LG LPC-M140A User manual

MODEL: LPC-M140A/X
SERVICE MANUAL
P/NO : 3829RGT008F OCTOBER, 2007
PORTABLE CD
CASSETTE RECORDER
SERVICE MANUAL
MODEL: LPC-M140A/X
Website http://biz.lgservice.com
Internal Use Only
This S/M developed for the SVC of the unit which is indicated with
the “SVC Model No. : LPC-M140N” in the Main Label.
NOTICE

- 1-1 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
[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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
• IC/TR VOLTAGE & PIN DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19
• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27
• PRINTED CIRCUIT BOARD DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29
❍SECTION 3. EXPLODED VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
❍SECTION 4. REPLACEMENT PARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

- 1-2 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
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 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
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 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
❏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 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
❏SPECIFICATIONS
[General]
[CD]
[Tuner]
AM FM
(MW)
[
TAPE
]
Power supply Refer to the back panel of the unit.
Power consumption 10W
Mass kg
External dimensions (W x H x D) 300 x 252 x 171 mm
Output Power 1W X 2 T.H.D 10%
Speakers 8ΩX 2
Battery Operation DC 9V, six "C"(R14) batteries (not supplied)
Frequency response 100 - 18000 Hz
Signal-to-noise ratio 55 dB
T.H.D %
Tuning Range 87.5 -108 MHz 87.5 -108 MHz/65 -108 MHz
Intermediate Frequency 10.7 MHz
Antenna Telescopic antenna
Tuning Range 522-1620KHz or 530-1720KHz
Intermediate Frequency 455 kHz
Antenna Ferrite bar antenna
Recording System 4 Tracks 2 channel stereo
Frequency Response 125 - 8000Hz
Signal to Noise Ratio 35/40dB (REC/PLAY)
Designs and specifications are subject to change without notice for improvement.
LPC-M140A
MODEL
SECTION LPC-M140X
0.5
3.0

- 1-6 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
❏IDENTIFICATIONS OF CONTROLS
1
2
3
4
56
7
5
8
11
12
Up Panel
Front Panel
9
10
UP Panel/Front Panel
1.CD DOOR
2.FUNCTION SWITCH
[CD/FM/AM/TAPE ]
3.VOLUME CONTROL DIAL
4.DISPLAY WINDOW indicator
5.LEFT/RIGHT SPEAKER
6.TAPE DOOR
7.CD FUNCTION buttons
•CD BACKWARD SKIP//SEARCH ( )
button
•+10 BUTTON
•CD FORWARD SKIP//SEARCH ( )
button
•CD REPEAT button
•CD STOP (■)button
•CD PLAY//PAUSE ( ) button
8.TAPE FUNCTION buttons
•TAPE PAUSE (II) button
•TAPE STOP/EJECT( ) button
•FAST FORWARD ( )button
•REWIND ( )button
•TAPE PLAY ( )button
•RECORD (●)button
9.CD DOOR OPEN ( OPEN)button
10.STEREO indicator
11.TUNING DIAL
12.FREQUENCY indicator

- 1-7 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
Rear Panel/Display Window
1
2
3
4
5
6
Rear Panel
Display Window
1. FM ANTENNA
2. RIF/FM MODE SWITCH (ST./MONO)
HEADPHONE SOCKET ( ): 3.5mm
3. AC POWER INPUT SOCKET
4. CD REPEAT PLAY indicator
5. CD PLAY indicator
6. CD PAUSE indicator
7. CD TRACK NUMBER indicator
8. CD SYNCHRONIZED RECORDING indicator
7
8

- 1-8 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only

- 2-1 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
SECTION 2. ELECTRICAL
❏ADJUSTMENTS
1. FM/AM ADJUSTMENT
NO ITEM INPUT POINT OUTPUT POINT SPECIFICATION ADJUSTING POINT ADJUST FOR
1 AM IF L108 IC101 PIN18 455kHz L102 GAIN MAXIMUM
2 AM COVER LOW L108 IC101 PIN18 515kHz L101 Repeat several times
HI L108 IC101 PIN18 1650kHz TC3
3 AM TRACKING
LOW L108 IC101 PIN18 600kHz L108 GAIN MAXIMUM
HI L108 IC101 PIN18 1400kHz TC4
4 FM COVER LOW C101 IC101 PIN18 87.00MHz L104 Repeat several times
HI C101 IC101 PIN18 108.5MHz TC2
5 FM TRACKING LOW C101 IC101 PIN18 90MHz L103 GAIN MAXIMUM
HI C101 IC101 PIN18 106MHz TC1
2. TAPE DECK ADJUSTMENT
NO ITEM OUTPUT POINT SPECIFICATION ADJUSTING POINT ADJUST FOR
1 TAPE SPEED NOR MTT-111N 3000±90Hz NON
2 AZIMUTH ADJUST MTT114 DECK MECHA ADJ. HOLE GAIN MAXIMUM
3 RECORDING BIAS 55kHz±500Hz L203

