LG LAC-M7600 User manual

CAR CD/MP3/WMA Receiver
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
P/N : AFN30086098 APRIL, 2006
MODELS:LAC-M7600R/LAC-M7600
SERVICE MANUAL MODELS: LAC-M7600R/LAC-M7600R

- 1-1 -
[CONTENTS]
❍SECTION 1.GENERAL
• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
❍SECTION 2. ELECTRICAL
• ELECTRICAL TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• WAVEFORMS OF MAJOR CHECK POINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
• INTERNAL BLOCK DIAGRAM of ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
• PRINTED CIRCUIT DIARGAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-31
❍SECTION 3. EXPLODED VIEWS
• CABINET AND MAIN FRAME SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
• MECHANISM (PICK-UP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
❍SECTION 4. REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1

- 1-2 -
SECTION 1. SUMMARY
❏SERVICING PRECAUTIONS
❶ Always disconnect the power source before:
1) Removing or reinstalling any component, circuit board, module or any other instrument assembly.
2) Disconnecting or reconnecting any instrument electrical plug or other electrical connection.
3) Connecting a test substitute in parallel with an electrolytic capacitor in the instrument.
CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in
an explosion hazard.
❷ Do not defeat any plug/socket B+ voltage interlocks with which instruments covered by
this service manual might be equipped.
❹ Do not apply power to this instrument and or any of its electrical assemblies unless all
solid-state device heat sinks are correctly installed.
❸ Always connect a test instrument’s ground lead to the instrument chassis ground before
connecting the test instrument positive lead. Always remove the test instrument ground
lead last.
1) The service precautions are indicated or printed on the cabinet, chassis or components. When servicing,
follow the printed or indicated service precautions and service materials.
2) The Components used in the unit have a specified conflammability and dielectric strength. When replac-
ing any components, use components which have the same ratings. Components marked in the cir-
cuit diagram are important for safety or for the characteristics of the unit. Always replace with the exact
components.
3) An insulation tube or tape is sometimes used and some components are raised above the printed writing
board for safety. The internal wiring is sometimes clamped to prevent contact with heating components.
Install them as they were.
4) After servicing always check that the removed screws, components and wiring have been installed cor-
rectly and that the portion around the service part has not been damaged. Further check the insulation
between the blades of attachment plug and accessible conductive parts.

- 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 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
“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
MP3/WMA Disc compatibility with this unit is limited as follows:
1. Sampling Frequency/8 - 48kHz (MP3) 22.05 - 48kHz (WMA)
2. Bit rate/within 8 - 320kbps (include VBR) (MP3) 32 - 320kbps (WMA)
3. CD-R/CD-RW file system should be “ISO 9660”
4. If you record MP3/WMA files using software which cannot create a FILE SYSTEM, for example
“Direct-CD” etc., it will not be possible to playback MP3/WMA files. We recommend that you use
“Easy-CD Creator” which creates an ISO9660 file system.
Customers should also note that permission is required in order to download MP3/WMA files and
music from the Internet.
Our company has no right to grant such permission.
Permission should always be sought from the copyright owner.
1. GENERAL
Output Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50W x 4CH (Max.)
Power Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DC 12V
Speaker impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8 Ω
Ground System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Negative
Dimensions (W x H x D) . . . . . . . . . . . . . . . . . . . . . . . . . . 182 x 51 x 173 mm (Without Front Panel)
Net Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 kg
2. CD
Frequency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Hz-20 kHz
S/N Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 dB
Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1%
Channel Separation (1kHz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 dB
3. RADIO
FM
Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87.5-107.9 or 87.5-108 MHz
S/N Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 dB
Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7%
Usable Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 dBµV
AM (MW)
Frequency Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520-1720 or 522-1620 kHz
S/N Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 dB
Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0%
Usable Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 dBµV

