LG LM-K3960A User manual

3CD CHANGER
KARAOKE SYSTEM
SERVICE MANUAL
MODEL: LM-K3960A, LMS-K3960V
SERVICE MANUAL MODEL: LM-K3960A, LMS-K3960V
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL.

- 1-1 -
[CONTENTS]
❍SECTION 1. GENERAL
• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
• SPECIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
❍SECTION 2. ELECTRICAL SECTION
• ELECTRICAL TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• INTERNAL BLOCK DIAGRAM of ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19
• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-35
• PRINTED CIRCUIT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-37
❍SECTION 3. DVD PART ELECTRICAL
• DVD ELECTRICAL TROUBLESHOOTIHG GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
• DVD SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-15
• DVD PRINTED CIRCUIT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-23
❍SECTION 4. EXPLODED VIEWS
• CABINET AND MAIN FRAME SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
• TAPE DECK MECHANISM (A/R & A/S : RIGHT A/R DECK) . . . . . . . . . . . . . . . . . . . . . . . . . .4-3
• TAPE DECK MECHANISM (A/R & A/S : LEFT A/S DECK) . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
• CD MECHANISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
❍SECTION 5. SPEAKER PART
• SPEAKER PART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1
❍SECTION 6. REPLACEMENT PARTS LIST
• REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1

- 1-2 -
SECTION 1. GENERAL
❏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 materials.
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 malfunction 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, therefore, 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 let
contact fingers or other exposed skin.
Magnet
How to hold the pick-up
Conductive Sheet
Cotton swab
Pressure
Pressure

- 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 components
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 magnet-
ism 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 (1M Ω)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent sta-
tic 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.
CLEARING MALFUNCTION
You can reset your unit to initial status if malfunction occur(button malfunction, display, etc.).
Using a pointed good conductor(such as driver), simply short the RESET jump wire on the inside of
the volume knob for more than 3 seconds.
If you reset your unit, you must reenter all its settings(stations, clock, timer)
NOTE: 1. To operate the RESET jump wire, pull the volume rotary knob and release it.
2. If you wish to operate the RESET jump wire, it is necessary to unplug the power cord.
Resistor
(1 Mohm) Conductive
Sheet
Resistor
(1 Mohm)
Armband
RESET jump wire
VOLUME
VOLUME KNOB
DOWN
UP

- 1-4 -
❏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 “DAN-
GEROUS 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.

