LG LM K2930 Diagram
- 1-1 -
CONTENTS
SECTION 1. GENERAL
• SERVICING PRECAUTIONS
....................................................................................................................
1-2
• ESD PRECAUTIONS
.................................................................................................................................
1-4
• SPECIFICATIONS
.....................................................................................................................................
1-5
SECTION 2. AUDIO PART
• ADJUSTMENTS
.........................................................................................................................................
2-1
• TROUBLESHOOTING
...............................................................................................................................
2-3
• BLOCK DIAGRAM
...................................................................................................................................
2-13
• SCHEMATIC DIAGRAMS
........................................................................................................................
2-15
• WIRING DIAGRAM
..................................................................................................................................
2-25
• PRINTED CIRCUIT DIARGAMS
..............................................................................................................
2-27
SECTION 3. DVD KARAOKE PART
• KARAOKE TROUBLESHOOTING
.............................................................................................................
3-1
• REPAIRS REGARDING CD MECHANISM
.............................................................................................
3-16
• SCHEMATIC DIAGRAMS
........................................................................................................................
3-17
• IC VOLTAGE SHEET
................................................................................................................................
3-29
• PRINTED CIRCUIT DIAGRAMS
............................................................................................................... 3-33
SECTION 4. EXPLODED VIEWS
• CABINET AND MAIN FRAME SECTION ................................................................................................... 4-1
• TAPE DECK MECHANISM (A/R & A/S : LEFT A/S DECK)
........................................................................
4-3
• TAPE DECK MECHANISM (A/R & A/S : RIGHT A/R DECK)
.....................................................................
4-5
• CD MECHANISM
........................................................................................................................................
4-7
SECTION 5. SPEAKER
..................................................................................................................
5-1
SECTION 6. REPLACEMENT PARTS LIST
...................................................................................
6-1
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.
- 1-2 -
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
Pressure
Pressure
Cotton swab
Conductive Sheet
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
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 (1MΩ)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent
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.
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.
- 1-3 -
Armband
Conductive
Sheet
Resistor
(1 Mohm)
Resistor
(1 Mohm)
VOLUME KNOB
UP
DOWN
VOLUME
RESET jump wire
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.
- 1-4 -
- 1-5 -
NOTE : Specification are subject to change without notice in the course of product improvement.
SPECIFICATIONS
- 1-6 -
MEMO
- 2-1 -
TAPE DECK ADJUSTMENT
1. AZIMUTH ADJUSTMENT
Figure 1. Azimuth Adjustment Connection Diagram
CH1 CH2
Speaker Out
Playback Mode
Head
Test Tape
MTT-114
L ch
R ch
GND
Dual-trace
synchroscope
Electronic
Voltmeter
L out
R out
Unit
SECTION 2. AUDIO PART
ADJUSTMENTS
This set has been aligned at the factory and normally will not require further adjustment. As a result, it is not
recommended that any attempt is made to modificate any circuit. If any parts are replaced or if anyone tampers
with the adjustment, realignment may be necessary.
IMPORTANT
1. Check Power-source voltage.
2. Set the function switch to band being aligned.
3. Turn volume control to minimum unless otherwise noted.
4. Connect low side of signal source and output indicator to chassis ground unless otherwise specified.
5. Keep the signal input as low as possible to avoid AGC and AC action.
Deck Mode Test Tape Test Point Adjustment Adjust for
A Deck Playback MTT-114 Speaker Out
DECK Screw
Maximum
Azimuth Screw
B Deck Playback MTT-114 Speaker Out Azimuth Screw Maximum
2. MOTOR SPEED ADJUSTMENT
Figure 2. Motor Speed Adjustment Connection Diagram
Head
Playback Mode
Unit
Speaker Out
GND
L out
R out
Record/Playback
head
Test Tape
MTT-111
Frequency Counter
Deck Mode Test Tape Test Point Adjustment Adjust for Remark
Normal Speed MTT-111 Speaker Out VR401 3kHz ± 1% A Deck
HI-Speed MTT-111 Speaker Out more than 5.4kHz HI-Speed Dubbing Mode
- 2-2 -
3. RECORD BIAS ADJUSTMENT
Head
Unit
PN202
GND
Record/Playback
head
Test Tape
MTT-5511
Record/Playback
and Pause Mode
Frequency Counter
Deck Mode Test Tape Test Point Adjustment Adjust for
Rec/Pause MTT-5511
ERASE HEAD
L401
60kHz±5kHz (Auto stop)
WIRE(PN202) 85kHz±5kHz(Auto Reverse)
Figure 3. Record Bias Adjustment Connection Diagram
- 2-3 -
AUDIO PART TROUBLESHOOTING
REC (Q252, Q202 ON / R273, R223 High)
Check signal supplied to IC202 pin 11, 14?
