LG FFH-3765MVA Service Manual
  1. Manuals
  2. Brands
  3. LG Manuals
  4. Stereo System
  5. FFH-3765MVA
  6. Service manual
LG FFH-3765MVA Service Manual

LG FFH-3765MVA Service Manual

Hide thumbs
Table of Contents

Advertisement

Quick Links

• SERVICING PRECAUTIONS ..................................................................................................................... 1-2
• ESD PRECAUTIONS .................................................................................................................................. 1-4
• SPECIFICATIONS ...................................................................................................................................... 1-5
• ADJUSTMENTS .......................................................................................................................................... 2-1
• TROUBLESHOOTING ................................................................................................................................ 2-3
• WAVEFORMS OF MAJOR CHECK POINT ............................................................................................. 2-20
• BLOCK DIAGRAM .................................................................................................................................... 2-21
• SCHEMATIC DIAGRAMS ......................................................................................................................... 2-23
• PRINTED CIRCUIT DIARGAMS ............................................................................................................... 2-33
• INTERNAL BLOCK DIAGRAM OF IC's .................................................................................................... 2-43
• REPAIRS REGARDING CD MECHANISM .............................................................................................. 2-55
• CABINET AND MAIN FRAME SECTION ................................................................................................... 3-1
• TAPE DECK MECHANISM: AUTO STOP DECK(OPTIONAL) ................................................................... 3-3
• TAPE DECK MECHANISM: AUTO REVERSE DECK ................................................................................. 3-5
• CD MECHANISM ......................................................................................................................................... 3-7
SECTION 5. REPLACEMENT PARTS LIST
CONTENTS
..............................................................................................................................
...........................................................................................
- 1-1 -
4-1
5-1

Advertisement

Table of Contents
loading

Related Manuals for LG FFH-3765MVA

Summary of Contents for LG FFH-3765MVA

  • Page 1: Table Of Contents

    CONTENTS SECTION 1. GENERAL • SERVICING PRECAUTIONS ........................1-2 • ESD PRECAUTIONS ..........................1-4 • SPECIFICATIONS ............................1-5 SECTION 2. ELECTRICAL • ADJUSTMENTS ............................2-1 • TROUBLESHOOTING ..........................2-3 • WAVEFORMS OF MAJOR CHECK POINT ..................... 2-20 • BLOCK DIAGRAM ............................ 2-21 •...

  • Page 2: Section 1. General

    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 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.

  • Page 4: 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 5: Specifications

    SPECIFICATIONS 1. AMP SECTION 1) Power Output (6 Ω, 2 channel, T.H.D. 10%) ................50W+50W 2) T.H.D .............................. 0.2% 3) Frequency Response (-3dB down) ..................42Hz~25kHz 4) Signal-to-noise Ratio ........................80dB 5) Input Sensitivity AUX ......................400±50mV 6) Channel Difference 1kHz ......................... 3dB 2.
  • Page 6 3. TAPE DECK SECTION 1) Tape Speed (MTT-111) / Normal Speed ................3(±1.5%)kHz 2) Wow Flutter (MTT-111) ......................... 0.25% 3) Fast Forward and Rewind Time (C-60) ..................120sec 4) Frequency Response (6dB range) ..................125Hz~8kHz 5) Signal-to-noise Ratio (Playback/Record) ................43dB/43dB 6) Distortion (Playback/Record) ......................

  • Page 7: Section 2. Electrical

    SECTION 2. ELECTRICAL 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.
  • Page 8 3. RECORD BIAS ADJUSTMENT Deck Mode Test Tape Test Point Adjustment Adjust for ERASE HEAD 60kHz±5kHz (Auto stop) Rec/Pause MTT-5511 L203 WIRE(PN202) 85kHz±5kHz(Auto Reverse) Record/Playback PN202 Frequency Counter Head and Pause Mode Test Tape Unit MTT-5511 Record/Playback head Figure 3. Record Bias Adjustment Connection Diagram 4.

