LG LF-U850D Service Manual
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LG LF-U850D Service Manual

Lg micro hi-fi system service manual
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MICRO HI-FI SYSTEM
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE "SAFETY PRECAUTIONS" IN THIS MANUAL.
MODEL: LF-U850D, LF-U850A,
LFS-U850

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Summary of Contents for LG LF-U850D

  • Page 1 MICRO HI-FI SYSTEM SERVICE MANUAL CAUTION BEFORE SERVICING THE UNIT, READ THE “SAFETY PRECAUTIONS” IN THIS MANUAL. MODEL: LF-U850D, LF-U850A, LFS-U850...

  • Page 2: Table Of Contents

    [CONTENTS] ❍ SECTION 1.GENERAL • SERVICING PRECAUTIONS ..........1-2 •...

  • Page 3: Servicing Precautions

    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. Storage in conductive bag Drop impact 2.
  • Page 4 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.

  • Page 5: Esd Precautions

    ❏ 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.

  • Page 6: Specification

    ❏ SPECIFICATIONS MODEL LF-U850D/A SECTION Power supply Refer to the back panel of the unit. Power consumption 50 W Mass 3.7 kg Battery Operation 187 X 255 X 257 mm Frequency response 40 - 18000 Hz Signal-to-noise ratio 70 dB...

  • Page 7: Troubleshooting Guide

    SECTION 2. ELECTRICAL SECTION ❏ TROUBLESHOOTING GUIDE P-SENS PART CHECK SMPS ASSY CN943 -> 4PIN 5V OPERATION CHECK REFER TO SMPS TROUBLESHOOTING MAIN PCB PN101 4PIN 5V CHECK PN101 CONTACT STATUS CHECK MAIN PCB PN304 27PIN 5V CHECK MAIN PCB PATTERN disconnection check FRONT CN304 7PIN 5V CHECK FRONT IC302 OPERATION AND INPUT VOLTAGE 4.7V~5.0V CHECK IC302 INPUT VOLTAGE 4.7V OR ABOVE , OUTPUT VOLTAGE...
  • Page 8 U-COM 5V VOLTAGE CHECK SMPS ASSY CN943 -> 3PIN 5V OPERATION CHECK REFER TO SMPS TROUBLESHOOTING MAIN PCB PN101 3PIN 5VCHECK PN101 CONTACT STATUS CHECK MAIN PCB PN304 5PIN 5.6VCHECK MAIN PCB PATTERN DISCONNECTION CHECK FFC WIRE ASSEMBLY STATUS CHECK FRONT CN304 29PIN 5.6V CHECK FRONT PCB PATTERN DISCONNECTION CHECK U-COM 17,46,72,90PIN 4.7V~5V CHECK...
  • Page 9 FUNCTION INPUT UNFELT (IC601 BU4052) CD FUNCTION PN805 ASSEMBLY STATUS CHECK MUTING MODE CHECK IC301 REPLACEMENT IC601 (BU4052)5,14PIN INPUT WAVEFORM CHECK C601 (BU4052)16PINVDD,8PIN VSS POWER CHECK REPLACE APPROPRIATE PARTS NORMAL IC601 (BU4052)3,13PIN OUTPUT WAVEFORM CHECK IC602 (MC4580) 2,6PIN INPUT WAVEFORM CHECK REFER TO SMPS IC602 (MC4580) 4PIN VSS,8PIN VDD POWER CHECK.
  • Page 10 AUX FUNCTION JK601 CONTACT STATUS CHECK MAIN PCB PATTERN DISCONNECTION CHECK IC601 (BU4052)4,11PIN INPUT WAVEFORM CHECK IC601 (BU4052)16PINVDD,8PIN VSS POWER CHECK REPLACE APPROPRIATE PARTS IC601 (BU4052)3,13PIN OUTPUT WAVEFORM NORMAL CHECK IC602 (MC4580) 2,6PIN INPUT WAVEFORM CHECK IC602 (MC4580) 4PIN VSS,8PIN VDD POWER REFER TO SMPS CHECK.
  • Page 11 TUNER FUNCTION TUNER MODULE (TU601) OPERATION CHECK Refer to TUNER Troubleshooting and check power (2PIN12Vcheck) IC601 (BU4052)2,15PIN INPUT WAVEFORM CHECK IC601 (BU4052)16PINVDD,8PIN VSS POWER CHECK REPLACE APPROPRIATE PARTS NORMAL IC601 (BU4052)3,13PIN OUTPUT WAVEFORM CHECK IC602 (MC4580) 2,6PIN INPUT WAVEFORM CHECK IC602 (MC4580) 4PIN VSS,8PIN VDD POWER REFER TO SMPS CHECK.

  • Page 12: Internal Block Diagram Of Ics

    ❏ INTERNAL BLOCK DIAGRAM of ICs • MSGEQ7 BLOCK DIAGRAM 63Hz Peak Bandpass Detector Peak 160Hz Detector Bandpass 400Hz Peak Bandpass Detector Audio Anti-Alias 1kHz Peak Filter Bandpass Detector Output DC Out Multiplexor 2.5kHz Peak Bandpass Detector 6.25kHz Peak Bandpass Detector 16kHz Peak...

