LG DP271 User manual

PORTABLE DVD
SERVICE MANUAL
MODEL : DP271/DP271B/LPA-837
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
MODEL: DP271/DP271B/LPA-837
SERVICE MANUAL
P/NO : AFN33673330 APRIL, 2007
http://biz.lgservice.com

CONTENTS
SECTION 1.........SUMMARY
SECTION 2.........EXPLODED VIEWS
SECTION 3.........ELECTRICAL
SECTION 4.........REPLACEMENT PARTS LIST

1-2
SECTION 1
SUMMARY
CONTENTS
PRODUCT SAFETY SERVICING GUIDELINES FOR VIDEO PRODUCTS .............................1-3
SERVICING PRECAUTIONS....................................................................................................................1-4
• GENERAL SERVICING PRECAUTIONS
• INSULATION CHECKING PRODEDURE
• ELECTROSTATICALLY SENSITIVE (ES) DEVICES
SPECIFICATIONS ........................................................................................................................................1-5

1-3
PRODUCT SAFETY SERVICING GUIDELINES FOR VIDEO PRODUCTS
IMPORTANT SAFETY NOTICE
This manual was prepared for use only by properly trained audio-video service
technicians.
When servicing this product, under no circumstances should the original design be
modified or altered without permission from LG Corporation. All components should
be replaced only with types identical to those in the original circuit and their physical
location, wiring and lead dress must conform to original layout upon completion of
repairs.
Special components are also used to prevent x-radiation, shock and fire hazard.
These components are indicated by the letter “x” included in their component
designators and are required to maintain safe performance. No deviations are
allowed without prior approval by LG Corporation.
Circuit diagrams may occasionally differ from the actual circuit used. This way,
implementation of the latest safety and performance improvement changes into the
set is not delayed until the new service literature is printed.
CAUTION : Do not attempt to modify this product in any way. Never perform
customized installations without manufacturer’s approval. Unauthorized
modifications will not only void the warranty, but may lead to property damage or user
injury.
Service work should be performed only after you are thoroughly familiar with these
safety checks and servicing guidelines.
GRAPHIC SYMBOLS
The exclamation point within an equilateral triangle is intended to alert
the service personnel to important safety information in the service
literature.
The lightning flash with arrowhead symbol within an equilateral
triangle is intended to alert the service personnel to the presence of
noninsulated “dangerous voltage” that may be of sufficient magnitude
to constitute a risk of electric shock.
The pictorial representation of a fuse and its rating within an equilateral
triangle is intended to convey to the service personnel the following
fuse replacement caution notice:
CAUTION : FOR CONTINUED PROTECTION AGAINST RISK OF
FIRE, REPLACE ALL FUSES WITH THE SAME TYPE AND
RATING AS MARKED NEAR EACH FUSE.
SERVICE INFORMATION
While servicing, use an isolation transformer for protection from AC line shock. After
the original service problem has been corrected, make a check of the following:
FIRE AND SHOCK HAZARD
1. Be sure that all components are positioned to avoid a possibility of adjacent
component shorts. This is especially important on items trans-ported to and from
the repair shop.
2. Verify that all protective devices such as insulators, barriers, covers, shields, strain
reliefs, power supply cords, and other hardware have been reinstalled per the
original design. Be sure that the safety purpose of the polarized line plug has not
been defeated.
3. Soldering must be inspected to discover possible cold solder joints, solder
splashes, or sharp solder points. Be certain to remove all loose foreign particles.
4. Check for physical evidence of damage or deterioration to parts and components,
for frayed leads or damaged insulation (including the AC cord), and replace if
necessary.
5. No lead or component should touch a high current device or a resistor rated at 1
watt or more. Lead tension around protruding metal surfaces must be avoided.
6. After reassembly of the set, always perform an AC leakage test on all exposed
metallic parts of the cabinet (the channel selector knobs, antenna terminals,
handle and screws) to be sure that set is safe to operate without danger of
electrical shock. DO NOT USE A LINE ISOLATION TRANSFORMER DURING
THIS TEST. Use an AC voltmeter having 5000 ohms per volt or more sensitivity
in the following manner: Connect a 1500 ohm, 10 watt resistor, paralleled by a .15
mfd 150V AC type capacitor between a known good earth ground water pipe,
conduit, etc.) and the exposed metallic parts, one at a time. Measure the AC
voltage across the combination of 1500 ohm resistor and .15 mfd capacitor.
Reverse the AC plug by using a non-polarized adaptor and repeat AC voltage
measurements for each exposed metallic part. Voltage measured must not
exceed 0.75 volts RMS. This corresponds to 0.5 milliamp AC. Any value
exceeding this limit constitutes a potential shock hazard and must be corrected
immediately.
TIPS ON PROPER INSTALLATION
1. Never install any receiver in a closed-in recess, cubbyhole, or closely fitting shelf
space over, or close to, a heat duct, or in the path of heated air flow.
2. Avoid conditions of high humidity such as: outdoor patio installations where dew
is a factor, near steam radiators where steam leakage is a factor, etc.
3. Avoid placement where draperies may obstruct venting. The customer should also
avoid the use of decorative scarves or other coverings that might obstruct
ventilation.
4. Wall- and shelf-mounted installations using a commercial mounting kit must follow
the factory-approved mounting instructions. A product mounted to a shelf or
platform must retain its original feet (or the equivalent thickness in spacers) to
provide adequate air flow across the bottom. Bolts or screws used for fasteners
must not touch any parts or wiring. Perform leakage tests on customized
installations.
5. Caution customers against mounting a product on a sloping shelf or in a tilted
position, unless the receiver is properly secured.
6. A product on a roll-about cart should be stable in its mounting to the cart.
Caution the customer on the hazards of trying to roll a cart with small casters
across thresholds or deep pile carpets.
7. Caution customers against using extension cords. Explain that a forest of
extensions, sprouting from a single outlet, can lead to disastrous consequences to
home and family.

