JVC-PCX270-cs-sm维修电路原理图.pdf

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1、 S E R V I C E M A N U A L MODEL : PC-X270 ( C ) AM/FM RADIO CASS CD PORTABLE SYSTEM RadioFans.CN 收音机爱 好者资料库 MATESTAR ELECTRONICS LTD. PERFORMANCE SPECIFICATIONS Date: 7 May , 2003 Model : PC-X270 Band: AM / FM (PLL RADIO) CD CASSETTE System PageTotal6 Pages GENERAL TEST CONDITION Output Load 3 ohm

2、non-reactive Reference Output: 250 mW Input Signal Source: IRE LOOP for AM 75 ohm dummy for FM Modulation : 30% 400 Hz for AM 22.5 KHz Deviation 1 KHz for FM 75KHz Modulation for FM MPX Remarks DC : 12V AC : 120V 60Hz * * * Subject to change without notice . Prepared byApproved by page 1 RadioFans.C

3、N 收音机爱 好者资料库 ? ? PERFORMANCE SPECIFICATIONS MODEL NO : PC-X270 Amplitude Modulation ( AM ) Section Test Item Unit Nominal Limit#1#2 A.01 Tuning RangeLOWKHz520+/-5 HIGHKHz1710+/-5 A.02 I.F. Frquency600KHzKHz450+/-5 A.03 Sensitivity (AM Loop ANT.) (LOW TP)600KHzdB/m5868 S/N 20dB (MID TP)1000KHzdB/m586

4、6 (HIGH TP)1400KHzdB/m5866 A.04 Image Rejection1000KHzdB 1400KHzdB3730 A.05 S/N Ratio at 100dB/m Input600KHzdB3530 1000KHzdB3530 1400KHzdB3530 A.06 I.F. Rejection(MW)600KHzdB4840 A.07 AM Whistle Modulation910/1350KHz%-15 A.08 Selectivity (+/-10KHz) (ACA)600KHzdB 1000KHzdB A.09 AGC Figure of Merit (1

5、26dB)1000KHzdB4035 A.10 Audio Response -6dB (AM:1000KHz)LOWHz70125 HIGHKHz2K52K A.11 Distortion30% at Ref.1000KHz%13 60% at Ref.1000KHz%510 A.12 Modulation Hum (AC)1000KHzdB5040 A.13 Overload (M=80% THD=10%)1000KHzmV/m100 A.14 Min. Volume Hum and NoisemV0.71.2 A.1510% THD Power(Mod:80%)(1-CH Load On

6、ly)( AC )W5 A.16 Max. Vol. Audio Power Output (80% Mod)1000KHzW A.17 6dB Bandwidth at 20dB S/N1000KHzKHz4+/-3 A.18 Auto Search Threshold600KHzdB/m6068 1000KHzdB/m6066 1400KHzdB/m6066 A.19 OSC Dropout Voltage Max. Power (DC)1000KHzV8.410.8 Fial Out Valtage (AC)1000KHz%70 page 2 ? ? PERFORMANCE SPECIF

7、ICATIONS MODEL NO : PC-X270 Frequency Modulation ( FM ) Sectionn Test Item Unit Nominal Limit#1#2 F.01 Tuning RangeLOWMHz87.9+/-0.1 HighMHz107.9+/-0.1 F.02 Frequency Step200/100HzKHz F.03 I.F Frequency90.1MHzMHz10.7+/-0.09 F.04 Sensitivity at -30dB S/N (MONO)90.1MHzdB/uM2028 98.1MHzdB/uM2028 106.1MH

8、zdB/uM2028 F.05 3 dB Limit Sens98.1MHzdB1525 F.06 Stereo Threshold (Dev 75KHz)98.1MHzdB1525 F.07 Overload98.1MHzdB110 F.08 Image Rejection90.1MHzdB 106.1MHzdB2518 F.09 I.F. Rejection90.1MHzdB5040 F.10 AM Suppression98.1MHzdB3024 F.11 Spurious Suppression98.1MHzdB F.12 Selectivity at 98.1MHz +/-400KH

9、z98.1MHzdB F.13 Audio Response -6dB 98.1MHzHz/KHz60/4K5100/4K F.14 Channel Separation (1KHz)98.1MHzdB3020 F.15 Total Harmonic Distortion (60dB) Mono Ref.22.5KHz%13 Max Powe75KHz%1030 F.16 Signal to Noise Ratio (Input 60dB)90.1MHzdB 98.1MHzdB4540 106.1MHzdB STEREO S/N(INPUT 60dB) W/F B.P.F98.1MHzdB40

10、30 F.17 Auto Search Threshold98.1MHzdB2530 106.1MHzdB F.18 Modulation Hum (AC)98.1MHzdB4540 F.19 AFC Holding Range98.1MHzKHz F.20 Min. Volume Hum ( 2 ) R/P swith in recording state; ( 3 ) Adjusting T801 use a plastic screwdriver, AC bias frepuency;61+-1KHZ. 3 TAPE SPEED ADJUSTMENT ( 1 ) Insert the t

