LG SB74 Manual de usuario
MODEL : SB74
SERVICE MANUAL
Stylish Powerful Portable Boom Box
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
MODEL : SB74
Website http://biz.lgservice.com
Internal Use Only
SEPTEMBER, 2009P/NO : AFN73250927
1-1
SECTION 1. GENERAL
• SERVICING PRECAUTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
•
PROGRAM DOWNLOAD GUIDE
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
SECTION 2. EXPLODED VIEWS
• CABINET AND MAIN FRAME SECTION (SB74) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• PACKING ACCESSORY SECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
SECTION 3. ELECTRICAL PART
• TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
• WAVEFORMS OF MAJOR CHECK POINT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14
• BLOCK DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15
• CIRCUIT DIAGRAMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17
• CIRCUIT VOLTAGE CHART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27
• PRINTED CIRCUIT DIARGAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29
SECTION 4. REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
[CONTENTS]
1-2
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 mate-
rials.
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 malfunc-
tion 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, there-
fore, 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 allow
contact fingers or other exposed skin.
Magnet
How to hold the pick-up
Conductive Sheet
Cotton swab
Pressure
Pressure
SECTION 1. GENERAL
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 compo-
nents 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 magnetism 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 (1 MΩ)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to pre-
vent static 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 MΩ)Conductive
Sheet
Resistor
(1 MΩ)
Armband
1-4
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.
SAFETY PRECAUTIONS
1-5
PROGRAM UPGRADE PROCESS
Important Notice : When ugrade the software running,
Do not shut down the power, it may damage the unit
1. Copy the software file into the USB flash, As the file name is [SB74_VXX.mcs]
2. Insert the USB flash into the USB host
3. Set Function to the USB position.
Appear onto the LCD
CHECKING
UPGRADE
SUCCESS
4. After finish, Un-plug the AC inlet about 2sec. Than connect the AC inlet source again.
5. Software upgrade completed.
6. You can check the software version.
7. At Power on mode, Press STOP button of the set and PLAY key of the RCU together
LCD shows SB74_VXX(version)
1-6
GENERAL
Power supply Refer to main label.
Power consumption Refer to main label.
Net Weight 3.3 kg
External dimensions (W x H x D) 524 x 155 x 288 mm
CD
Laser Semiconductor laser, wave length 780nm
Frequency response (Audio) 100Hz to 18KHz
Single to noise ratio More than 55dB
Dynamic range (Audio) More than 50dB
TUNER(FM)
Tuning range 87.5 ~ 108MHz
Intermediate Frequency 128KHz
Oscillator frequency 32.768KHz
Frequency response (Audio) 100 Hz ~ 10 KHz
AMPLIFIER
PORTABLE IN
Out put Power 7.5 W + 7.5 W
In put sense 500 mV
Frequency response (Audio) 100 Hz ~ 18 KHz
Signal to Noise Ratio More than 55dB
SPEAKER
Model G-C40-55-8F-10W
Type 1 Way 1 Speaker
Impedance 8 Ω
Rfrequency Response 120 Hz ~ 20 KHz
Rated Input Power 8 W
Max. Input Power 10 W
Net Dimension (HxDxd) 42 x 102 x50 mm
Net Weight 240 g
Designs and specifications are subject to change without pior notice.
SPECIFICATIONS
B
C
A
M
F
K
NN
L
E
D
I
L
I
H
M
G
K
C
J
E
J
D
G
H
F
A
B
MCU SMPS
MAIN
251
252
252
254
258
255
263
264
265
263
A47
270
271
272
278
455
273
269 457
268
266
A42
A43
262
261
260
A46
A45
267
256 453
252A
257L 257R
259L
259R
CABLE1
CABLE4
279R
279L
A26
280
300
277A
277B
276
275R
275L
274L
274R
CABLE3
CABLE2
BELT1
277C
458
461
463
456
462
456
462
451
460
460
451
458
458
451
451
451
460
FRONT
USB
• CABINET AND MAIN FRAME SECTION (SB74)
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.
SECTION 2. EXPLODED VIEWS
2-1 2-2
2-3 2-4
2-5
• PACKING ACCESSORY SECTION
Remote Control900
Battery
808
Instruction Ass'y801
Packing803
Box
802
Packing
803
Bag804
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