Check the output of IC202 Pin9, 16
Check the IC201 pin6 : 12V and pin 4 : High
Check the power or Refer to “IC203
Troubleshooting”
Check the power
supplying to C236(+)
Check the 0.6V of Q208
“B”
Check the “Low” of
Q208 “C”
Replace the Q207
END
Check the Vcc power of IC202 Pin18
Check the oscillation of L203 pin 2, 3
Replace the DECK
Check the “Low” of Q253,
Q203 “B”
Replace the Q253, Q203
Refer to “IC203
Troubleshooting”
Refer to “Power Circuit
Troubleshooting”
Refer to “IC203
trouleshooting”
Replace the Q208
Replace the L203
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
- 2-4 -
P- SENS PART
Does +5V appear at ZD900
Check the waveform of D907
Replace D907
Check the R902 and replace ZD900
Check the Voltage of IC301 PIN 26
VKK PART
Does DC -33V appear at CN302 PIN 4
Does -33V appear
at ZD901(+)
Check the -33V
(Lower) of C919(-)
Replace the
D908, D909
END
Refer to POWER
CIRCUIT
Replace the Q902
Check the Q902
TURN ON
Check the DC -33V of IC301 PIN 51
YES
YES
NO
Dubbing(“NORMAL or REC “//“HIGH”)
Q252, 202 “OFF”//“ON” : R273, 223
“LOW”//“HIGH
Q253, 203 “ON”//“OFF” Refer to “IC203 Troubleshooting”
Refer to “REC Troubleshooting”
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
- 2-5 -
POWER CIRCUIT
Check the Fuse
Replace the Fuse
Replace D900
Replace Transformer
Check the AC Input of
D901
Replace Transformer
Check the AC Input of D901
Replace Transformer
Check the POWER- CONTROL
"HIGH" of IC301 PIN 76
Check the PATTERN
Replace IC301
Check the AC of D901
Replace Transformer
Check the IC902 or Replace
Check the DC Output of
PN900 PIN 1,5
Check the AC Output of
PN900 PIN 2,3
OK
Check the DC +16V (Higher)
of CN901 PIN 6,7
Check the IC902 or Replace
Check the DC +16V (Higher)
of CN901 PIN 6,7
Check the +12V( DC) of
CN901 PIN 5
Check the +12V( DC) of
CN901 PIN 5
Check the DC +16V (Higher)
of CN901 PIN 6,7
Check the POWER- CONTROL
"HIGH" of CN901 PIN 8
Check the IC903 or Replace
Check the DC output of
IC700 PIN 11(- VCC), 12(+ VCC)
Check the DC +12 Output of
CN901 PIN5
Check the DC+ 6.2V Output of
CN901 PIN3
Check the AC+ 12V Output of
CN901 PIN4
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
- 2-6 -
<< CD/ DVD/ KARAOKE
FUNCTION>> Check the DVD-
CONTROL "HIGH" of CN901 PIN 9
Check the +8V( AC) of CN901 PIN 11
Check the +5V of CN901 PIN 12
Check the +3.3V of CN901 PIN 13
Check the +3.3V of CN901 PIN 14
END
Check the POWER- CONTROL
"HIGH" of IC301 PIN 81
Check the PATTERN
Check the DC +16V (Higher)
of CN901 PIN 6,7
Check the +12V( DC)
of CN901 PIN 5
Check the IC904 or Replace
Check the DC +8V (Higher) of
CN901 PIN 10
Check the IC905 or Replace
Check the DC +8V (Higher) of
CN901 PIN 10
Check the IC909, IC908 or
Replace
Check the DC +8V (Higher) of
CN901 PIN 10
Check the IC906, IC907 or
Replace
Check the PATTERN
Check the AC of D901
Replace Transformer
Check the IC902 or Replace
Check the AC Input of D902,
D903
