LG NP5550B User manual

SERVICE MANUAL
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS”
IN THIS MANUAL.
Internal Use Only
Website http://biz.lgservice.com
Portable Bluetooth Speaker
MODEL: NP5550B/ NP5550W
P/NO : AFN77272381 SEPTEMBER, 2015
MODEL: NP5550B/ NP5550W

1-1
CONTENTS
SECTION 1 ........ GENERAL
SECTION 2 ........ CABINET & MAIN CHASSIS
SECTION 3 ........ ELECTRICAL
SECTION 4 ........ REPLACEMENT PARTS LIST

1-2
SECTION 1
GENERAL
CONTENTS
ESD PRECAUTIONS......................................................................................................................................... 1-3
HIDDEN KEY MODE ......................................................................................................................................... 1-4
PROGRAM UPDATE GUIDE ............................................................................................................................ 1-5
SPECIFICATIONS ............................................................................................................................................. 1-6

1-3
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
Hidden Key Description
Dual Play Master “Bluetooth” + “Volume Up” key for 2 seconds
Dual Play Slave “Bluetooth” + “Volume Down” key for 2 seconds
Hardware PMC Mode Entry Push long time the "Power" key
TV Mode Entry “Bluetooth” + “Play/ Pause” key for 2 seconds
Scan Enable “Bluetooth” key for 2 seconds
Bluetooth All Disconnect/ Paired List All Clear “Bluetooth” key for 10 seconds
Demo Entry “Bluetooth” + “Power” key for 7 seconds
APD OFF, Vibe Test Volume, FOTA Administrator Mode “Volume Up” + “Power” key for 2 seconds
Forward Skip Pressing the “Play/ Pause” key twice
Back Skip Pressing the “Play/ Pause” key thrice
Hardware Measurement Mode Entry “Bluetooth” “Volume Down” “Play/ Pause” 
(“Bluetooth” + “Volume Down” + “Play/ Pause”) key
Factory Reset (All LED Blink) “Power” + “Play/ Pause” key for 2 seconds
HIDDEN KEY MODE

1-5
1) Power on the unit.
2) Hidden mode set up : “Volume Up” + “Power” key for 3 seconds. (you can check beep sound)
3) Connect bluetooth and run ‘LG Audio Bluetooth’ App. (you may download on “Google Play store”)
4) FOTA Update : ①Setting menu on the App ②Check version information ③FOTA update
(check FOTA guide in below)
PROGRAM UPDATE GUIDE
Step 1. App setting click
Step 4. Check update new version
Step 2. Check version information
Step 3. FOTA update
Step 5. Start downloading firmware
Y
YG ZG

1-6
SPECIFICATIONS
Power Supply 5 V 1.8 A (AC Adapter)
Built-in rechargeable battery
Power consumption 9 W
Dimensions (W x H x D) Approx. 153 mm x 58 mm x 59.5 mm
Net Weight Approx. 0.47 kg
Operating Temperature 5 °C to 35 °C
Operating Humidity 5 % to 60 %
External Connector ø 3.5 mm mini jack
Micro USB port for charging battery
Communication Bluetooth
Speaker Type : Built-in
Impedance Rate : 4 Ω
Rated Input Power : 10 W
Max. Input Power : 20 W
Battery Battery capacity : 2100 mAh
Operating time is approx. 15 hours.
It may vary depending on the battery status and operational conditions.
• Design and specifications are subject to change without notice.

2-1
SECTION 2
CABINET & MAIN CHASSIS
CONTENTS
DISASSEMBLY INSTRUCTIONS ..................................................................................................................... 2-2
1. HOW TO DISASSEMBLE THE GRILLE................................................................................................... 2-2
ASSEMBLY INSTRUCTIONS ........................................................................................................................... 2-4
1. HOW TO ASSEMBLE THE GRILLE......................................................................................................... 2-4
EXPLODED VIEWS ........................................................................................................................................... 2-7
1. CABINET AND MAIN FRAME SECTION ................................................................................................. 2-7
2. PACKING ACCESSORY SECTION ......................................................................................................... 2-9

2-2
DISASSEMBLY INSTRUCTIONS
Figure 1
Figure 2
1) Set is placed on top of soft sheet so as not to damage.
1. HOW TO DISASSEMBLE THE GRILLE
2) After remove foot on the bottom, remove screw of the rear of Bottom screw using a phillips screwdriver.

2-3
Figure 3
Figure 4
3) Using a thin flat tool (ex. A flathead screwdriver), push the grille to outside.
4) Disassemble grille after holding grille.


2-4
ASSEMBLY INSTRUCTIONS
Figure 1
Figure 2
1) Assemble the hook of set to meet with hook of grille.
1. HOW TO ASSEMBLE THE GRILLE
2) After the hook of set to meet with hook of grille, assemble in the direction of the arrow.

2-5
Figure 3
4) Assemble the rear screw 2 EA using a phillips screwdriver.