- 2-1 -
SECTION 2. ELECTRICAL
❏ELECTRICAL TROUBLESHOOTING GUIDE
1. No Power.
Any Key power on.
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
Is power turnd on?
DISC loading?
Does initial reading occur?
Can disc be played?
Is audio output supplied?
OK
Check audio circuitry.
IC506, IC508, PN502
Check tracking servo circuitry.
Q501, IC506, IC504
Check DISC.
Check focusing circuitry.
Q501, IC506
Check laser circuitry.
Q501, IC506
Check loading supply circuitry.
Q701, Q702, Q703, Q704,
PN503, Q503, IC508
Check power supply circuitry.
Q722, Q727, IC702, Q723, Q805,
Q806, Q720, Q719, IC701

- 2-2 -
2. VFD light abnornal.
YES
YES
YES
YES
YES
YES
NO NO
NO
NO
NO
NO
NO
Any Key power on.
(without DISC)
Do display VFD then light? Check voltage in the power
supply circuitry.
Power supply circuitry defective.
Q601, Q602, IC602, T901
• Reset circuit defective.
IC903 Surrounding circuit
defective.
• IC903 Pin14 defective.
X101, X102, C101,
C102, C103, C104
PN103, PN802, PN901,
CN903 front
PCB pattern defective.
IC102, Pin75, 76, 78
front PCB pattern defective.
VFD901, D908, Surrounding
circuit defective.
Display LCD connector
defective.
Is VFD901 F+ (Pin1, 2)
F- (Pin40, 41) Differential
Voltage 2.1~3.15V Input?
Is u-com IC102 Pin75, 76, 78
output waveform normal?
Is u-com IC102 reset circuit
normal? IC102-74Pin
Is u-com IC102 keyin Pin63, 64
5volt input?
Is u-com IC102 X1, X2 terminal
Pin11, 12, 14, 15 input?
OSC : 19.2MHz
OSC : 32.768kHz

- 2-3 -
3. Initial reading is not carried out.
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES (with disc)
NO NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
Slide motor moves
(With disc)
Spindle motor turns
WAVEFORM #1
Does RF waveform
appear? IC501 Pin49
WAVEFORM #2
Check the Voltage change of
PN502 Pin1 (6.4~6.8V)
Check the Voltage IC506
Pin23 (1.4V~1.8V)
Check the Data transmission
from IC510 (58, 72, 70)
DSP WAVEFORM #5
Check the Data transmission
from Pin21 to MICOM
WAVEFORM #5 (IC510)
Check the TRVP
Voltage
IC506 Pin23
Check the change of
SL +, SL – Voltage
IC504 Pin13,14
Does FA+ waveform appear at
IC506 Pin23?
WAVEFORM #3
Laser light check A ?
focus coil drive wareform.
TRACKING ERROR wareform
Defective contact PN501
Defective PICK-UP
Defective IC504
Defective IC506
Defective IC504
Defective MICOM
Defective IC506
Defective
connector CN503
Does TE waveform appear at
IC506 Pin24?
WAVEFORM #4
Is rotation normal?
Is there no dropout of RF signal?
Defective IC506
Defective PICK-UP

- 2-4 -
When laser does not light.
A
Is “2.4V~3.4V” applied to
pin42 of IC506?
( ➀3.4V ➁2.4V)
Did pickup return to
innermost circular?
Does it stop at inner pick
circular after shift?
Is defect output from LMT
SW applied to 68 of IC510?
Is data transferred
from IC510
Does voltage appear at
IC504 Pin 13, 14?
Defective MICOM (IC510)
Defective IC506.
Defective slide motor and/or
connector. (PN504)
Defective LMT SW and/or
connector. (PN504)
Defective MICOM. (IC510)
Defective IC506
Is power supplied to laser Q501?
(Q501 collector: about 1.8V)
OV
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
OPEN CLOSE