  • Page 9: Troubleshooting

    TROUBLESHOOTING I CD SECTION CD PART CD Function Select Is power turned ON? Check power supply circuitry. Does initial reading occur? Check laser circuitry. Check focusing circuit. Check disc. Can disc be palyed? Check tracking servo circuitry. Is audio output supplied? Check Audio circuitry.
  • Page 10 If initial reading is not carried out (with disc) Does disc motor rotate? Does laser light? Is signal output, at Is RF waveform Is tracking servo Is signal output at • IC501 defective. IC501 Pin output? operating? (TEO)? • Connector Is the lower enve- (FEO) defective.
  • Page 11 When laser does not light. Is below signal “L” at PN806 (LDON)? Has Pick-up returned to the Are data transferred from • IC301 Defective. innermost position? IC301 Pin Is below signal output at IC503 • IC502, 503 defective. Does Voltage appear at PN 806 Pin (LOW) &...
  • Page 12 When laser lights. • IC501 defective. Is signal output at focus search Do lenses move up and down? terminal? • FOCUS Line short. IC501 pin (FEO) Is signal output at PN801 Pin • IC503 defective. lnsert disc and in the case of •...
  • Page 13 Is RFO signal output? IC501 Pin • IC501 defective. • Pick-up defective. • Connector defective. Is FZC signal output at IC501 When FOK focus • IC502 defective. Servo Conform by FZC signal ISTAT(SENSE) Is MDP signal outut by IC502 • IC502 defective. Has voltage at disc motor? •...
  • Page 14 MPEG PART TROUBLESHOOTING I MPEG PART 1. Is power supplied to MPEG PART IC (2.8V, 5V) 1) 5V : IC801, IC802 pin 81,IC803, IC804 2) 2.8V : IC802 pins 1, 31 ,51 2. NO VIDEO 1) check the 27 MHz (X801) 2) check the MPEG RESET - IC 801 pin 13, 24, IC802 pin 29 3) check the communication line [FRONT MICOM (IC301)
  • Page 15 P-SENS PART Does 5V appear at ZD703? Check the waveform of D703 (+). Replace the D703 Check the pattern of Check the R768 and IC301 Pin replace ZD703. VKK PART Does DC - 33V appear at PN302 Pin Dose -33V appear at ZD704(-) Check the -33V (LOW) of C769(-)
  • Page 16 Power Circuit (Power Circuit) Check the Fuse Replace the Fuse Check the DC output Check the AC output of CN701 Pin 1, 5 Replace the Transformer of C777(+), C778(-) Replace the D720 Check the DC power input of IC704 Check the AC output of CN701 Pin 7, 10 Replace the Transformer Check or Replace the D708,D709,...
  • Page 17 Audio abnormal Check the output of IC702 Pin 26, 27 Refer to IC702 Troubleshooting Check the input of IC701, IC751 Pin 3 Refer to Muting Troubleshooting Check the output of IC701 IC751 Pin 14 Check the power circuit Check the RY741 Refer to “SPK Relay Troubleshooting SPK Relay Troubleshooting...
  • Page 18 FUNCTION MODE Audio abnormal TAPE Is signal applied to IC702 Pin 7, 28 ? Refer to “IC202 Troubleshooting” Is signal applied to IC702 Pin 1, 26 ? Check the signal input of JK702 Is signal applied to IC702 Pin 3, 4 ? Check the signal of CN813 Pin 1, 3 or Refer to “CD Troubleshooting”...
  • Page 19 IC301 Troubleshooting Is power supplied to IC301 Pin 18, 46, 72 ? Refer to “Power Circuit Troubleshooting” Check the “5V” of IC301 Pin 11 Check the P-SENS Is oscillation of X301 normal ? Replace the X301 Is power supplied to IC301 Pin 12 ? ©...
  • Page 20 IC551 Troubleshooting Is power supplied to IC551 Pin 1 ? Refer to “Power Circuit Troubleshooting” Check the LOW & HIGH of IC551 Pin 10, 11, 15 (Pin Fanfare ON/OFF) Refer to “IC552 Troubleshooting” Replace the IC551 IC 702 Troubleshooting Is power supplied to IC702 Pin 24 ? Refer to “Power Circuit Troubleshooting”...
  • Page 21 IC701, IC751 Troubleshooting Check the signal input of Pin 3 Refer to “Muting Troubleshooting” Check the High(5V) of Pin 9, 10 Check the +5V of D791 Refer to “IC301 Troubleshooting” Check the Pin 8, 15 (-), & Pin 7, 13 (+) Check the PATTERN Refer to “Power Circuit Troubleshooting”...
  • Page 22 IC102 Troubleshooting Is power supplied to Pin 8 Refer to “Power Circuit Troubleshooting” Check the waveform of Pin 20, 21 Check FM(TUN101) & AM(L107) Replace the IC102 Check the output of Pin 16, 17 Check the “Low” of Pin 13 Refer to “IC103 Troubleshooting”...
  • Page 23 AM•COIL Troubleshooting Check the “High” of L107 Pin 2 Refer to “IC103 Troubleshooting” Check the oscillation of L107 Pin 13 Replace the L107 Refer to “IC102 Troubleshooting” Play Is Vcc supplied to IC202 Pin 18 ? Refer to “Power Circuit Troubleshooting” Check the signal output of IC202 Pin 5, 20 Is Deck Mecha normal ? Replace the Deck...
  • Page 24 REC (Q252, Q202 ON / R273, R223 High) Is signal supplied to IC202 Pin11, 14 ? Check the “Low” of Q253, Q203 “B” Refer to “IC203 Troubleshooting” Replace the Q253, Q203 Check the output of IC202 Pin9, 16 Check the Vcc power of IC202 Pin18 Check IC201 Pin6 (12V), 4 (High) Check power or Refer to “IC203 Troubleshooting”...
  • Page 25 Dubbing (“NORMAL or REC // HIGH”) Q252, 202 “OFF” // “ON” : R 273, 223 “LOW” // “HIGH” Check the “IC203 Troubleshooting” Q253, 203 “ON” // “OFF” : R 225, 275 “HIGH” // “LOW” Check the “IC203 Troubleshooting” Refer to REC - 2-19 -...

