JVC-MXG70-cs-sm维修电路原理图.pdf
SERVICE MANUAL No.20920 Mar. 2001 COPYRIGHT 2001 VICTOR COMPANY OF JAPAN, LTD. MX-G70 COMPACT COMPONENT SYSTEM MX-G70 Area Suffix J C U.S.A. Canada Safety precautions Important for laser products Warnings and Cautions Preventing static electricity Importance administering point on the safety Disassembly method 1-2 1-3 1-3 1-4 1-5 1-6 Adjustment method Flow of functional operation until TOC read Maintenance of laser pickup Replacement of laser pickup Description of major ICs 1-26 1-30 1-31 1-31 1-32 Contents PLAY TW2111A, Reverse ; TW2121A Fast Forward and Rewind ; TW2231A 9. Test disc : CTS-1000(12cm),GRG-1211(8cm) 10. Jitter meter Measurement conditions Power supply voltage AC120V(60Hz) Measurement output terminal : Speaker out :TP101(Mesuring for TUNER/DECK/CD) :Dummy load 6ohm Radio input signal AM modulation frequency : 400Hz Modulation factor : 30% FM modulation frequency : 400Hz Frequency displacement : 22.5kHz Frequency Range AM531kHz1710kHz FM87.5MHz108MHz Standard measurement positions of volume and switch Power : Standby (Light STANDBY Indicator) Sub woofer VOL. : Minimum Sound mode : OFF Main VOL. : 0 Minimum Traverse mecha set position : Disc 1 Precautions for measurement 1. Apply 30pF and 33kohm to the IF sweeper output side and 0.082 F and 100kohm in series to the sweeper input side. 2. The IF sweeper output level should be made as low as possible within the adjustable range. 3. Since the IF sweeper is a fixed device, there is no need to adjust this sweeper. 4. Since a ceramic oscillator is used, there is no need to perform any MPX adjustment. 5. Since a fixed coil is used, there is no need to adjust the FM tracking. 6. The input and output earth systems are separated. In case of simultaneously measuring the voltage in both of the input and output systems with an electronic voltmeter for two channels, therefore, the earth should be connected particularly. 7. In the case of BTL connection amplifier, the minus terminal of speaker is not for earthing. Therefore, be sure not to connect any other earth terminal to this terminal. This system is of an OTL system. MX-G70 1-27 Arrangement of adjusting positions Cassette mechanism section (Mechanism A section)Cassette mechanism section (Back side) Cassette Mechanism Unit Section Head azimuth adjusting screw (Forward side) Head azimuth adjusting screw (Reverse side) Head azimuth adjusting screw (Forward side) Head azimuth adjusting screw (Reverse side) Playback head Playback, recording and eraser heads or playback head Tape speed ADJ Bias ADJ L Bias ADJ R MX-G70 1-28 1.Playback the test tape TMT7036(10kHz). 2.With the playback mechanism or recording & playback mechanism, adjust the head azimuth screw so that the forward and reverse output levels become maximum.After adjustment,lock the head azimuth at least by half a turn. 3.In either case,this adjustment should be performed in both the forward and reverse directions with the head azimuth screw. Adjust VR301 so that the frequency counter reading becomes 3,000Hz 60Hz when playing back the test tape VTT712(3kHz)with the playback mechanism or playback and recording mechanism after ending forward winding of the tape. Confirmation of head angle Confirmation of tape speed Test tape :TMT7036(10kHz) Measurement output terminal :Speaker terminal Speaker R (Load resistor:6 ) :Headphone terminal Test tape :VTT712(3kHz) or TMT7036(3kHz) Measurement output terminal :Headphone terminal Maximum output Tape speed of decks (A and B) :3,000Hz 60Hz Adjust the head azimuth screw only when the head has been changed. VR301 ItemsMeasurement conditions Measurement method Standard values Adjusting positions Tape recorder section