LG LAC2900N User manual

P/NO : AFN73228921 JUNE, 2009
CAR CD/MP3/WMA
RECEIVER
SERVICE MANUAL
MODEL : LAC2900N
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
Website http://biz.lgservice.com
Internal Use Only
MODEL : LAC2900NSERVICE MANUAL

1-1
CONTENTS
SECTION 1 SUMMARY
SERVICING PRECAUTIONS .............................................................................................................................1-2
ESD PRECAUTIONS..........................................................................................................................................1-3
SPECIFICATIONS ..............................................................................................................................................1-4
FIRMWARE UPGRADE METHOD.....................................................................................................................1-5
HOW TO CONNECT AUDIO SET TO POWER SUPPLY..................................................................................1-6
SECTION 2 ELECTRICAL
ELECTRICAL TROUBLESHOOTING GUIDE & WAVEFORMS.......................................................................2-1
1. SYSTEM CONTROL ERROR CORRECTION FLOW CHART .................................................................2-1
2. SOUND ERROR CORRECTION FLOW CHART......................................................................................2-2
3. DISPLAY ERROR CORRECTION FLOW CHART....................................................................................2-6
4. TUNER ERROR CORRECTION FLOW CHART.......................................................................................2-9
5. CDP ERROR CORRECTION FLOW CHART .........................................................................................2-11
6. AUX ERROR CORRECTION FLOW CHART..........................................................................................2-14
• WAVEFORMS ...........................................................................................................................................2-15
• CIRCUIT VOLTAGE CHART ....................................................................................................................2-17
INTERNAL BLOCK DIAGRAM OF ICs ...........................................................................................................2-18
1. IC301 (HA13173AH) ................................................................................................................................2-20
2. IC402 (μPDD78F1164) ............................................................................................................................2-23
3. IC503 (LC786923W) ................................................................................................................................2-28
4. IC504 (AM5810).......................................................................................................................................2-30
5. IC801 (TB2946HQ) ..................................................................................................................................2-31
6. IC802 (BD3702FV)...................................................................................................................................2-37
7. IC901 (MC5502).......................................................................................................................................2-32
WIRING DIAGRAM...........................................................................................................................................2-35
BLOCK DIAGRAM ...........................................................................................................................................2-37
CIRCUIT DIAGRAMS .......................................................................................................................................2-39
1. MAIN CIRCUIT DIAGRAM.......................................................................................................................2-39
2. FRONT CIRCUIT DIAGRAM ...................................................................................................................2-41
3. CDP CIRCUIT DIAGRAM ........................................................................................................................2-43
PRINTED CIRCUIT BOARD DIAGRAMS ........................................................................................................2-45
1. MAIN P.C.BOARD ...................................................................................................................................2-45
2. FRONT P.C.BOARD ................................................................................................................................2-47
3. CDP P.C.BOARD.....................................................................................................................................2-49
SECTION 3 EXPLODED VIEWS
1. CABINET AND MAIN FRAME SECTION ..................................................................................................3-1
2. MECHANISM(PICK-UP) SECTION ...........................................................................................................3-3
SECTION 4 REPLACEMENT PARTS LIST

1-2
SECTION 1 SUMMARY
SERVICING PRECAUTIONS
1. 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.
2. Do not defeat any plug/socket B+ voltage interlocks with which instruments covered by this service
manual might be equipped.
3. Do not apply power to this instrument and or any of its electrical assemblies unless all solid-state de-
vice heat sinks are correctly installed.
4. 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 replacing
any components, use components which have the same ratings. Components marked in the circuit 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 correctly
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 com-
monly 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 know earth ground. Alternatively, obtain and wear a com-
mercially 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 de-
vices.
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 ARROWHEAD 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 INTENED TO ALERT
THE SERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN
SERVICE LITERATURE.

1-4
SPECIFICATIONS
• GENERAL
Output Power 53 W x 4 CH (Max.)
Power Source DC 12V
Speaker impedance 4Ω
Ground System Negative
Dimensions (W x H x D) 180 x 50 x 176 mm (Without Control Panel)
Net Weight 1.3kg
• TUNER
FM
Frequency Range 87.5 ~ 107.9, 87.5 ~ 108MHz
S/N Ratio 55dB
Distortion 0.7%
Usable Sensitivity 12dBμV
AM (MW)
Frequency Range 520 ~ 1720 or 522 ~ 1620 kHz
S/N Ratio 50dB
Distortion 1.0%
Usable Sensitivity 28dBμV
• CD
Frequency Response 20Hz ~ 20kHz
S/N Ratio 80dB
Distortion 0.12%
Channel Separation (1kHz) 55dB
• AUX
Frequency Response 20Hz ~ 20kHz
S/N Ratio 80dB
Distortion 0.1%
Channel Separation (1kHz) 45dB
Max Input Level (1kHz) 1.1V
Designs and specifications are subject to change without notice.