- 2-5 -
When laser light.
B
When SPINDLE motor dose not turn
C
NO
NO
NO
NO
YES
YES
YES
YES
Laser lights
Check the signal FOCUS
SEARCH of IC506 Pin25
WAVEFORM #3
Check the signal of IC504
Pin 15, 16
WAVEFORM #3 Defective IC506
Defective IC506
Degraded laser diode
Defective PICK-UP
Defective IC506
Defective IC504
Defective contact PN501
or Defective PICK-UP
Check the change for
SP +, SP –, Voltage
of IC504 Pin11, 12
WAVEFORM #1
Check the change for
SPDO Voltage
of IC506 Pin21
WAVEFORM #1

- 2-6 -
❏WAVEFORMS OF MAJOR CHECK POINT
#1. SPINDLE DRIVE AND MOTOR WAVEFORM
IC501(21), IC502(12) during TOC reading
#2. RF WAVEFORM
IC506(45), IC506(49) during TOC reading
#4. TRACK DRIVE AND MOTOR WAVEFORM
IC502(24), IC504(17) during TOC reading
#3. FOCUS DRIVE AND MOTOR WAVEFORM
IC506(25), IC504(15)
•When focus search failed or there is no disc on tray •There is disc on tray and focus search success

- 2-7 -
❏INTERNAL BLOCK DIAGRAM of ICs
■ FRONT
1) MICOM PIN Assignment

- 2-8 -
2) Pin Descriptions

- 2-9 -

- 2-10 -
3) Pin Descriptions

- 2-11 -
■ TB2903HQ
1) Block Diagram
RL
RL
RL
11
9
8
7
5
2
3
17
18
19
21
24
23
12
15
14
1 20 6
RL
IN1
IN2
IN3
IN4
13
C1
C1
C1
C1
PRE-GND
10 25 22
OUT1 (+)
PW-GND1
OUT1 ( )
OUT2 (+)
PW-GND2
OUT2 ( )
OUT3 (+)
PW-GND3
OUT3 ( )
OUT4 (+)
PW-GND4
OUT4 ( )
TAB VCC1 VCC2
C3
C4
C2
: PRE-GND
: PW-GND
TBYRIP MUTE
C5
16
C6
4
Off-set
DET
MUTE
PLAY
5 V
R1
A
C-GND

- 2-12 -
■ 78K0/KF2
1) Block Diagram

- 2-13 -
2) Pin Lay Out
AVSS
AVREF
P57
P56
P55
P54
P10/SCK10/TXD0
P11/SI10/RXD0
P12/SO10
P13/TXD6
P14/RXD6
P15/TOH0
P16/TOH1/INTP5
P17/TI50/TO50
P30/INTP1
P53
P52
P51
P50
P31/INTP2
P140/PCL/INTP6
P141/BUZ/BUSYO/INTP7
P142/SCKAO
P143/SIA0
P144/SOAO
P145/STBO
P00/TI000
P01/TI010/T000
P02/SO11
P03/SI11
P04/SCK11
P130
P20/ANI0
P21/ANI1
P22/ANI2
P23/ANI3
P24/ANI4
P25/ANI5
P26/ANI6
P27/ANI7
P60/CSL0
P61/SDA0
P62/EXSCL0
P63
P33/TI51/TO51/INTP4
P64
P65
P66
P67
P77/KR7
P76/KR6
P75/KR5
P74/KR4
P73/KR3
P72/KR2
P71/KR1
P70/KR0
P06/TI011/T001
P05/TI001/SSI11
P32/INTP3
P120/INTPO/EXLVI
P47
P46
P45
P44
P43
P42
P41
P40
RESET
P124/XT2/EXCLKS
P123/XT1
IC/FLMD0
P122/X2/EXCLK
P121/X1
REGC
VSS
EVSS
VDD
EVDD
80pin QFP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
21 22 23 24 25 26 27282930 31 32 33 34 35 36 37 38 39 40
80 79 78 77 76 75 74737271 70 69 68 67 66 65 6463 62 61

- 2-14 -
3) Pin Function

- 2-15 -
■ AM5810
1) Block Diagram
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