LG LXSU-250, LXU-250-A Service manual
MICRO COMPONENT
SYSTEM
SERVICE MANUAL
MODEL: LX-U250A, LXS-U250
SERVICE MANUAL MODEL: LX-U250A, LXS-U250
- 1-1 -
[CONTENTS]
❍ SECTION 1. GENERAL
• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
❍ SECTION 2. ELECTRICAL
• TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• WAVEFORMS OF MAKOR CHECK POINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
• INTERNAL BLOCK DIAGRAM of ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29
• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-33
• WIRING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-45
• PRINTED CIRCUIT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-47
❍ SECTION 3. EXPLODED VIEWS
• CABINET AND MAIN FRAME SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
• SINGLE DECK MECHANISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3
• CD MECHANISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5
❍ SECTION 4. SPEAKER SECTION
• MODEL: LXS-U250, LXS-W250 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
❍ SECTION 5. REPLACEMENT PARTS LIST
• REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1
- 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 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
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 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 (1M Ω)
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.
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 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.
- 1-5 -
❏ SPECIFICATIONS
NOTE : Specification are subject to change without notice in the course of product improvement.
- 1-6 -
- 2-1 -
CD PART
❏ TROUBLESHOOTING GUIDE
SECTION 2. ELECTRICAL
TURN ON CD
OPEN CLOSE CHECK
“ READING ”
DISPLAY CHECK
READING OK CHECK
IF PLAY, AUDIO
OUTPUT CHECK
OK
CONNECTOR CHECK (PN806)
CHECK LC78690W (IC801)
CHECK AM5810FP (IC802)
CHECK PICKUP MOVEMENT
CONNECTOR CHECK(PN801,PN802)
CHECK MICOM INTERFACE CIRCUIT( PN805 )
CONNECTOR CHECK ( PN802, PN804, PN806 )
CHECK MICOM INTERFACE CIRCUIT( PN805 )
CHECK POWER SUPPLY CIRCUIT( PN806 )
CONNECTOR CHECK ( PN804, PN806 )
- 2-2 -
OPEN CLOSE NG
CONNECTOR LOCKING CHECK ( PN804 )
CHECK POWER SUPPLY CIRCUIT( PN805, PN806)
PN 806 PIN 4 = 12V, PIN 5 = 6.2V
PN805 PIN 1 = 5V
CHECK VOLTAGE CHANGE OF OPEN CLOSE ,
AND IC802 INPUT VOLTAGE PIN 7, 8, 20 (=6.2V)
(PN805 PIN 2:BTL_MUTE, 14:OPEN 15:CLOSE)
DEFECTIVE MAIN
POEWR SUPPLY
DEFECTIVE MICOM
DEFECTIVE
MECHANISM
- 2-3 -
“ READING ” DISPLAY CHECK
(= ONLY “CD “DISPLAY)
CONNECTOR LOCKING CHECK (PN802,
PN804,PN805,PN806 )
DEFECTIVE CONNECTOR OR
MAIN POWER SUPPLAY
DEFECTIVE IC804
DEFECTIVE MICOM OR
CONNECTOR
DEFECTIVE MICOM OR
CONNECTOR
DEFECTIVE IC801
CHECK VOLTAGE THE PIN 2 OF IC804
IC804 PIN 2 : 3.3V
CHECK RESET SIGNAL OF PN805
PN805 PIN 4 : 3V
CHECK POWER SUPPLY
PORT( PN805 ,PN806)
PN 806 PIN 4 = 12V, PIN 5 = 6.2V
PN805 PIN 12 = 5V
CHECK MICOM INTERFACE
CIRCUIT( PN805 )
PN805 PIN 3,4,5,6,7,8,9 SIGNAL CHECK
(3: WRQ, 4 : RESET 5 : DO, 6: DI, 7 : CL
8: CE, 9: FSEQ)
CHECK THE WAVE FORM #1
- 2-4 -
READING OK CHECK
(= “NO DISC” DISPLAY)
CONNECTOR LOCKING
CHECK(PN801,PN802)
DOES SLED MOVE ?
DOES LENSE MOVE ?
(= UP & DOWN)
CHECK PN802 PIN 3,4( SL+,SL-)
A
B
C
D
E
CHECK PN801 PIN 13,16( FA-, FA+)
CHECK PN801 PIN 10( LD )
CHECK PN802 PIN
5,6( SP+,SP-)
CHECK PN801 PIN 14,15
(TA-, TA+)
DEFECTIVE PICKUP OR
IC802 OR IC801
DEFECTIVE PICKUP OR
IC801
DEFECTIVE PICKUP OR
IC802 OR IC801
DEFECTIVE PICKUP OR
IC802 OR IC801
DEFECTIVE PICKUP OR
IC802OR IC801
DOES LASER LIGHT ?