- 2-2 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
❏TROUBLESHOOTING GUIDE
Start
Power on?
Check disc circuitry Check connector PN400, 402,
403, CN401, PN404
Check laser circuitry
Check Focus circuitry
Check tracking servo circuitry
Tracking servo check
PN702 1, 4pin check
Check power supply circuitry
IC403 1,4pin 7.2V
IC403 2pin 3.3V
PN402 4pin 3.3V
Does initial
read work?
Does it play?
OK
Is audio output
supplied?
• CD PART

- 2-3 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
IF INITIAL READING IS NOT CARRIED OUT (WITH DISC)
A
3V
0V
1.2V
0V
0.8V
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES YES
YES
YES
YES
Does disc motor Rotate?
Is IC400 pin38 voltage transmitted?
Check the change of
SL +, SL - Voltage.
(IC402 pin 17, 18)
Does PN404 pin2 voltage change
when open/close? CN401 connector defective.
IC400 Defective.
IC402 Defective.
PICK-UP defective.
Does laser light?
focus coil drive wareform.
TRACKING ERROR wareform.
Is rotation normal?
IC401 defective.
PICK-UP defective.
Is HF signal normal without dropout?
Is FA+ waveform output at
IC402 pin3?
Is TE waveform output at
IC401 pin11?
Is HF waveform output?
IC401 pin22
NO

- 2-4 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
NO
NO
NO
NO
NO
NO
When laser does not light
Is IC401 pin7 voltage about 2.5V?
Has laser power source
returned to the Q400?
Flow laser current?
Both voltage of R400 is about 1.0?
Are data transferrd form
IC140?
Does voltage appear at
IC402 17, 18?
MCU IC defective.
MICOM defective.
Connector defective .
IC400, 402 Defective.
Slide motor defective.
Connector defective.
LMT SW defective.
Connector defective.
Q400 defective.
laser defective
Defective laser and/or
connector.
Has pick-up returned to the
innermost position?
Does pick-up stop after
naving moved to the
innermost position?
Are input/output detected
at CN401 pin5?
R400 »1.0V
R400 «1.0V
YES
YES
YES
YES
OPEN CLOSE
YES
YES
YES
YES
YES
YES
(Q400 collector voltage about 1.7V)

- 2-5 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
B
NO
NO
NO
NO
NO
YES
YES
YES
YES
Whe laser light
Does lenses move up and down? Is signal output at focus
search ferminal?
Is signal output at PN400
pin13, 16.
Is IC401 pin15 FEO signal output?
Is IC401 pin8 SEL signal output?
IC401 defective.
IC402 defective.
•Autuator short
•Connecter short
•Connecter short
•IC401 defective.
•Laser diode degraded
•Pick-up defective

- 2-6 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
1. Main part
1-1. Audio Out
No power at IC701 pin1, 12
Replace diode
Fuse change
Is B+ applied to pn701? No
No
Ye s
SW 702 check
Ye s
Transformer check
Ye s
Is Q703, 704 normal?
Fuse open?
No
Replace
Q703, 704
No
D901~904
normal?
Tuner Abnormal
Q901, ZD901
check
Does 4.5V come out at
IC101 pin6?
No
SW 702 check
Ye s
Q101, 102
check
IC101
check
Ye s
Does signal come out at
pin13, 14?
No
Is B+ applied to
Q102?
No
1-2. Tuner

- 2-7 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
1-3. Cassette deck
Deck ABNORMAL
CN7, ZD901
check
Is B+ applied to
LEAF?
No
Does output signal come out
from speaker?
Ye s
CN202
check
SW201 check
HEAD connector check
Ye s
Does signal come out at
IC202 pin4, 11?
No
Does B+ come out
at Q901 collection?
No
CN202 check
No
TAPE REC ABNORMAL
HEAD connector check
CN202 pin3, 4
check
Does IC201 pin4, 11 signal
come out?
No
Does B+ light
at leaf switch
No
Ye s
R203, L204,
L203 check
Does departure signal go
into pn201, pin1, 3
No
Does L203 depart?
Ye s
Ye s
Ye s
1-4. Tape recode

- 2-8 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
• LCD CIRCUIT
Is CD function selection proper?
No
Ye s
Dose display LCD then light? Check LCD supply power
in the power circuitry.
Is MICOM reset circuit
normal?
No •Supply circuitry defective
•Check pn403 pin4
No •Supply circuitry defective
•MICOM surrounding
circuit defective
No
•X400 defective
No
•Pattern defective
•LCD light defective
0VVDD
Reset
3.3V
3.3V
0V
Ye s
Is MICOM (IC400) pin41, 42
normal (osc)?
0.125usec
Ye s
MICOM (IC400) pin52, 53, 54,
55 output wareform normal?
Ye s
3.3V

- 2-9 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
❏INTERAL BLOCK DIAGRAM OF ICs
■ TA2175FN (RF AMP)
• BLOCK DIAGRAM

- 2-10 - Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
■ TC94A58FAG/FB(DSP)
• PIN CONNECTOINS

- 2-11 -
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
• BLOCK DIAGRAM