11、est tape(MTT-111N,3,000 HZ) ( 2 ) Press the PLAY button. ( 3 ) Use a flat-tip screwdriver to turn the SF201 adjust SF201 so that the frequency counter become 3,000Hz TAPE HEAD AND SPEED ADJUSTMENT DIAGRAM CASS DECK A DECKB DECK A P HEAD L. SW A L. SW E HEAD P/R HEAD page 3 Tape recorder section Meas

12、urementStandardAdjusting conditionsValuespositions ConfirmationTest tape1 Playback the test tape TCC-182A (8KHz)MaximumAdjust the head of head angle:TA-182A(8KHz)2 With the recording & playback mechanism, outputazimuth screw Measurement output adjust the head azimuth screw so that theonly when the t

13、erminal left and right output levers becomehead has been :Speaker terminal maximum, After adjustment, lock the headchanged Sparker R azimuth at least by half turn. (Load resistance:3) :Headphone terminal ConfirmationTest tapeAdjust SF201 so that the frequency counterTape speedSF201 of tape speed:TCC

14、-112(3000Hz)reading becomes 3,010Hz +/-15Hz whenof deck playing back the test tape TCC-112 (3000Hz) with:3,010Hz Measurement outputplayback and recording mechanism after+/-15Hz terminalending forward winding if the taoe. :Headphone terminal Reference Values for Confirmation Items MeasurementStandard

15、Adjusting conditionsValuespositions Wow & flutterTest tapeWhen the test tape TCC-112 (3000Hz) has been0.25% or :TCC-112(3000Hz)played back with the recording and playbackless mechanism at the beginning of forward(WRMS) Measurement outputwinding, the frequency counter reading of terminalwow & flutter

16、 should be 0.25% or less :Headphone terminal(WRMS). Electrical Performance MeasurementStandardAdjusting conditionsValuespositions Adjustment of Mode:Forward or1 With the recording and playback recording bias reverse mode mechanism, load thd test tapes current Recording mode TDK-60 , and set the mech

17、anism to the recording270A (Reference Test tape and pausing condition in advance . +/-0.5A Value)TDK-60 Measurement output2 After connecting 100in series to the terminal recorder head, measure the bias current :Both recording and with a valve voltmeter at both of the headphone terminals terminals IT

18、EMSMeasurement method Measurement methodItems ITEMSMeasurement method page 4 Adjustment ofReference frequency1 with the recording and playbackOutput recording and:1KHz and 8KHz mechanism, load the test tapes (TDK-60)deviation playback (REF.:-20dB) and set the mechanism to thebetween frequencyTest ta

19、pe recording and pausing condition in 1KHz and characteristicsTDK-60 advance8KHz Measurement input2 While repetitively inputting the reference:-1dB +/-2dB terminal frequency signal of 1KHz and 10KHz from :OSC IN OSC IN, record and playback the tape. 3 While receding and playback the test tape in TYP

20、E , adjust for Lch and for Rch so that the output deviation between 1KHz and 8KHz must be in -1dB Reference Values for Electrical Function Confirmation Items MeasurementStandardAdjusting conditionsValuespositions RecordingForward or reverse1 While changing over to and form BIAS 161KHz biasTest tape

21、and 2, confirm that the frequency is+/-1KHz frequencyTDK-60 changed Measurement2 With the recording and playback terminal : BIAS TP on mechanism, load the test tape. P.C. board (TDK-60 ) , and set the mechanism to the recording and pausing condition in advance. 3 Confirm that the BIAS TP frequency o

22、n the P.C. board is 61KHz +/-1KHz ItemsMeasurement method page 5 Flow of functional operation until TOC read Check Point Check that the voltage at the pin 16 of IC903 is OV (a moment)? Check that the voltage at the pin64 of IC901 + side is + 5V? Confirm that the Focus error s-cuve signal at the pin2

23、0 of IC901 is approx.2V p-p Tracking error waveform at TOC readingConfirm that the signal from pin27 IC901 is 0V as a accelerated pulse during approx.400ms Confirm the waveform of the Tracking error signal at the pin 7 of IC901 (See fig-1) Confirm the eys-pattern at the lead of TP1 Power ONPower Key

24、Slider turns REST SW ON. Automatic tuning of TE offset Laser ON Detection of disc Automatic tuning of Focus offset Automatic measurement of Disc is rotated Focus servo ON (Tracking servo ON) Automatic measurement of Automatic tuning of Tracking error balance Automatic tuning of Focus error balance A

25、utomatic tuning of Focus error gain Automatic tuning of Tracking error gain TOC reading Play a disc Approx. 3sec pin 7 of IC901(TE) Approx. 1.8V Tracking servo off status Tracking servo on status Disc to be braked to stop TOC reading finishes Disc status to rotate Automatic measurement of TE amplitude and automatic tuning of TE balance 500mV/div 2mS/div Fig.1 VREF