  • Page 26: Waveforms Of Major Check Point

    WAVEFORMS OF MAJOR CHECK POINT 1. HF signal (RF signal ) waveform 2. EFM signal (IC502 Pin )waveform (Test Point IC501 Pin ) during normal play during Normal Play 0.5V/Div. 2V/Div. 500nS/Div. 500nS/Div. 3. Focus coil drive waveform(PN801 Pin • Focus coil drive waveform(IC503 Pin ) and FOK •...

  • Page 27: Block Diagram

    BLOCK DIAGRAM NOTE: Warning NOTE: Parts that are shaded are critical With respect 1. Shaded(I) parts are critical for safety.Replace only to risk of fire or electrical shock. with specified part number. 2. Voltages are DC-measured with a digital voltmefer during Play mode.

  • Page 28: Schematic Diagrams

    SCHEMATIC DIAGRAMS • AMP/POWER SCHEMATIC DIAGRAM NOTE: NOTE: Warning Parts that are shaded are critical With respect 1. Shaded(I) parts are critical for safety.Replace only to risk of fire or electrical shock. with specified part number. 2. Voltages are DC-measured with a digital voltmefer during Play mode.
  • Page 29 • FRONT SCHEMATIC DIAGRAM 2-25 2-26...
  • Page 30 • TUNER/DECK SCHEMATIC DIAGRAM 2-27 2-28...
  • Page 31 • CDP SCHEMATIC DIAGRAM 2-29 2-30...
  • Page 32 • OVERALL BLOCK DIAGRAM 2-31 2-32...

  • Page 33: Printed Circuit Diargams

    PRINTED CIRCUIT DIAGRAMS • AMP/TUNER/POWER/DECK P.C. BOARD(SOLDER SIDE) NOTE: Warning Parts that are shaded are critical With respect to risk of fire or electrical shock. 2-33 2-34...
  • Page 34 • AMP/TUNER/POWER/DECK P.C. BOARD(COMPONENT SIDE) 2-35 2-36...
  • Page 35 • FRONT P.C. BOARD(COMPONENT SIDE) 2-37 2-38...
  • Page 36 • FRONT P.C. BOARD(SOLDER SIDE) 2-39 2-40...
  • Page 37 • POWER P.C. BOARD - 2-41 -...
  • Page 38 • CD MAIN P.C. BOARD - 2-42 -...