Check the AC Input of D902,
D903
Replace Transformer
Replace Transformer
Replace Transformer
Check the AC Input of D902,
D903
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
- 2-7 -
MUTING CIRCUIT (MUTE)
Check the "HIGH" of IC301
PIN95 (F- MUTE)
Check the Muting mode and
Replace IC301
Check the "HIGH" of Q791
"E" PORT
Check the PATTERN
Check the PATTERN
Replace Q791
Replace Q700, Q750
Check the Muting mode and
Replace IC301
Check the "HIGH" of Q792
"E" PORT
Replace Q792
Replace Q720/ Q770
Check the "HIGH" of Q791 "C" PORT
Check the SIGNAL of Q700, Q750
"C" PORT
OK
Check the "HIGH" of IC301
PIN91 (R- MUTE)
Check the "HIGH" of Q792 "C" PORT
Check the SIGNAL of Q720, Q770
"C" PORT
OK
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
- 2-8 -
Check the "HIGH" of IC301
PIN92 (C- MUTE)
Check the Muting mode and
Replace IC301
Check the "HIGH" of Q793
"E" PORT
Check the PATTERN
Check the PATTERN
Replace Q793
Replace Q1750
Check the Muting mode and
Replace IC301
Check the "HIGH" of Q741
"E" PORT
Replace Q741
Replace Q740
Check the "HIGH" of Q793 "C" PORT
Check the SIGNAL of Q1750 "C"
PORT
OK
Check the "HIGH" of IC301 PIN96
(WOOFER- MUTE)
Check the "HIGH" of Q741 "C" PORT
Check the SIGNAL of Q740 "C"
PORT
OK
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
- 2-9 -
AUDIO ABNORMAL
FUNCTION MODE AUDIO ABNORMAL
YES
YES
YES
YES
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
- 2-10 -
IC301 U- COM IC TROUBLESHOOTING
IC501(EXPENDER IC) TROUBLESHOOTING
Check the +5V of IC301
PIN17,46,90,72
Check the DC+ 5.6V of
CN300 PIN 29
Check the PATTERN
Refer to P- SENS
Troubleshooting
Check the RESET Circuit
Refer to POWER Circuit
Troubleshooting
Check the 5V Input of IC301 PIN26
(POWER- SENS.)
Check the oscillation of X301
When power supplied to IC301 PIN
11 (LOW => HIGH)
Replace IC301
Check the +5V of IC501 PIN16
Refer to POWER Circuit
Troubleshooting
Check the Data of IC301 PIN 3,4
(CD ➞ TAPE FUNCTION)
Refer to IC301 TROUBLE
SHOOTING
Check the pattern of IC301 &
IC501
Re placeReplace IC501
Check the CLK Data of IC552,203
PIN 2, 3
Check the CONTROLL function
OK
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
NO
- 2-11 -
IC700(AMP IC) TROUBLESHOOTING
PLAY
Check the SIGNAL Input of PIN
1,3,20,24,25
Check the POWER of PIN
11 (-) , 12(+)
Check the SIGNAL Output of PIN
5,6,7,8,13,14,15,16,27,28
OK
Check the VCC of IC202 18Pin
Refer to POWER Circuit
Troubleshooting
Check the Deck Mechanism
Replace the Deck Mechanism
Replace IC202
Check the Muting Circuit
Check the SIGNAL Output of IC202
PIN 5,20
Refer to Muting
Troubleshooting
Refer to POWER Circuit
Troubleshooting
Check the DC of PIN
5,6,7,8,13,14,15,16,27,28
Replace POWER IC
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
- 2-12 -
MEMO
- 3-1 -
❐ KARAOKE TROUBLESHOOTING
• Power (SMPS) Circuit
SECTION 3. DVD KARAOKE PART
A. No Power
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