  • Page 13: Block Diagram

    • PS9813 BLOCK DIAGRAM MBCK PWM_CH1_P *3 or (MAIN) MLRCK Sample Cross- Dynamic PWM_CH1_M MDIN Input Input Volume Rate emph over Bass PWM_CH2_P Mixer Band Control SBCK Converter asis Filter Boost PWM_CH2_M (SUB) SLRCK PWM_CH3_P SDIN PWM_CH3_M PWM_LOL_P Internal Clocks Modulator PWM_LOL_M Automatic...
  • Page 14 PIN DESCRIPTIONS Name Pin NO. Type Descri pti on Power and Groun d PLL_AVDD Analog PLL analog power supply. 2.5V supply voltage. Power PLL_AVSS Analog PLL analog ground. Ground PLL_DVDD PLL peripheral digital power supply. 2.5V supply voltage. Power PLL_DVSS PLL digital ground.
  • Page 15 Name Pin NO. Type Descri pti on PCM Audi o Input/Outp ut I nterface MCLK Main clock for external ADC. Clock frequency is 256fs. MIC_LRCK PCM Word clock (left-right clock) output of external microphone. Word clock rate is Fs(variable) MIC_BCK PCM bit clock output of external microphone.

  • Page 16: System Block Diagram

    • TAS5142 SYSTEM BLOCK DIAGRAM System Microcontroller TAS5508 BST_A Bootstrap Caps BST_B RESET_AB VALID RESET_CD PWM_A OUT_A -Order L-C Left- Output Output Filter Input Channel H-Bridge 1 for Each H-Bridge 1 OUT_B Output PWM_B Half-Bridge 2-Channel H-Bridge BTL Mode OUT_C PWM_C -Order L-C Output...

  • Page 17: Functional Block Diagram

    FUNCTIONAL BLOCK DIAGRAM Under- voltage Protection Internal Pullup VREG VREG Resistors to VREG Power Reset AGND Protection I/O Logic Temp. Sense RESET_AB Overload RESET_CD Isense OC_ADJ Protection GVDD_D BST_D PVDD_D Gate PWM_D Ctrl. Timing OUT_D Rcv. Drive BTL/PBTL Configuration Pulldown Resistor GND_D GVDD_C BST_C...

  • Page 18: Block Diagram

    ❏ BLOCK DIAGRAM 2-12 2-13...
  • Page 19 ❏ SCHEMATIC DIAGRAMS • MAIN SCHEMATIC DIAGRAM 2-14 2-15...

  • Page 20: Schematic Diagrams

    • FRONT SCHEMATIC DIAGRAM 2-16 2-17...
  • Page 21 • SMPS SCHEMATIC DIAGRAM 2-18 2-19...
  • Page 22 ❏ CD PART • WMA MODULE 2-20 2-21...
  • Page 23 • USB PART 2-22 2-23...
  • Page 24 • WMA + USB BLOCK DIAGRAM 2-24 2-25...

  • Page 25: Wiring Diagram

    ❏ WIRING DIAGRAMS 2-26 2-27...
  • Page 26 ❏ PRINTED CIRCUIT DIAGRAMS • MAIN P.C. BOARD (COMPONENT SIDE) 2-28 2-29...
  • Page 27 • MAIN P.C. BOARD (SOLDER SIDE) 2-30 2-31...
  • Page 28 • SMPS P.C.BOARD 2-32 2-33...
  • Page 29 • FRONT P.C.BOARD 2-34 2-35...
  • Page 30 • CD P.C. BOARD (COMPONENT SIDE) • CD P.C. BOARD (SOLDER SIDE) 3-36 3-37...

  • Page 32: Cabinet And Main Frame Section

    SECTION 3. EXPLODED VIEWS • CABINET AND MAIN FRAME SECTION NOTE) Refer to “SECTION 6 REPLACEMENT PARTS LIST” in order to look for the part number of each part.

  • Page 33: Deck Mechanism Exploded View

    • DECK MECHANISM EXPLODED VIEW LOCA. NO. LG PART NO. DESCRIPTION SPECIFICATION 6721RJ0572A DECK ASSEMBLY,AUDIO HOME LF-U850-HZ-(74.8MM) - SPR 4860RB0003A CLAMP HOME CDM-320 MOLD CLAMP ASSY 4405RCD002A MECHANISM ASSEMBLY MAIN LOADING CDM-310 CDP 6717R-A002A PICK UP ASSEMBLY CMS-D77SG6 SAMSUNG FRONT LOADI...
  • Page 34 SECTION 4. SPEAKER PART ❏ MODEL: LFS-U850 - 4-1 -...
  • Page 35 - 4-2 -...

This manual is also suitable for:

Lf-u850aLfs-u850

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