LG-FFH2850AX-cs-sm 维修电路原理图.pdf

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1、- 1- 1 -CONTENTSSECTION 1. GENERAL SERVICING PRECAUTIONS.1- 2 ESD PRECAUTIONS.1- 4 SPECIFICATIONS.1- 5SECTION 2. ELECTRICAL ADJUSTMENTS.2- 1 TROUBLESHOOTING.2- 3 WAVEFORMS OF MAJOR CHECK POINT.2- 8 BLOCK DIAGRAM.2- 9 SCHEMATIC DIAGRAMS.2- 11 WIRING DIAGRAM.2- 19 PRINTED CIRCUIT DIAGRAMS.2- 21 INTERN

2、AL BLOCK DIAGRAM OF ICs.2- 30SECTION 3. EXPLODED VIEWS 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- 7SECTION 4. SPEAKER.4-1SECTION 5. REPLACEMENT PARTS LIST.5-1RadioFans.CN 收音机爱 好者资料库SECTION 1. GEN

3、ERALSERVICING PRECAUTIONSNOTES REGARDING HANDLING OF THE PICK-UP1. Notes for transport and storage1) 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 notes1) The pick- up incorpo

4、rates 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 andimpact. If it is subjected to strong pressure or impact, the result may be an operational malfunction and/orda

5、mage to the printed- circuit board.3) Each and every pick- up is already individually adjusted to a high degree of precision, and for that reasonthe adjustment point and installation screws should absolutely never be touched.4) Laser beams may damage the eyes!Absolutely never permit laser beams to e

6、nter 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 surfaceIf there is dust on the lens surface, the dust should be cleaned away by using an air bush (such as usedfor camera lens). The lens is held by a delicate spr

7、ing. When cleaning the lens surface, therefore, acotton 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. (Donot use any other liquid cleaners, becau

8、se they will damage the lens.) Take care not to use too much ofthis alcohol on the swab, and do not allow the alcohol to get inside the pick- up.- 1- 2 -Storage in conductive bagDrop impactNEVER look directly at the laser beam, and dont letcontact fingers or other exposed skin.MagnetHow to hold the

9、pick- upPressurePressureCotton swabConductive SheetRadioFans.CN 收音机爱 好者资料库NOTES REGARDING COMPACT DISC PLAYER REPAIRS 1. Preparations1) Compact disc players incorporate a great many ICs as well as the pick- up (laser diode). Thesecomponents are sensitive to, and easily affected by, static electricit

10、y. If such static electricity is highvoltage, 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 mustbe taken, therefore, to avoid repair or storage where the temperat

11、ure of humidity is high, where strongmagnetism is present, or where there is excessive dust.2. Notes for repair1) Before replacing a component part, first disconnect the power supply lead wire from the unit2) All equipment, measuring instruments and tools must be grounded.3) The workbench should be

12、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 isbecause 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)

13、Workers should be grounded by an armband (1M)6) Care should be taken not to permit the laser pick- up to come in contact with clothing, in order to preventstatic electricity changes in the clothing to escape from the armband.7) The laser beam from the pick- up should NEVER be directly facing the eye

14、s or bare skin.CLEARING MALFUNCTIONYou 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 thevolume knob for more than 3 seconds. If you reset your unit, you m

15、ust 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.- 1- 3 -ArmbandConductiveSheetResistor(1 Mohm)Resistor(1 Mohm)VOLUME KNOBUPD

16、OWNVOLUMERESET jump wireESD PRECAUTIONSElectrostatically Sensitive Devices (ESD)Some semiconductor (solid state) devices can be damaged easily by static electricity. Such componentscommonly are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integratedcircuits a

17、nd some field- effect transistors and semiconductor chip components. The following techniques shouldbe 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 offany elect

18、rostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear acommercially available discharging wrist strap device, which should be removed for potential shock reasonsprior to applying power to the unit under test.2. After removing an electrical assembly equipped wi

19、th ESD devices, place the assembly on a conductivesurface 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 dev

20、ices not classified as anti- static cangenerate electrical charges sufficient to damage ESD devices.5. Do not use freon- propelled chemicals. These can generate electrical charges sufficient to damage ESDdevices.6. Do not remove a replacement ESD device from its protective package until immediately

21、before you are readyto install it. (Most replacement ESD devices are packaged with leads electrically shorted together byconductive foam, aluminum foil or comparable conductive materials).7. Immediately before removing the protective material from the leads of a replacement ESD device, touch theprot

22、ective 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 OTHERSAFETY PRECAUTIONS.8. Minimize bodily motions when handing unpackaged replacement ESD devices. (Otherwise harmless motionsu

23、ch as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor cangenerate static electricity sufficient to damage an ESD device).CAUTION. GRAPHIC SYMBOLSTHE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, ISINTENDED TO ALERT THE SERVICE P

24、ERSONNEL TO THE PRESENCE OF UNINSULATED“DANGEROUS VOLTAGE” THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISKOF ELECTRIC SHOCK.THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THESERVICE PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICELITERATURE.- 1