ItemsMeasurement conditions Measurement method Standard values Adjusting positions After setting to the double speed motor, confirm that the frequency counter reading becomes 4,800+400/-300Hz when the test tape VTT712 (3kHz) has been play back with the playback mechanism. When the test tape VTT712(3kHz) has been played back with the playback mechanism or recording and playback mechanism at the beginning of forward winding, the frequency counter reading of the difference between both of the mechanisms should be 6.0Hz or less. When the test tape VTT712(3kHz) has been played back with the playback mechanism or recording and playback mechanism at the beginning of forward winding the frequency counter reading of wow & flutter should be 0.25% or less(WRMS). Double tape speed Difference between the forward and reverse speed. P.mecha and R/P mecha speed Wow & flutter Test tape :TMT7036(10kHz) Measurement output terminal :Speaker terminal Speaker R (Load resistance:6 ) measurement output terminal :Headphone terminal Test tape :TMT7036(10kHz) Measurement output terminal :Headphone terminal 4,800+400/ -300Hz 60Hz or less with in 0.25% JIS(WTD) Playback mechanism side Both the playback and recording & playback mechanism Both the playback and recording & playback mechanism Reference values for confirmation items MX-G70 1-29 ItemsMeasurement conditions Measurement method Standard values Adjusting positions 1.With the recording and playback mechanism, load the test tapes(AC-225 to TYP ),and set the mechanism to the recording and pausing conditions in advance. 2.After connecting 100 in series to the recorder head,measure the bias current with a valve voltmeter at both of the terminals. 3.After resetting the PAUSE mode,start recording. At this time,adjust VR101 for LcH and VR201 for RcH so that the recording bias current values become 4.0 A (TYP ). 1.With the recording and playback mechanism,load the test tape(AC-225 to TYP ),and set the mechanism to the recording and pausing condition in advance. 2.While repetitively inputting the reference frequency signal of 1kHz and 10kHz from OSC IN, record and playback the test tape. 3.While recording and playing back the test tape in TYP ,adjust VR101 for LcH and VR201 for RcH so that the output deviation between 1kHz and 10kHz becomes -1dB 2dB. Adjustment of recording bias current (Reference value) Adjustment of recording and playback frequency characteristics *Mode : Forward or reverse mode *Recording mode *Test tape : AC-225 Measurement output terminal :Both recording and headphone terminals Reference frequency :1kHz and 10kHz (REF:-20dB) Test tape :TYP AC-225 Measurement input terminal :OSC IN AC-225 :4.20 A Output deviation between 1kHz and 10kH :-1dB 2dB LcH :VR101 RcH :VR201 LcH :VR101 RcH :VR201 Electrical performance ItemsMeasurement conditions Measurement method Standard values Adjusting positions 1.With the recording and playback mechanism. load the test tape (AC-225 to TYP ),and set the mechanism to the recording and pausing conditions in advance. 2.Confirm that the BIAS TP frequency on the P.C.board is 100kHz 6kHz. 1.With the recording and playback mechanism, load the test tapes(AC-225 to TYP ),and set the mechanism to the recording and pausing condition in advance. 