2-6

265
251
252
465
A44
465
253
A40
254
255
256 457
465
CABLE1
CABLE3
CABLE2
457
465
260
A45
281
283
284
457 250
282
285
270
271
A48
457
273
274
457
275
A42
262
A49
263
264 266
266
A46
265
457 265
260A
261
261A
BATCNT
BATTERY
EXPLODED VIEWS
1. CABINET AND MAIN FRAME SECTION
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.

Packing
802 Box
Owner’s manual box
802B
803A
803 Packing
Accessory box
802A
801 Owner’s manual 820 USB Data cable
2. PACKING ACCESSORY SECTION

3-1
SECTION 3
ELECTRICAL
CONTENTS
ONE POINT REPAIR GUIDE ............................................................................................................................ 3-2
1. NO POWER PROBLEM ......................................................................................................................... 3-2
2. NO SOUND IN PORTABLE MODE........................................................................................................ 3-3
3. NO SOUND IN BLUETOOTH MODE ..................................................................................................... 3-4
4. NO CHARGING BATTERY..................................................................................................................... 3-5
ELECTRICAL TROUBLESHOOTING GUIDE................................................................................................... 3-6
1. POWER DSP/ AMP ................................................................................................................................ 3-6
2. AMP (PORTABLE MODE)...................................................................................................................... 3-7
3. KEY/ LED ................................................................................................................................................ 3-8
4. CHARGING BATTERY ........................................................................................................................... 3-9
WAVEFORMS OF MAJOR CHECK POINT.................................................................................................... 3-10
WIRING DIAGRAM.......................................................................................................................................... 3-11
BLOCK DIAGRAMS ........................................................................................................................................ 3-13
1. SYSTEM BLOCK DIAGRAM ................................................................................................................ 3-13
2. POWER BLOCK DIAGRAM ................................................................................................................. 3-15
CIRCUIT DIAGRAMS ...................................................................................................................................... 3-17
1. MAIN - AMP CIRCUIT DIAGRAM......................................................................................................... 3-17
2. MAIN - POWER/ CHARGER CIRCUIT DIAGRAM............................................................................... 3-19
3. KEY/ LED CIRCUIT DIAGRAM ............................................................................................................ 3-21
4. I/O JACK CIRCUIT DIAGRAM.............................................................................................................. 3-23
5. BATTERY JUCNTION CIRCUIT DIAGRAM......................................................................................... 3-25
CIRCUIT VOLTAGE CHART........................................................................................................................... 3-27
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-29
1. MAIN P. C. BOARD .............................................................................................................................. 3-29
2. KEY/ LED P. C. BOARD....................................................................................................................... 3-31
3. I/O JACK P. C. BOARD ........................................................................................................................ 3-31
4. BATTERY JUCNTION P. C. BOARD ................................................................................................... 3-31

3-2
ONE POINT REPAIR GUIDE
1-3. Service hint (Any picture/ Remark)
1. NO POWER PROBLEM
No power problem occurs when you power on the unit.
1-1. Solution
Check and replace IC903 on main board.
1-2. How to troubleshoot (Countermeasure)
1) Check battery is enough or not.
2) Check 3V3 (FB901).
 FB901 is not 3.3 V, replace IC903.
< Main board bottom view >
IC903
IC903
FB901
FB901

3-3
ONE POINT REPAIR GUIDE
2-3. Service hint (Any picture/ Remark)
2. NO SOUND IN PORTABLE MODE
No sound problem occurs in portable mode.
2-1. Solution
Check and replace IC500 on main board.
2-2. How to troubleshoot (Countermeasure)
1) Check solder of JK300.
2) Check if signal enters pin2 and pin7 of IC500.
3) Check if signal comes out from pin63 ~ 66 of IC500.
 If it doesn’t work, replace IC500.
4) Check if signal comes out from CN700 L+, L-, R-, R+.
 If it doesn’t work, replace IC700.
< Main board top view > < I/O jack board top view >
< Main board bottom view >
IC500
IC500
JK300
JK300
CN700
CN700
IC700
IC700

3-4
ONE POINT REPAIR GUIDE
3-3. Service hint (Any picture/ Remark)
3. NO SOUND IN BLUETOOTH MODE
No power problem occurs when you power on the unit.
3-1. Solution
Check and replace IC500 on main board.
3-2. How to troubleshoot (Countermeasure)
1) Check if bluetooth is in pairing state with your device.
2) Check if signal comes out from pin63 ~ 66 of IC500.
 If it doesn’t work, replace IC500.
3) Check if signal comes out from CN700 L+, L-, R-, R+.
 If it doesn’t work, replace IC700.
< Main board bottom view >
CN700
CN700
IC700
IC700
< Main board top view >
IC500
IC500

3-5
ONE POINT REPAIR GUIDE
4-3. Service hint (Any picture/ Remark)
< Main board top view >
4. NO CHARGING BATTERY
Battery is not charged.
4-1. Solution
Check and replace IC901 on main board.
4-2. How to troubleshoot (Countermeasure)
1) Check voltage of battery.
2) Check pin3 of IC901. (It should be 4.5 V ~ 5 V)
3) Check pin6 of IC901. (It should be 3.6 V ~ 4.3 V)
 It doesn’t work, replace IC901.
IC901
IC901