DOES SPINDLE ROTATE ?
IS READING OK ?
- 2-5 -
READING OK CHECK #A
(= “NO DISC” DISPLAY)
A
DOES SL+ WAVEFORM APPEAR
AT
( IC802 PIN 13 AND PN 802 PIN 3)
WAVEFORM #2
SLED MOTOR WAVE
DOES SLIN WAVEFORM
APPEAR AT
( IC802 PIN 5)
WAVEFORM #2
SLED DRIVE WAVE
CHECK PN802 CONNECTOR LINE
DEFECTIVE IC801
DEFECTIVE IC802
DEFECTIVE PN802
CONNECTOR
DEFECTIVE PICKUP
SLED MOTOR
- 2-6 -
READING OK CHECK #B
(= “NO DISC” DISPLAY)
B
DOES FA+ WAVEFORM APPEAR AT
( IC802 PIN 16 AND PN801 PIN 13)
WAVEFORM #3
FOCUS COIL DRIVE WAVE
DOES FAIN- WAVEFORM
APPEAR AT
( IC802 PIN 25)
WAVEFORM #3
FOCUS DRIVE WAVE
CHECK PN801 CONNECTOR LINE
DEFECTIVE IC801
DEFECTIVE IC802
DEFECTIVE PN801
CONNECTOR
DEFECTIVE PICKUP
FOCUS ACTUATOR
- 2-7 -
READING OK CHECK #C
(= “NO DISC” DISPLAY)
C
IS ?V APPLIED TO PIN10 OF
PN501
LASER SUPPLY VOLTAGE CHECK
CHECK PN801 CONNECTOR LINE
IS 3.3 V APPLIED TO
PIN30,36,39,41,61,68,75
OF IC801
RF IC SUPPLY VOLTAGE
CHECK
IS 2.3 V PIN18 OF IC801
LASER CONTROL
VOLTAGE CHECK
DEFECTIVE IC804
DEFECTIVE IC801
DEFECTIVE Q801 OR
D801
DEFECTIVE PN801
CONNECTOR
DEFECTIVE PICKUP
LASER PART
- 2-8 -
READING OK CHECK #D
(= “NO DISC” DISPLAY)
D
DOES SP+ WAVEFORM APPEAR
AT
( IC802 PIN 11 AND PN802 PIN 5)
WAVEFORM #4
SPINDLE MOTOR DRIVE WAVE
DOES SPIN WAVEFORM
APPEAR AT
( IC802 PIN 6)
WAVEFORM #4
SPINDLE DRIVE WAVE
CHECK PN802 CONNECTOR LINE
DEFECTIVE IC801
DEFECTIVE IC802
DEFECTIVE PICKUP
SPINDLE MOTOR
DEFECTIVE PN802
CONNECTOR
- 2-9 -
READING OK CHECK #E
(= “NO DISC” DISPLAY)
E
DOES TA+ WAVEFORM APPEAR AT
( IC802 PIN 17 AND PN801 PIN 14)
WAVEFORM #5
TRACKING COIL DRIVE WAVE
CHECK PN802 CONNECTOR LINE
DEFECTIVE IC801
DEFECTIVE IC802
DEFECTIVE PN802
CONNECTOR
DEFECTIVE PICKUP OR
IC801
DEFECTIVE PICKUP OR
IC801
DOES ARF SIGNAL APPEAR?
(IC801 PIN 2 )
WAVEFORM #6
DOES FE, TE SIGNAL APPEAR?
(IC801 PORT FE:10, TE:16)
WAVEFORM #6
DOES TAIN- WAVEFORM
APPEAR AT
( IC802 PIN 22)
WAVEFORM #5
TRACKING DRIVE WAVE
- 2-10 -
#1. MICOM INTERFACE WAVEFORM
(PN805 PIN 3, 4, 5, 6) during power on
PIN 6 : DI
PIN 5 : DO
PIN 4 : RESET
PIN 3 : WRQ
#1. MICOM INTERFACE WAVEFORM
(PN805 PIN 3, 4, 5, 6) during normal play
PIN 6 : DI
PIN 5 : DO
PIN 4 : RESET
PIN 3 : WRQ
#1. MICOM INTERFACE WAVEFORM
(PN805 PIN 7, 8, 9) during power on
PIN 9 : FSEQ
PIN 8 : CE
PIN 7 : CL
#1. MICOM INTERFACE WAVEFORM
(PN805 PIN 7, 8, 9) during normal play
PIN 9 : FSEQ
PIN 8 : CE
PIN 7 : CL
❏ WAVEFORMS OF MAKOR CHECK POINT
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