25、- 4 -SPECIFICATIONS1. AMP SECTION1) Power Output (6 , 2 channel, T.H.D. 10%).20W+20W2) T.H.D.0.15%3) Frequency Response (- 3dB down).42Hz25kHz4) Signal- to- noise Ratio.80dB5) Input Sensitivity AUX.40050mV6) Channel Difference 1kHz.2dB2. TUNER SECTION1) FM1) Frequency Range.87.5MHz108MHz2) Intermedi

26、ate Frequency.10.7MHz3) Sensitivity (90/98/106MHz).12dB4) Signal- to- noise Ratio 98.1MHz(Mono/Stereo).64dB/55dB5) Image Rejection 106.1MHz.18dB6) IF Rejection 90.1MHz.60dB7) Distortion 98.1MHz(Mono/Stereo).1.2/1.2%8) Frequency Response (- 3dB).60Hz10kHz9) Stereo Separation (100Hz/1kHz/10kHz).25dB2)

27、 AM(MW)1) Frequency Range.522kHz1611kHz2) Intermediate Frequency.455kHz3) Usable Sensitivity.55dB/m4) Image Rejection (1404kHz).20dB5) IF Rejection (603kHz).40dB6) Selectivity (1008kHz).23dB7) Signal- to- noise Ratio (1008kHz).35dB8) Distortion (1008kHz).1.5%9) Frequency Response (1008kHz).100Hz1800

28、Hz3) SW(OPTIONAL)1) Frequency Range.5.8MHz18MHz2) Intermediate Frequency.450kHz3) Usable Sensitivity.40dB/m4) Signal To Noise Ratio.35dB5) Distortion .3%4) LW(OPTIONAL)1) Frequency Range.153kHz281kHz2) Intermediate Frequency.450kHz3) Usable Sensitivity.65dB4) Signal To Noise Ratio (200kHz).28dB5) Di

29、stortion (200kHz).3%- 1- 5 -3. TAPE DECK SECTION1) Tape Speed (MTT- 111) / Normal Speed.4.75cm/sec2) Wow Flutter (MTT- 111) .0.25%3) Fast Forward and Rewind Time (C- 60).120sec4) Frequency Response (6dB range).250Hz8kHz5) Signal- to- noise Ratio (Playback/Record).43dB/43dB6) Distortion (Playback/Rec

30、ord).3% / 4%7) Crosstalk (Playback: 1kHz).55dB8) Channel Separation (Playback: 1kHz).50dB/45dB9) Erase Ratio.55dB4. COMPACT DISC PLAYER SECTION1) Frequency Response (40Hz- 18kHz).+0.5/- 3.0dB2) Signal- to- noise Ratio (1kHz).70dB3) Dynamic Range (1kHz).70dB4) T.H.D. (1kHz).0.2%5) Separation (100Hz/1

31、kHz/10kHz).45dB/47dB/40dB6) Access Time (Short / Long).2sec/6sec5. GENERAL1) Power requirement.Refer to the back panel of unit2) Power consumption.60W3) Dimension (W x H x D).180 x 248 x 241.3 (mm)NOTE : Specification are subject to change without notice in the course of product improvement.- 1- 6 -

32、 2- 1 -TAPE DECK ADJUSTMENT1. AZIMUTH ADJUSTMENTFigure 1. Azimuth Adjustment Connection DiagramCH1 CH2Speaker OutPlayback ModeHeadTest TapeMTT- 114L chR chGNDDual- tracesynchroscopeElectronicVoltmeterL outR outUnitSECTION 2. ELECTRICALADJUSTMENTSThis set has been aligned at the factory and normally

33、will not require further adjustment. As a result, it is notrecommended that any attempt is made to modificate any circuit. If any parts are replaced or if anyone tamperswith the adjustment, realignment may be necessary.IMPORTANT1. Check Power- source voltage.2. Set the function switch to band being

34、aligned.3. Turn volume control to minimum unless otherwise noted.4. Connect low side of signal source and output indicator to chassis ground unless otherwise specified.5. Keep the signal input as low as possible to avoid AGC and AC action.Deck ModeTest TapeTest PointAdjustmentAdjust forPalybackMTT-

35、114Speaker OutDECK ScrewMaximumAzimuth Screw2. RECORD BIAS ADJUSTMENTHeadUnitPN202GNDRecord/PlaybackheadTest TapeMTT- 5511Record/Playbackand Pause ModeFrequency CounterDeck ModeTest TapeTest PointAdjustmentAdjust forRec/PauseMTT- 5511ERASE HEADL20160kHz5kHz (Auto stop)WIRE(PN201)85kHz5kHz(Auto Rever

36、se)Figure 2. Record Bias Adjustment Connection Diagram- 2- 2 -3. TUNER ADJUSTMENTFigure 3. Tuner(S curve) Adjustment Connection DiagramUnitSignal GeneratorGNDElectronicOSCILLOSCOPEFM AntennaTerminalSpeakerItemTest PointAdjustmentAdjust forDC VoltageCheck Point TP1, TP2L1010V50mV(FM)- 2- 3 -TROUBLESH

