LG LACM-7600-R, LACM-7600 Service 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

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[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

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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 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.

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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 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 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 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.

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❏ 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

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

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SECTION 2. ELECTRICAL

❏ ELECTRICAL TROUBLESHOOTING GUIDE

1. No Power.

Any Key power on.

YES

Is power turnd on?

DISC loading?

Does initial reading occur?

Can disc be played?

Is audio output supplied?

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

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 (with disc)

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

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When laser does not light.

Is “2.4V~3.4V” applied to

pin42 of IC506?

( ➀ 3.4V ➁ 2.4V)

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)

YES

OPEN CLOSE

- 2-5 -

When laser light.

When SPINDLE motor dose not turn

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

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

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❏ 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

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❏ INTERNAL BLOCK DIAGRAM of ICs

■ FRONT

1) MICOM PIN Assignment

+ 27 hidden pages