2.After setting to the recording conditions,connect 1M in series to the eraser head on the recording and playback mechanism side,and measure the eraser current from both of the eraser terminal. Recording bias frequency Eraser current (Reference value) *Recording and playback side forward or reverse *Test tape :TYP AC-225 *Measurement terminal BIAS TP on P.C.board *Recording and playback side forward or reverse *Recording mode *Test tape :AC-225 Measurement terminal Both of the eraser head 100kHz +9kHz -7kHz TYP :75mA Reference values for electrical function confirmation items MX-G70 1-30 Flow of functional operation until TOC read Slider turns REST SW ON. Automatic tuning of TE offset Laser ON Detection of disc Automatic measurement of Focus S-curve amplitude Automatic tuning of Focus offset Disc is rotated Focus servo ON (Tracking servo ON) Automatic tuning of Tracking error balance Automatic measurement of Tracking error amplitude Automatic tuning of Focus error balance Disc to be braked to stop Tracking servo on states Tracking servo off states Disc states to rotate TOC reading finishes Automatic measurement of TE amplitude and automatic tuning of TE balance 500mv/div 2ms/divFig.1 Approx.3sec pin 25 of IC601(TE) Approx 1.8V VREF Tracking error waveform at TOC reading Power ON Play Key Confirm that the Focus error S-cuve signal at the pin28 of IC651 is approx.2Vp-p Confirm that the signal from pin24 IC651 is 0V as a accelerated pulse during approx.400ms. Confirm the waveform of the Tracking error signal. at the pin 25 of IC601 (R604) (See fig-1) Automatic tuning of Focus error gain Automatic tuning of Tracking error gain TOC reading Play a disc Confirm the eys-pattern at the lead of TP1 Confirm that the voltage at the pin5 of CN801 is HLH. Check Point Check that the voltage at the pin40 of IC651 is + 5V? MX-G70 1-31 Turn off the power switch and, disconnect the power cord from the ac outlet. Replace the pickup with a normal one.(Refer to Pickup Removal on the previous page) Plug the power cord in, and turn the power on. At this time, check that the laser emits for about 3seconds and the objective lens moves up and down. Note: Do not observe the laser beam directly. Play a disc. Check the eye-pattern at TP1. Finish. Maintenance of laser pickup (1) Cleaning the pick up lens Before you replace the pick up, please try to clean the lens with a alcohol soaked cotton swab. (2) Life of the laser diode When the life of the laser diode has expired, the following symptoms will appear. 1. The level of RF output (EFM output : ampli tude of eye pattern) will below. Is the level of RFOUT under 1.25V 0.22Vp-p? Replace it. NO YES O.K (3) Semi-fixed resistor on the APC PC board The semi-fixed resistor on the APC printed circuit board which is attached to the pickup is used to adjust the laser power. Since this adjustment should be performed to match the characteristics of the whole optical block, do not touch the semi-fixed resistor. If the laser power is lower than the specified value, the laser diode is almost worn out, and the laser pickup should be replaced. If the semi-fixed resistor is adjusted while the pickup is functioning normally, the laser pickup may be damaged due to excessive current. Replacement of laser pickup MX-G70 1-32 1 2 3456789 1011 12 13141516171819 2021 22 23 24 AMP Pre Source CTRL AMP ALC ALC AMP AMP EQ CTRL ALC REPPLE REJ Pre Pre L1 L2 R1R2NF2 NF1OUT1 OUT2 EQ1 EQ2 CTL2 CTL1 RIN2 RIN1 RNF2 RNF1 ROUT2 ROUT1 LCLPFGND EQ CTLRFVCC AN7345(IC302) PB/REC AMP 2. Pin Function Pin No. SymbolI/O Function FunctionI/OSymbol Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 I I 16 17 18 19 20 21 22 23 24I I O I I Playback amplifier output I I I RIN1 OUT1 1. Block diagram Playback amplifier inputR1 R2IPlayback amplifier input NF2Playback amplifier negative feedback OUT2Playback amplifier output EQ2IEqualizer CTL2IPre Amplifier input switching time constant RIN2IRecording amplifier input RNF2IRecording amplifier negative feedback ROUT2 O Recording amplifier outputO LCIALC low cut LPF IALC low pass filter GNDI VccPower supply RFIRipple filter EQCTLEQ control ROUT1ORecording amplifier