  • Page 39: Internal Block Diagram Of Ics

    INTERNAL BLOCK DIAGRAM OF ICs I LA1837 I BA3126N REC SW GND P/B SW CONT P/B SW REC SW I KIA6289N 3.3µF Rec Out Pre Out 10kΩ 10kΩ R . R 0.018µF µF 3.3µF 47µF 100Ω 9.1kΩ 6.8kΩ 180kΩ 1000 1.2µF µF 180kΩ...
  • Page 40 I KIA7805 P/PI ~ KIA7824P/PI INPUT OUTPUT - 2-44 -...
  • Page 41 I BU2090F Block diagram Control circuit DATA 12-bit shift register CLOCK Latch Output buffer (open drain) PIN DESCRIPTION Pin No. Pin name Function BU2090/F/FS BU2092/F BU2092/FV DATA Serial data input CLOCK Data shift clock input Data latch clock input parallel data output parallel data output parallel data output parallel data output...
  • Page 42 I TDA7294V C7 100nF C6 1000µF R3 22K +PWVs 22µF TDA7294 680Ω C1 470nF 22µF R1 22K IN+MUTE BOOTSTRAP R5 10K MUTE MUTE THERMAL STBY SHUTDOWN PROTECTION VSTBY STBY R4 22K STBY-GND -PWVs C3 10µF C4 10µF C9 100nF C8 1000µF I LC72131, 72131M - 2-46 -...
  • Page 43 I TDA7440D I FAN8033 - 2-47 -...
  • Page 44 PIN DESCRIPTION - 2-48 -...
  • Page 45 I CXA2581 - 2-49 -...
  • Page 46 PIN DESCRIPTION - 2-50 -...
  • Page 47 I CXA3023 - 2-51 -...
  • Page 48 PIN DESCRIPTION - 2-52 -...
  • Page 49 - 2-53 -...
  • Page 50 - 2-54 -...

  • Page 51: Repairs Regarding Cd Mechanism

    REPAIRS REGARDING CD MECHANISM IMPROVED METHOD - WHEN THE TRAY GEARS WERE DISTORTED 1. How to open the tray. In case of not suppling power push two hooks (H) of the base, and them open the tray. 2. How to improve the distorted gears. (1) Do the hole "C"...
  • Page 52 MEMO - 2-56 -...

  • Page 53: Section 3. Exploded Views

    SECTION 3. EXPLODED VIEWS NOTE) Refer to “SECTION 5 REPLACEMENT PARTS LIST” in order to look for the • CABINET AND MAIN FRAME SECTION part number of each part. - 3-1 - - 3-2 -...

  • Page 54: Tape Deck Mechanism: Auto Stop Deck(Optional)

    • TAPE DECK MECHANISM: AUTO STOP DECK(OPTIONAL) LOCA. NO PART NO. SPECIFICATION 6730R-G007A CWL44FF25 TOKYO PIGEON L-DOUBL 6768R-UP01A 50-093-4249 PIGEON UNIT PCB AS 6768R-BP01B 02-084-4202 PIGEON BELT / FELT C 6768R-BP01A 02-084-4204 PIGEON BELT / FELT C 6768R-AP01D 50-239-4027 PIGEON ARM CWL44 6768R-AP01E 50-239-4026 PIGEON ARM CWL44 6768R-SP01E...

  • Page 55: Tape Deck Mechanism: Auto Reverse Deck

    • TAPE DECK MECHANISM: AUTO REVERSE DECK LOCA. NO PART NO. SPECIFICATION 6730R-G007B CDM-H1323 CD CHAN 6768R-UP01A 50-093-4249 PCB AS 6768R-BP01B 02-084-4202 BELT/FELT 6768R-BP01A 02-084-4204 BELT/FELT 6768R-AP01D 50-239-4027 CWL44 6768R-AP01E 50-239-4026 ARM 6768R-SP01E 01-082-4654 SPRING 6768R-QP01A 50-093-4316 MOTOR 6768R-GP01A 50-093-4063 GEAR 6768R-SP01F 01-082-4598 SPRING 6768R-MP01C...

  • Page 56: Cd Mechanism

    • CD MECHANISM LOCA.NO PART NO. DESCRIPTION SPECIFICATION 4405RBE003C MECHANISM ASSY CDM-H1333 LGEHZ CD CHANGER (S 3041RB0002B BASE ASSEMBLY PU(F-576MV) 6717RCA001A PICK UP ASSY KSM-213VSCM SONY FRONT LOADING 3390SB0002A TRAY DISC (CDM-H1303) 4470SB0011A GEAR TRAY B (CDM-H1303) 4470SB0010A GEAR TRAY A (CDM-H1303) 4400SB0001B BELT TRAY(CDM-H1303)

  • Page 57: Section 4. Speaker

    DESCRIPTION SPECIFICATION REMARK 3701RM0007C NET ASSEMBLY JERSEY NET ASSY (FE-3785E/5765 3720RMF008C PANEL,FRONT FRONT PANEL(FE-3785/5765E) BK 6400RMXY01A SPEAKER,GENERAL (FE-376E) PIEZO LG 0OHM 0W 0DB 4930RM0005A HOLDER HOLDER PIEZO FE-376E 353M050C SCREW BH 3.5X16 FBK 6400W00005A SPEAKER,WOOFER CW-125B20L-2 SAMMI 6OHM 30/60W 353M025F...
  • Page 58 MEMO - 4-2 -...

Table of Contents