LG LPC-M155X User manual

MODEL : LPC-M155X , LPC12W
SERVICE MANUAL
PORTABLE CD CASSETTE
RECORDER
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL.
MODEL : LPC-M155X , LPC12W
Website http://biz.lgservice.com
Internal Use Only
P/NO : AFN62795896 NOVEMBER, 2008

Copyright © 2008LG Electronics.Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
- 1-1 -
[CONTENTS]
❍SECTION 1.GENERAL
• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
• SPECIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
❍ SECTION 2. EXPLODED VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
❍SECTION 3.ELECTRICAL SECTION
• TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
• INTERAL BLOCK DIAGRAM OF ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17
• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19
• PRINTED CIRCUIT BOARD DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-21
❍SECTION 4. REPLACEMENT PARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Copyright © 2008LG Electronics.Inc. All right reserved.
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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

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LGE Internal Use Only
- 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

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❏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.

Copyright © 2008LG Electronics.Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
- 1-5 -
❏SPECIFICATIONS
General
Power supply Refer to the back panel of the unit.
Power consumption Refer to the back panel of the unit.
Net Weight 2.3 kg
External dimensions (W x H x D) 330 x 166 x 148 mm
Output Power (T.H.D 10%) 1 W X 2
Speakers 8 ΩX 2
Battery Operation DC 9V,six “C”(R14) batteries
(not supplied)
Tuner
FM
Tuning Range 65 - 108 MHz, 87.5 - 108.0 MHz
Intermediate Frequency 10.7 MHz
Antenna Telescopic antenna
AM
Tuning Range 522 - 1620 kHz or 520 - 1720 kHz
Intermediate Frequency 455 kHz
Antenna Ferrite bar antenna
CD
Frequency response 100 - 18000 Hz
Signal-to-noise ratio 55 dB
T.H.D 0.5 %
Cassette tape player
Recording System 4 Tracks 2 channel stereo
Frequency Response 125 - 8000 Hz
Signal to Noise Ratio 40 dB

Copyright © 2008LG Electronics.Inc. All right reserved.
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LGE Internal Use Only - 1-6 -

LGE Internal Use OnlyCopyright © 2008LG Electronics.Inc. All right reserved.
Only for training and service purposes
2-1 2-2
SECTION 2. EXPLODED VIEWS
A49
A00
450
450
295
294
293
291
290
292
450
460
453
265
454
454
260
260
264
259
254
255
A40 453
252
251
256
250
257
258
253
278
305
A26
450
288
266
289
286
284
310
310
285
287
281
283
263
282
280
453
299
279
302
303
458
300
453
297
278
CABLE1
298
459
301
450
268
455
275
450
273
274
272
267
267
271
304
450
451
452
452
450 456
457
270
315
450
A46
A47
276
277
450
450
261
260
262
454
453
450 453
DECK
MAIN
POWER
269
296
NOTES) THE EXCLAMATION POINT WITHIN AN
EQUILATERAL TRIANGLE IS INTENDED
TO ALERT THE SERVICE PERSONNEL
TO THE PRESENCE OF IMPORTANT
SAFETY INFORMATION IN SERVICE
LITERATURE.
• CABINET AND MAIN FRAME SECTION

Copyright © 2008LG Electronics.Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only 2-3 2-4

Copyright © 2008LG Electronics.Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
- 2-5 -
• PACKING ACCESSORY SECTION
Packing
Packing
Box
803
802
803
Instruction Ass'y
801
Bag
804
305 Power Cord

Copyright © 2008LG Electronics.Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only - 2-6 -

Copyright © 2008LG Electronics.Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
- 3-1 -
• MAIN PART
1. AUDIO OUT
No power at IC701 pin1, 12
Replace diode
Fuse change
Is B+ applied to pn701?
No
SW 702 check
Ye s
Transformer check
Is Q703, 704 normal?
Fuse open?
Replace
Q703, 704
No
D901~904
normal?
Tuner Abnormal
Does 4.5V come out at
IC101 pin6?
SW 702 check
Q101, 102 check
Does signal come out at
pin13, 14?
Is B+ applied to
Q102?
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
No
No
No
No Q901, ZD901 check
IC101 check
Ye s
Ye s
No
2. TUNER
SECTION 3. ELECTRICAL SECTION
❏TROUBLESHOOTING GUIDE