1-4
SERVICING PRECAUTIONS
CAUTION: Before servicing the PORTABLE DVD covered
by this service data and its supplements and addends, read
and follow the SAFETY PRECAUTIONS. NOTE: if
unforeseen circumstances create conflict between the
following servicing precautions and any of the safety
precautions in this publications, always follow the safety
precautions.
Remember Safety First :
General Servicing Precautions
1.Always unplug the PORTABLE DVD AC power cord from
the AC power source before:
(1) Removing or reinstalling any component, circuit board,
module, or any other assembly.
(2) Disconnecting or reconnecting any internal electrical
plug or other electrical connection.
(3) Connecting a test substitute in parallel with an
electrolytic capacitor.
Caution : A wrong part substitution or incorrect polarity
installation of electrolytic capacitors may result in an
explosion hazard.
2.Do not spray chemicals on or near this PORTABLE DVD
or any of its assemblies.
3.Unless specified otherwise in this service data, clean
electrical contacts by applying an appropriate contact
cleaning solution to the contacts with a pipe cleaner,
cotton-tipped swab, or comparable soft applicator.
Unless specified otherwise in this service data, lubrication
of contacts is not required.
4.Do not defeat any plug/socket B+ voltage interlocks with
which instruments covered by this service manual might
be equipped.
5.Do not apply AC power to this PORTABLE DVD and / or
any of its electrical assemblies unless all solid state device
heat sinks are correctly installed.
6.Always connect the test instrument ground lead to an
appropriate ground before connecting the test instrument
positive lead. Always remove the test instrument ground
lead last.
Insulation Checking Procedure
Disconnect the attachment plug from the AC outlet and turn
the power on. Connect an insulation resistance meter (500V)
to the blades of the attachment plug. The insulation
resistance between each blade of the attachment plug and
accessible conductive parts (Note 1) should be more than
1Mohm.
Note 1: Accessible Conductive Parts include Metal panels,
Input terminals, Earphone jacks,etc.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid state) devices can be damaged
easily by static electricity. Such components commonly are
called Electrostatically Sensitive (ES) Devices. Examples of
typical ES 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 ES
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 ES 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 ES devices.
5.Do not use freon-propelled chemicals. These can generate
an electrical charge sufficient to damage ES devices.
6.Do not remove a replacement ES device from its
protective package until immediately before you are ready
to install it. (Most replacement ES devices are packaged
with leads electrically shorted together by conductive
foam, aluminum foil,or comparable conductive material).
7.Immediately before removing the protective material from
the leads of a replacement ES device, touch the protective
material to the chassis or circuit assembly into which the
device will be installed.
Caution: Be sure no power is applied to the chassis or
circuit, and observe all other safety precautions.
8.Minimize bodily motions when handling unpackaged
replacement ES devices. (Normally 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 ES device.)