output RNF1Recording amplifier negative feedback IRecording amplifier input CTL1Pre amplifier input switching control EQ1Equalizer Playback amplifier negative feedback NF1 L2I L1 Playback amplifier input Playback amplifier input Description of major ICs MX-G70 1-33 1 2 8 Vcc 7 OUT2 6 -IN2 5 +IN2 OUT1 1 -IN1 2 +IN1 3 VEE 4 BA15218F-XE (IC652) / BA15218N (IC481,501,502,526,546,571) : Dual op. amp. 1. Pin layout 2. Block diagram Q19 Q17Q16 OTHER CH R9 R6 R8 R7 R5 R4 R3R2 R1 D1 C1 Q18Q13 Q11 Q8 Q5 Vcc VEE OUTPUT -IN +IN Q1 Q3Q4 Q2 C2 Q9 Q6 Q7 Q10 Q12 Q14Q15Q114 MX-G70 1-34 BA3126N(IC301) : R/P Switch R E C S W G 123456789 P / B S W P / B S W G R E C S W C O N T . G N D V c c 123456789 10 GNDOUT1 P1VZIN1IN2VCC1VCC2 P2OUT2 InputOutput Mode IN1IN2OUT1OUT2 Brake0000 1010 0101 1100 CLOCKWISE COUNTER-CLOCKWISE Brake LB1641 (IC851,IC852) : DC motor driver 1. Pin layout 2. Pin function MX-G70 1-35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 BIASC VREFC RPEF NC NC NC CIN AIN VCC SPI-A SPI-B SPI-C SPICSB NC NC TEST AOUT GND Decoupling condenser connection terminal. Decoupling condenser connection terminal. Reference resistance connection terminal. Non connect. Non connect. Non connect. Connected to GND of audio system through a condenser. Inputs the audio signal through a condenser. Power supply terminal. Output selection control terminal. Output selection control terminal. Output selection control terminal. Output selection control terminal. Non connect. Non connect. Connected to GND upon normal use. Multi-plexor output terminal. Connect to GND. - - - - - - - I - O O O O - - - O - No.SymbolI/OFunction 2.Pin Function 1.Block Diagrams BA3835S (IC812) : SPI B.P.F. 1 2 3 4 5 6 7 8 9 18 17 16 15 14 13 12 11 10 BIAS VREF REFERENCE CURRENT MPX A-C RES PEAK HOLD 105Hz BPF RES PEAK HOLD 340Hz BPF RES PEAK HOLD 1kHz BPF RES PEAK HOLD 3.4kHz BPF RES PEAK HOLD 10.5kHz BPF DIF DEC BIASC VREFC RREF N.C. N.C. DIFOUT CIN AIN VCCA B C SEL N.C. N.C. TEST AOUT GND MX-G70 1-36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18Vss DATA CLOCK LCK Q0 Q1 Q2 Q3 Q4 Vdd OE Q11 Q10 Q9 Q8 Q7 Q6 Q5 CONTROL CIRCUIT OUTPUT BUFFER(OPEN DRAIN) 12BIT STRAGE RESISTER 12BIT SHIFT RESISTER 1.Terminal Layout 1 2 3 4 516 17 18 Vss DATA CLOCK LCK Q0Q11 OE Vdd - I I I O I - Connect to GND Serial Data input Shift Clock of Data Latch Clock of Data Parallel Data Output Output Enable Power Supply Pin No.SymbolI/OFunction Latch Data L H OUTPUT ON OFF 2.Pin Function BU2092/F(IC811):PORT EXPANDER MX-G70 1-37 2. Pin Function Pin No. SymbolI/O Function FunctionI/OSymbol Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 FM IN AM MIX FM IF AM IF GND TUNED STEREO VCC FM DET AM SD FM VSM AM VSM MUTE FM/AM MONO/STO I I/O O O I O I I I O O I I III This is an input terminal of FM IF signal. This is an out put terminal for AM mixer. Bypass of FM IF Input of AM IF Signal. This is the device ground terminal. When the set is tuning, this terminal becomes L. Stereo indicator output. Stereo L, Mono: H This is the power supply terminal. FM detect transformer. This is a terminal of AM ceramic filter. Adjust FM SD sensitivity. Adjust AM SD sensitivity. When the signal of IF REQ of IC121( LC72131) appear, the signal of FM/AM IF output. /Muting control input. Change over the FM/AM input. H :FM, L : AM Stereo : H, Mono: L 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 OSC BUFFER AM OSC REG AM RF AFC AM AGC O I O I I I AM Local oscillation Signal output. This is a terminal of AM Local oscillation circuit. Register value between pin 26 and pin28 desides the frequency width of the input signal. AM RF signal input. This is an output terminal of voltage for FM-AFC. This is an AGC voltage input terminal for
