LG LACM-1500-R Service manual

SERVICE MANUAL MODEL : LAC-M1500R
DETACHABLE FRONT PANEL CAR CD RECEIVER
SERVICE MANUAL
MODEL : LAC-M1500R
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL.
- 1-1 -
SECTION 1. SUMMARY
• 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
.........................................................................................................................
2-17
• SCHEMATIC DIAGRAM
................................................................................................................
2-19
• PRINTED CIRCUIT DIAGRAM
......................................................................................................
2-25
SECTION 3. CABINET MAIN CHASSIS & MECHANISM
• EXPLODED VIEW
...........................................................................................................................
3-1
SECTION 4. REPLACEMENT PARTS LIST
....................................................................
4-1
[CO
- 1-2 -
SERVICING PRECAUTIONS
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.
Do not defeat any plug/socket B+ voltage interlocks with which instruments covered by this service
manual might be equipped.
Do not apply power to this instrument and or any of its electrical assemblies unless all solid-state
device heat sinks are correctly installed.
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.
SECTION 1. SUMMARY
- 1-3 -
ESD PRECAUTIONS
[Electrostatically Sensitive Devices (ESD)]
Some semiconductor (solid state) devices can be damaged easily by static electricity. Such omponents 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 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 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 material).
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 be installed.
CAUTION: Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.
8) Minimize bodily motions when handling 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 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 -
1. GENERAL
Power requirements
.....................................................................................................................
DC12V~15V
Ground system
...................................................................................................................................
Negative
Dimensions(W x H x D)
......................................................................................................
188 x 58 x 166mm
Weight
..............................................................................................................................................
Net: 1.3kg
2. RADIO SECTION
FM AM(MW)
Frequency range 65.0~74.0MHz(Optional), 522~1,620kHz
87.5~108MHz (Optional:530~1,710kHz/ 520~1,620kHz)
Intermediate frequency 10.8MHz 450kHz
Usable sensitivity 10dBµV 28dBµV
Signal to noise ratio 55dB 45dB
3. COMPACT DISC SECTION
Frequency response
.....................................................................................................................
40Hz~20kHz
Channel separation
......................................................................................................................
50dB(1kHz)
Signal to noise ratio ..................................................................................................................................
60dB
4. AUDIO SECTION
Maximum output power
.......................................................................................................................
50W x 4
Speaker impedance
...............................................................................................................
4x 4 or 8x 4
NOTE: The design and specifications are subject to change without notice in the sourse of product
improvement.
SPECIFICATIONS
- 2-1 -
ELECTRICAL TROUBLESHOOTING GUIDE
Any Key power on.
Is power turnd on?
DISC loading?
Does initial reading occur?
Can disc be played?
Is audio output supplied?
Check power supply circuitry.
Q380, Q381, Q382,Q230
IC201 Pin1, IC401 Pin3.
Check loading supply circuitry.
Q350,Q351,Q353,
PN505, IC401 Pin1
Check laser circuitry.
Q501, IC502
Check focusing circuitry.
Q501,IC501.
Check DISC.
Check tracking servo circuitry.
Q501,IC502, IC501.
Check audio circuitry.
IC501,IC601,IC803.
OK
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
(1) No Power.
SECTION 2. ELECTRICAL
- 2-2 -
YES
YES
YES
YES
YES
YES
(2) LCD light abnornal.
Any Key power on.
(without DISC)
Do display LCD then light?
Check voltage in the power supply
circuitry.
Power supply circuitry defective.
Q371,Q372,IC403
• Reset circuit defective. IC201 Surrounding circuit defective.
• IC401 pin89 defective.
X401, X422, C412,
C413, C415, C416.
Q260, PN401 front
PCB pattern defective.
IC401, Pin66, 67, 87
front PCB pattern defective.
IC901, Surrounding circuit
PCB pattern defective.
Is u-com IC401 reset circuit
normal? Pin88
Is u-com IC401 keyin Pin9, 37, 51,
52, 64 5volt input?
Is u-com IC401 Pin 66,67,87
output waveform normal?
Is IC901 Com1, Com2, Com3
output waveform normal?
Display LCD connector defective.
Is u-com IC401X1, X2 terminal
Pin38,39,41,42 input?
OSC : 12.5MHz
OSC : 32.768kHz
NO
NO
NO
NO
NO
NO
NO
- 2-3 -
(3) Initial reading is not carried out.
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES (with disc)
YES
YES
Slide motor moves
(With disc)
Spindle motor turns
WAVEFORM #1
Does RF waveform appear?
IC502 Pin8
WAVEFORM #2
Check the Data transmission from
CN503(18,20,21) to CD DSP
WAVEFORM #5
Check the Data transmission from
CN503 Pin19 to MICOM
WAVEFORM #5
Check the TRVP
Voltage
IC501 Pin31
Check the change of SL
+, SL - Voltage
IC504 Pin13,14
Check the Voltage change of
CN503 Pin10(6.4~6.8V)
Check the Voltage IC501 Pin31
(1.4V~1.8V)
Defective connector
CN503
Defective IC501
Defective connector
CN503
Defective MICOM
Defective connector
CN503
Defective IC504
Defective IC501
Defective IC504
Defective contact CN502
Defective PICK-UP
Laser light check
A ?
focus coil drive wareform.
TRACKING ERROR wareform
Is rotation normal?
Defective IC501
Defective PICK-UP
Is there no dropout of RF signal?
Does FA+ waveform appear at
IC501 Pin31?
WAVEFORM #3
Does TE waveform appear at
IC502 Pin21?
WAVEFORM #4
1.4~1.8V
3~4V
- 2-4 -
NO
NO
NO
NO
NO
NO
When laser does not light.
Is “2.4V~3.4V” applied to pin2 of IC502?
(
3.4V 2.4V)
Is power supplied to laser Q501?
(Q 501 collector: about 1.8V)
Is data transferred from
MICOM IC ?
Does voltage appear at IC504 Pin 13, 14?
Defective MICOM or CN503.
Defective MICOM.
Defective IC502
Defective IC501,IC502
Defective slide motor and/or connector.(CN501)
Defective LMT SW and/or connector. (CN501,CN503)
Did pickup return to
innermost circular?
Does it stop at inner pick circular after shift?
Is defect output from LMT SW applied to Pin 4 of PN505?
YES
YES
YES
YES
OPEN
CLOSE
YES
YES
YES
A
OV
- 2-5 -
When laser light.
B
When SPINDLE motor dose not turn
C
NO
NO
YES
YES
YES
Laser lights
Check the signal of IC504
Pin 15, 16
WAVEFORM #3
Check the signal FOCUS
SEARCH of IC501 Pin 37
WAVEFORM #3
Defective IC501
Defective IC501
Degraded laser diode
Defective PICK-UP
YES
NO
NO
YES
Check the change for
SPDO Voltage of
IC501 Pin29
WAVEFORM #1
Check the change for SP +, SP
-, Voltage of IC504 Pin11, 12 WAVEFORM #1
Defective IC501
Defective IC504
Defective contact CN502 or
Defective PICK-UP
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