1-5
SPECIFICATIONS
• DVD PLAYER
Power supply DC 12V (AC adapter terminal), DC 7.4V (Battery)
Power consumption 12W with battery
Weight 190.4g (0.56kg)(without battery pack)
External dimensions(W X D X H) (191 X 74 X 39mm)
Signal system NTSL
Laser Semiconductor laser, wavelength 655nm (DVD),
790nm(CD)
Frequency range (audio) DVD linear sound:48kHZ sampling 4HZ to 20kHZ
96KHZ sampling 4HZ to 44kHZ
Signal-to-noise ratio(audio) More than 85dB
Dynamic range(audio) More than 85dB
Harmonic distortion(audio) 0.08%
Operatingconditions(audio) Temperature: 41°F to 95°F, Operation status: Horizontal
• CONNECTORS
Video input/output(VIDEO IN/OUT) ø2.6x7.8(10/0, 10BC +28/0.10BC) *3F L=1200MM
Audio input/output 2.0Vrms (1 KHZ,0 dB), ø3.5m X 1
(AUDIO IN/OUT, analog audio)
Earphone terminal ø3.5mm stereo mini jack X 1
• LIQUID CRYSTAL DISPLAY
Panel size 7inches (16:9)
Projection system TN color transmission
Driving system TFT active matrix
• SUPPLIED ACCESSORIES
RC Aaudio/Video cable 1
AC Adapter (AD-DP40) 1
Power Cord 1
Battery Pack (DP-BT50) 1
Remote control 1
Battery for Remote control (Lithium) 1

2-1
SECTION 2
EXPLODED VIEWS
CONTENTS
EXPLODED VIEWS .....................................................................................................................................2-2
1. CABINET AND MAIN FRAME SECTION ..................................................................................................2-2
3. PACKING ACCESSORY SECTION...........................................................................................................2-3

2-2
A48
A40 274
293
260
286
275 281
454
455
A00
455
A53
296
295
298
297
451
279
278
284
285
CABLE1
453
262
267
251
252
253
272
277
A51
261
264
277
A46A
A45A
FRONT
BOARD
LCD
BOARD
KEY
BOARD
MAIN BOARD
283
809
A42
A46
CABLE2
CABLE3
453
266
EXPLODED VIEWS
1. CABINET AND MAIN FRAME SECTION

2-3
2. PACKING ACCESSORY SECTION
808 BATTERY
802A BOX INNER
834 CABLE, CIJAR JACK
806 PLUG ASS'Y
833 ADAPTER
900 REMOTE CONTROL
801 OWNER'S MANUAL
804 PACKING SHEET
803 PACKING
802 BOX CARTON