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Only for training and service purposes
LGE Internal Use Only - 3-2 -
3. CASSETTE DECK
Deck ABNORMAL
CN701, ZD901 check
Is B+ applied to
LEAF?
Does output signal come out
from speaker?
CN202 check
SW201 check
HEAD connector check
Does signal come out at
IC201 pin4, 11?
Does B+ come out
at Q901 collection?
CN202 chec
TAPE REC ABNORMAL
HEAD connector check
CN202 pin3, 4 check
Does IC201 pin4, 11 signal
come out?
Does B+ light at leaf switch
R203, L204, L203 check
Does departure signal go
into pn201, pin1, 3
Does L203 depart?
Ye s
Ye s
Ye s
Ye s
Ye s
No
Ye s
No
No
Ye s
No
Ye s
No
Ye s
No
No k
4. Tape recode

Copyright © 2008LG Electronics.Inc. All right reserved.
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- 3-3 -
• LCD CIRCUIT
Is CD function selection proper?
Dose display LCD then light? Check LCD supply power
in the power circuitry.
Is IC1 reset circuit
normal?
• Supply circuitry defective
•Supply circuitry defective
•IC1 surrounding
circuit defective
•X1 defective
•Pattern defective
•LCD light defective
0VVDD
Reset
3.3V
3.3V
0V
Is IC1 pin27, 28 normal (osc)?
0.125usec
IC1 pin59, 60, 61, 62,
output wareform normal?
3.3V
Ye s
Ye s
No No
Ye s
No
Ye s
No
Ye s
No

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LGE Internal Use Only - 3-4 -
Start
Power on?
Check disc circuitry Check connector
CON1, CON2, CON3
Check laser circuitry
Check Focus circuitry
Check tracking servo circuitry
Tracking servo check
PN702 1, 4pin check
Check power supply circuitry
IC4 1,4pin 7.2V
IC4 2pin 3.3V
IC1 12,16,25,50,64,73,98pin 3.3V
IC1 19,29,37,63,66pin 1.6V
Does initial
read work?
Does it play?
OK
Is audio output
supplied?
Ye s
Ye s
Ye s
Ye s
Ye s
No
Ye s
No No
Ye s
Ye s
No
No
• CD PART

Copyright © 2008LG Electronics.Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
- 3-5 -
IF INITIAL READING IS NOT CARRIED OUT (WITH DISC)
A
2V
2V
1.2V
0V
0.8V
Does disc motor Rotate?
Is IC1 pin1 voltage transmitted?
Check the change of
SL +, SL - Voltage.
(IC2 pin 17, 18)
Does CON1 pin5 voltage change
when Limit S/W ON/OFF. CON1 connector defective.
IC1 Defective.
IC2 Defective.
PICK-UP defective.
Does laser light?
focus coil drive wareform.
TRACKING ERROR wareform.
Is rotation normal? IC1 defective.
PICK-UP defective.
Is HF signal normal without dropout?
Is FA+ waveform output at
IC2 pin3?
Is TE waveform output at
IC1 pin96?
Is HF waveform output?
IC1 pin79
1V
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
No
No No
No
Ye s
Ye s Ye s
No
No
B
No
B
No

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When laser does not light
Is IC1 pin90 voltage about 2.5V?
Has laser power source
returned to the Q5?
Flow laser current?
Both voltage of R33 is
about 1.0?
Are data transferrd form IC1?
Does voltage appear at
IC2 17, 18?
IC1 defective.
IC1 defective.
Connector defective .
IC1, 2 Defective.
Slide motor defective.
Connector defective.
LMT SW defective.
Connector defective.
Q5 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 CON1 pin5?
R33 »1.0V
R33 «1.0V
OPEN CLOSE
(Q5 collector voltage about
1.7V)
Ye s
Ye s
No No
No
Yes
Yes
No
No
Ye s
Ye s
No
Ye s
Ye s
Ye s

Copyright © 2008LG Electronics.Inc. All right reserved.
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- 3-7 -
Whe laser light
Does lenses move up and down? Is signal output at focus
search ferminal?
Is signal output at CON3
pin13, 16(FC+, FC-).
Is IC1 pin95 FEI signal output?
Is IC1 pin94 SBAD signal output?
IC1 defective.
IC2 defective.
•Autuator short
•Connecter short
•Connecter short
•IC1 defective.
•Laser diode degraded
•Pick-up defective
Ye s
Ye s
Ye s
No No
No
No
No
Ye s
Ye s
B

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LGE Internal Use Only - 3-8 -
❏INTERAL BLOCK DIAGRAM OF ICs
■ AT24C32
• BLOCK DIAGRAM
■ KIA278R33P1
• BLOCK DIAGRAM
OVER HEAT
PROTECTION
CONTROL
OUTPUT ON/OFF
ASO
PROTECTION
BANDGAP
REFERENCE
-
+
1
4
2
3
V
o
V
IN
Control
GND

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Only for training and service purposes
LGE Internal Use Only
- 3-9 -
■ MM1669AH
• BLOCK DIAGRAM