
YES
NO
NO
NO
NO
NO
B

- 2-7 -
READING OK CHECK #C(=“NO DISC ”DISPLAY)
Q801 EMITTER VOLTAGE
CHECK .3.1V O.K
LASER CONTROL
VOLTAGE CHECK
IC801 Pin 18.2.45
DEFECTIVE IC801
DEFECTIVE IC801
DEFECTIVE Q801
DEFECTIVE PICK-UP
FOCUS ACTUATOR
DEFECTIVE PN801
CONNECTOR
Q801 VOLTAGE CHECK
.1.96V
CHECK PN801
CONNECTOR LINE
YES
YES
NO
NO
NO
NO
NO
NO
C

- 2-8 -
READING OK CHECK #D(=“NO DISC ”DISPLAY)
DOSE SPIN WAVEFORM
APPEAR AT (IC802 Pin6)
SPINDLE DRIVE WAVE
DEFECTIVE IC801
DEFECTIVE IC802
DEFECTIVE PICK-UP
SPINDLE MOTOOR
DEFECTIVE PN802
CONNECTOR
DOSE SP+WAVEFORM
APPEAR AT(IC802 Pin11)
SPINDLE MOTOR DRIVE WAVE
CHECK PN802
CONNECTOR LINE
YES
NO
NO
NO
NO
NO
D

- 2-9 -
READING OK CHECK #E(=“NO DISC ”DISPLAY)
DOSE TAIN WAVEFORM
APPEAR AT (IC801 Pin23)
TRACKING DRIVE WAVE
DEFECTIVE IC801
DEFECTIVE IC802
DEFECTIVE PICKUP
OR IC801
DEFECTIVE PN801
CONNECTOR
DOSE TA+WAVEFORM
APPEAR AT(IC802 Pin17 )
TRACKING COIL DRIVE WAVE
CHECK PN801
CONNECTOR LINE
DOSE RF SIGNAL APPEAR?
(IC801 PORT2)
WAVEFORM#6
YES
NO
NO
NO
NO
NO
E

- 2-10 -
• MAIN POWER
Main Power input (AC-cord in)
LCD Display ”Hello”Check the Voltage-selector
110V/230V (Duble Voltage only)
Check the DC out
of C202(+) Check the Fuse Replace the Fuse
Replace D201,D202,D203D204
Check theD901,D902,
D903,D904(POWER B`D)
Q251 Emittor Voltage
Check(.9.6V) REPLACE Q251
REPLACE IC271
POWER SENSE
BLOCK CHECK
RESET
BLOCK CHECK
REPLACE D181,
D182,D183
REPLACE X102
REPLACE MICOM IC
(IC101 LC877480)
IC271 Vout Voltage Check(.5.2V)
Q265 Collector Voltage
Check(.5V)
Q173 Collector Voltage
Check(.4.6V)
D181,D182,D183 Cathode
Voltage Check(4.6V)
OSC CHECK(X102:9.8304MHz)
NO
NO
YES
NO
NO
NO
NO
NO
NO
NO
NO

- 2-11 -
• MUTING CIRCUIT(MUTE)
• FUNCTION MODE AUDIO ABNORMAL
Dose “HIGH ”appear at
Q601,Q651,Q256(SUB-W)“B ”
Check the “HIGH ”of the
IC101 Pin 9,47 Check the IC101
Check the pattern
Replace the Q601,Q651,
Q256
Check the signal input of PN251
“R-CH ”“L-CH ”
Check the CD B`D
Check the “LOW ”of Q601,
Q605,Q256 “E ”
MUTE
TAPE FUNCTION
Check the signal input
of IC301 Pin 3,26
Refer to “TAPE Trouble Shooting ”
CD FUNCTION
MUTECheck the signal input of
IC301 Pin 6,23
TUNER FUNCTION
Check the signal input of IC301
Pin 4,25
Refer to “Tuner Pack Trouble
Shooting ”
NO
NO
NO
NO NO
YES
YES
YES
YES
YES
YES
YES
YES