3-1
SECTION 3
ELECTRICAL
CONTENTS
LCD PART ...................................................................................................................................................3-2
LCD ELECTRICAL TROUBLESHOOTING GUIDE .........................................................................3-3
BLOCK DIAGRAM......................................................................................................................................3-5
CIRCUIT DIAGRAM ...................................................................................................................................3-7
PRINTED CIRCUIT DIAGRAM ...............................................................................................................3-9
MAIN PART ...............................................................................................................................................3-11
MAIN ELECTRICAL TROUBLESHOOTING GUIDE .....................................................................3-11
1. POWER (DC-DC CONVERTER) CIRCUIT..........................................................................................3-11
2. MPEG CIRCUIT ...................................................................................................................................3-14
3. RF/SERVO CIRCUIT............................................................................................................................3-15
DETAILS AND WAVEFORMS ON SYSTEM TEST AND DEBUGGING .................................3-19
1. SYSTEM 27MHZ CLOCK, RESET & FLASH R/W SIGNAL................................................................3-19
2. SDRAM CLOCK ...................................................................................................................................3-19
3. DISC TYPE JUDGEMENT WAVEFORM .............................................................................................3-20
4. FOCUS ON WAVEFORM.....................................................................................................................3-22
5. SPINDLE CONTROL WAVEFORM (NO DISC CONDITION)..............................................................3-22
6. TRACKING CONTROL RELATED SIGNAL (SYSTEM CHECKING) ..................................................3-23
7. MT1389 AUDIO OPTICAL AND COAXIAL OUTPUT (ASPDIF) ..........................................................3-24
8. MT1389 VIDEO OUTPUT WAVEFORM ..............................................................................................3-24
9. AUDIO OUTPUT FROM AUDIO DAC..................................................................................................3-25
WIRING CONNECTION DIAGRAMS..................................................................................................3-26
1. WIRING CONNECTION DIAGRAM 1..................................................................................................3-26
2. WIRING CONNECTION DIAGRAM 2..................................................................................................3-27
BLOCK DIAGRAMS.................................................................................................................................3-28
1. OVERALL BLOCK DIAGRAM..............................................................................................................3-28
2. POWER BLOCK DIAGRAM.................................................................................................................3-29
3. SERVO BLOCK DIAGRAM..................................................................................................................3-30
4. SYSTEM BLOCK DIAGRAM................................................................................................................3-31
5. AV BLOCK DIAGRAM ..........................................................................................................................3-32
CIRCUIT DIAGRAMS ..............................................................................................................................3-33
1. MPEG CIRCUIT DIAGRAM .................................................................................................................3-33
2. MEMORY CIRCUIT DIAGRAM ............................................................................................................3-35
3. OPU & MOTOR CIRCUIT DIAGRAM ..................................................................................................3-37
4. AV CIRCUIT DIAGRAM........................................................................................................................3-39
5. CHARGE CIRCUIT DIAGRAM.............................................................................................................3-41
6. FM-TX (OPTION) CIRCUIT DIAGRAM................................................................................................3-43
7. PANEL I/F CIRCUIT DIAGRAM ...........................................................................................................3-45
8. MENU KEY CIRCUIT DIAGRAM .........................................................................................................3-47
9. FRONT KEY CIRCUIT DIAGRAM .......................................................................................................3-49
• CIRCUIT VOLTAGE CHART ..............................................................................................................3-51
PRINTED CIRCUIT DIAGRAMS ..........................................................................................................3-55
1. MAIN P.C.BOARD ................................................................................................................................3-55
2. KEY MENU P.C.BOARD ......................................................................................................................3-59
3. KEY FRONT P.C.BOARD.....................................................................................................................3-59

3-2
LCD PART
1) Power measuring
Measure each power after power supply.
C902(-) : -10V, C901(+) : +15V, C916(+) : +7.5V, C918(+) : +5VD, C914 : 3.3V
2) VCOM waveform adjustment
Adjust the VCOM level while changing the VR901 as below waveform by using the scope in the
C921.
Vcom Waveform
0.17V
3.72V
68.22µs
3.89V
GND

3-3
LCD ELECTRICAL TROUBLESHOOTING GUIDE
Fuse normal? Fuse Replace
YES
YES
NO
Display condition? Inverter abnormal
NO
Appear shadow form
interference in black background
IC(U1) normal operate IC(U1) Check and Replace
YES
NO
+5V normal? IC(U901) Check and Replace
YES
YES
NO
7.5V, 15V, -10V normal? D907, D901, D902
NO
Main B/D on located
RGB signal output? Check and Replace
MPEG1389. (Pin : 184, 185, 187)
YES
NO
IC(U902) and ReplaceVCOM signal? (4.5V) NO

3-4
LCD ELECTRICAL TROUBLESHOOTING GUIDE
LCD MODE CONT signal?
All “LOW” (Normal condition? MAIN B/D Check
YES
NO
TFT LCD pressure voltage?
+15V, -14V, +5V Power source and D901, D902, U901 Check
YES
NO
TFT LCD normal? Replace
YES
NO
Color adjusting normal? Readjust as adjustement standard
YES
Each connector? Replace and Reassemble
YES
NO
ReplaceEND NO

3-5
•STVR •STVL •CKV •UND •OEV •VCOMO •LNR •MOD •OEH •STHL •STHR •CPH3 •CPH2 •CPH1 •89P_R •89P_G •89P_B •SP L- •SP L+ •SP R- •SP R+ •3.3V •BAT_OUT
•PW R CT L _L C D
VCOM BLOCK
•NJM3414A IC •VOLTAGE SUPPLY SMOTHLY
LCD POWER BLOCK
•VG H (15V) •VG L (-1 0V) •7.5V •5V
•MP1540 IC
R/G/B Circuit
BLOCK
•ROUT •GOUT •BOUT
•VCOM
•VGH •VGL •STVR •STVL •CKV •UND •OEV •VC O M O •LNR
•MOD •OE H •STHL •STHR •CPH3 •CPH2 •CPH1 •89P_R •89P_G •89P_B
LCD PANEL
SPEAK
•SP L- •SP L+ •SP R- •SP R+
BACKLIGHT
•BAT_OUT •PWRCTL_LCD
•MP2359 IC
INVERTER POWER BLOCK
Connector
(Main interface)
BLOCK DIAGRAM