- 1-5 -
❏SPECIFICATIONS
General
Power supply Refer to the main label.
Power consumption 70 W (LM-K3960Q/LM-KW3960Q/LM-K3860Q model)
50 W (LM-K3565Q model)
30 W (LM-K3365Q model)
Net Weight 6.5 kg
External dimensions (W x H x D) 272 X 322 X 354 mm
Tuner/Amplifier
FM Tuning Range 87.5 - 108.0 MHz or 65 -74 MHz, 87.5 -108.0 MHz
Intermediate Frequency 10.7 MHz
Signal to Noise Ratio 60/55 dB (Mono/Stereo)
Frequency Response 140 - 10000 Hz
AM Tuning Range 522 - 1620 kHz or 520 - 1720 kHz
Intermediate Frequency 450 kHz
Signal to Noise Ratio 30 dB
Frequency Response 140 - 1800 Hz
Output Power LM-K3960Q/LM-KW3960Q model - 130 W + 130 W (4 , THD 10 %)
LM-K3860Q model - 100 W + 100 W (4Ω, THD 10 %)
LM-K3565Q model - 50 W + 50 W (4Ω, THD 10 %)
LM-K3365Q model - 30 W + 30 W (4Ω, THD 10 %)
T.H.D 0.5 %
Frequency Response 140 - 20000 Hz
Signal-to-noise ratio 75 dB
DVD/VCD/CD player
Frequency response (audio) 40 - 20000 Hz
Signal-to-noise ratio (audio) More than 75 dB (1 kHz)
Signal-to-noise ratio (video) More than 55 dB (1 kHz)
Dynamic range (audio) More than 80 dB
Video output 1.0 V (p-p), 75Ω
S-video output (Y) 1.0 V (p-p), 75Ω
(C) 0.3 V (p-p), 75Ω
Component Video output (Y) 1.0 V (p-p), 75Ω
(Pb)/(Pr) 0.7 V (p-p), 75Ω
Speakers
Speaker Name Front Speaker (L/R)
Type Bass Reflex 2Way 3Speaker (LMS-K3960V/LMS-KW3960V/LMS-K3860V)
Bass Reflex 2Way 2Speaker (LMS-K3565V/LMS-K3365V)
Impedance 4
Frequency Response 55 - 20000 Hz
Sound Pressure Level 86 dB/W (1m)
Rated Input Power 130 W (LMS-K3960V/LMS-KW3960V)
100 W (LMS-K3860V)
50 W (LMS-K3565V)
30 W (LMS-K3365V)
Max. Input Power 260 W (LMS-K3960V/LMS-KW3960V)
200 W (LMS-K3860V)
100 W (LMS-K3565V)
60 W (LMS-K3365V)
Net Dimensions (W x H x D) 214 X 386 X 318 mm (LMS-K3960V/LMS-KW3960V/LMS-K3860V)
229 X 224 X 286 mm (LMS-K3565V/LMS-K3365V)
Net Weight 6.3 kg (LMS-K3960V/LMS-KW3960V/LMS-K3860V)
4.2 kg (LMS-K3565V)
3.8 kg (LMS-K3365V)
Cassette tape player
Tape Speed 3000 ±3 % (MTT-111.
NORMAL-SPEED)
Wow Flutter 0.25 %
(TT -111, JIS-WTD)
F.F/REW. Time 120 sec (C-60)
Frequency Response 250 - 8000 Hz
Signal to Noise Ratio 43 dB
Channel Separation 50 dB (P/B)/45 dB (R/P)
Erase Ratio 55 dB (MTT-5511)
Ω
Ω

- 1-6 -

- 2-1 -
SECTION 2. ELECTRICAL SECTION
❏ELECTRICAL TROUBLESHOOTING GUIDE
P7904 6PIN P-SENS check Refer to SMPS
Troubleshooting
Check if IC101 KIA7042
input is over 5V
Check if IC101 KIA7042
input is over 4.3V
IC101 KIA7042
relevant parts check
relevant parts
replacement
normal
IC101 KIA7042?
IC100 78KO/KF2 1 PIN
Power Check
normal
YES
NO
NO
NO NO
YES
YES
YES
YES
■MICOM PART CHECK I

- 2-2 -
Q102 BASE PIN
0.6V HIGH check
Q102 COLLECTOR
0.6V LOW check
Check if IC101
KIA7042 output
power is over 4.3V
relevant parts check
relevant parts
replacement
normal
relevant parts
replacement
relevant parts check
normal
IC 103 8PIN IC 100 19,20,59
PIN 5V check
X101:32.768KHz
X100:9.8304MHz operation
status check
normal
P7904 5PIN 5.6V check
Refer to SMPS
Troubleshooting
Output 5V operation check
D101 1SR35
relevant parts check
normal
relevant parts
replacement
D101 1SR35 both terminal
power check
Q101 EMITTER 5V check
and COLLECTO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
■MICOM PART CHECK II

- 2-3 -
IC100 78KOKF2 22,24
PIN Check
22 PIN DATA MICOM power 5V check Refer to MICOM
Troubleshooting
relevant parts
replacement
relevant parts check
normal
Refer to SMPS
Troubleshooting
P7302 assembly check
Each PIN power check
normal
relevant parts
replacement
normal
P7904 1,2,3 power check
F1+, F2 both terminal: 3.7V and
above VKK: power is over 26V
P7302 connection status
check and power check
F+,F2- both termainal: 3.7V
or above VKK:26V or above
power check
IC301 PT6324 Power check
50 PIN VKK:-26V 9.52
PIN +5V
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO NO
NO
NO
NO
NO
■IC103 KS4CD21CS CHECK
■FLD DISPLAY CHECK