37、OOTINGTurn power on.Is power on?Does initial read work?Does it play?Does it output audio?Check power supply circuit.(Check PN 501)Check laser circuit.Check focus circuit.Check disc.Check tracking servo circuit.Check audio circuit.OKYESYESYESYESNONONONO- 2- 4 -Fails to initial read 1.3VABYESYESYESYES

38、YESYESYESYESNONONONONONONONONONODoes laser light?Disc motor turns.Does RFwaveformappear?Test Pin(RF)Does trackingservo work?Lower envelopeof Test Pin(RF)waveform is flat.Does signalappear at TestPin(TEO)?Does signal appear at IC 502Pin and Pin ?Does GFS (IC503 pin 25)show as below?Is rotation normal

39、?Is there no dropout of RFsignal?Does TE2 signalappear at pinof IC501?Defective IC801, pick upand/or openwire.Detective pattern.Defective IC 501and/or IC 502Defective pick- upand/or connector.Defective IC 503.Scratch in discinitial read area.Defective pick- upadjustment focus offset.532627- 2- 5 -A?

40、NONONONONONOLaser does not light.Is “3.5V” applied to pin of IC 501?Is power supplied to laser Q501?(Q 501 collector: about 1.8V)Does laser current flow?1.0V across R507Is data transferred fromMICOM IC ?Does voltage appear at IC502 pin , ?Defective MICOM.Defective MICOM.Defective connector.Defective

41、 IC 501, 502 Defective slide motor and/orconnector.Defective LMT SW and/orconnector.Defective Q 501 and/or laser.Defective laser and/orconnector.Did pickup return toinnermost circular?Does it stop at inner pickcircular after shift?Is defect output from LMSW applied to pin ofPN503?R5071.0VR5071.0VYES

42、YESYESYESOPENCLOSEYESYESYESYESYESYES7017185- 2- 6 -BCDoes lens move up/down?Does IC 501 out focussearch signal?IC 501 pin (FEO)Is focus search signalapplied to pin , ofPN502?Laser lights.Confirminitialread withdiscDefective IC501 Defective IC502 Defective IC 501.Open activator and/orconnector.Open c

43、onnector and/ordefective IC 501.Incorrect turntable height.Degraded laser diode.Does Test Pin RF signal appear even inlow level?Is laser output adjustment correct?Does FOK(focus ok) signal appear?YESYESYESYESYESYESIC501 Pin (RF)IC501 pin (FOK)NONONONONONO4813164074- 2- 7 -FERISTAT(SENSE)?CStart mode

44、Does FE1 signal appear? IC 501 pinDoes FZC signal (focus zero cross signal)appear at pin of IC 501, ISTAT (SENSE)terminal?Does SMON signal appear at pin of IC 503?Does SMPO signal appear at pin of IC 503?Is drive voltage applied to disk motor?Defective IC 501.Open pick diodeDefective IC 501.Defectiv

45、e Pattern between IC 501 andIC 502.Defective IC 501, 502 and/orperipheral circuit.Defective disk motor and/or insulation.(Focus servo turnsON by FZC signalof FOK mod.)NONONONOYESYESYESYESYES73753159- 2- 8 -(CH1)(CH2)WAVEFORMS OF MAJOR CHECK POINT1. HF signal (RF signal ) waveform(Test Point) during

46、normal play 2. EFM signal (pin IC 501)waveformduring Normal Play3. Focus coil drive waveform(Pin NO 1, 2 of IC 502)When focus search failed or there is no disc on the trayFocus coil drive waveform(pin NO 1, 2 of IC 502) andFOK (pin NO of IC 501) when focus search isaccomplished4. Tracking coil drive

47、 waveform (pin NO , of IC 502)and TEO during track traverse(1) When time division is 20nS/div(2) When time division 0.5nS/div.(During forward track traverse)(3) When time division is 0.5nS/div.(During backward Track Traverse)5. Feed motor drive waveform(pin NO 11, 12 of IC 502)During normal playCH1

48、: FOCUS COIL DRIVESIGNAL 2V/Div.CH2 : FOAKCH1 : TEO(Test Point)1V/Div.CH2 : TRACKING COIL DRIVESIGNAL 2V/Div.(CH1 : TEO(Test Point)1V/Div.CH2 : TRACKING COIL DRIVESIGNAL 2V/Div.(CH1 : TEO(Test Point)1V/Div.CH2 : TRACK COIL DRIVESIGNAL 2V/Div.(402633270.5V/Div.500nS/Div.(2V/Div.500nS/Div.(0.5V/Div.50

49、0nS/Div.OVOVOV(CH1)(CH2)(CH1)(CH2)(CH2)OVOVOVOVOVOVOVOVOV2-9 2-10 BLOCK DIAGRAMNOTE:1. Shaded(I) parts are critical for safety.Replace onlywith specified part number.2. Voltages are DC-measured with a digital voltmeferduring Play mode.NOTE: WarningParts that are shaded are critical With respectto ri

50、sk of fire or electrical shock.SCHEMATIC DIAGRAMS MAIN SCHEMATIC DIAGRAM2-11 2-12 NOTE:1. Shaded(I) parts are critical for safety.Replace onlywith specified part number.2. Voltages are DC-measured with a digital voltmeferduring Play mode.NOTE: WarningParts that are shaded are critical With respectto