3-6
MEMO

TO SERVO
PANEL T-CON I/F
OFF-PAGE CONNECTION
Document Number
07.LCD I/F
LG & MALATA
Monday, January 15, 2007
Document Number
07.LCD I/F
LG & MALATA
Monday, January 15, 2007
Document Number
07.LCD I/F
LG & MALATA
Monday, January 15, 2007
SP_L-
3.3V
SP_L+
SP_R-
SP_R+
GND
STHR
STHL
CPH1
SP_R-
SP_R+
89P_R
89P_G
89P_B
SP_L-
SP_L+
PWRCTL_LCD
OEH
LNR
VCOMO
OEV
CKV
UND
STVR
STVL
STVR
STVL
CKV
OEV
UND
OEH
LNR
STHL
STHR
CPH1
VCOMO
BAT_OUT
PWRCTL_LCD
89P_R
89P_G
89P_B
3.3V
BAT_OUT
3.3V 2,3,4,8
SP_L- 5
SP_L+ 5
SP_R- 5
SP_R+ 5
GND 2,3,4,5,6,8
STVR 2
STVL 2
CKV 2
OEV 2
UND 2
LNR 2
STHL 2
STHR 2
CPH1 2
VCOMO 2
BAT_OUT 4,6
PWRCTL_LCD 2
89P_R 2
89P_G 2
89P_B 2
OEH 2
TP702TP702
TP704TP704
TP701TP701
J701
CON20
J701
CON20
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
TP703TP703
J702
CON18
J702
CON18
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
3-7 3-8
CIRCUIT DIAGRAM

3-9 3-10
PRINTED CIRCUIT DIAGRAM
(TOP VIEW)
(BOTTOM VIEW)
MEMO

3-11
MAIN PART
MAIN ELECTRICAL TROUBLESHOOTING GUIDE
No power on
by ADAPTOR
A
Replace ADAPTOR
NO
YES
1. POWER (DC-DC CONVERTER) CIRCUIT
Is ADAPTOR
out 9.5V
Replace D606
NO
NO
YES
YES
Is D606 OK.
Replace U202 Replace U401 Replace JK902
No +3.3V No +5V No LCD powerNo +18V
YES
YES
Is U202
3.3V OK?
NO Replace U401
Is U401
3.3V OK?
YES
No power on
by BATTERY
A
Replace BATTERY
NO
YES
Is
BATTERY OK?
YES
A

3-12
Audio out abnormal
Check Audio jack & mode
YES
YES
Check +9V
YES
Check signals from MPEG
YES
Replace IC(U504)
MAIN ELECTRICAL TROUBLESHOOTING GUIDE
Audio in/speaker
abnormal
Replace IC(U502)
Replace
Q501 and Q503
Check Audio jack &
mode S/W
NO
YES
YES
Is Q501
and Q503 OK.
Speakers
NO
YES
YES
Is speakers OK.
Replace
B. AUDIO OUT ABNORMAL
D. AUDIO IN/SPEAKER ABNORMAL
Video in abnormal
Refer to LCD part
Replace
(U501 IC)
Check Video jack
& mode
NO
YES
YES
Is U501 OK.
Check
R203, R202, C202
YES
YES
E. VIDEO IN ABNORMAL
Video out abnormal
Check Video jack & mode
YES
YES
Check Video signals from MPEG
YES
Check IC(U501)
YES
Check LC filter
C. VIDEO OUT ABNORMAL

3-13
OPEN/CLOSE abnormal
Check SW401, SW402 switch
Refer to SERVO part.
YES
YES
Check IC(U201) Pin 130 Check the connectin of MD.
YES
Refer to SERVO part.
YES
NO
MAIN ELECTRICAL TROUBLESHOOTING GUIDE
Picture abnormal
Check the disc.
YES
YES
Refer to SERVO part
YES
Check MPEG_CLK
Signal of MPEG part
YES
Check MPEG (IC U201)
YES
Replace B/D
F. PICTURE ABNORMAL
H. OPEN/CLOSE ABNORMAL
Disc error
Check Disc
YES
YES
Refer to SERVO part
YES YES(If OK)
YES(If OK)
YES(If OK)
(If OK)
Replace B/D
G. DISC ERROR