Pioneer-CX680-tape-cdm 电路图 维修手册.pdf

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1、-This Service Manual outlines operations of the CD mechanism module used in the models listed blow. -For repair, use this Service Manual and the Service Manual of the model used in the system. ModelService manualCD mechanism moduleCD mechanism unit DEX-P1R/UC DEH-P946/ESCRT2206CXK5101CXB1699 DEX-P1/

2、ES DEH-P945R/EW CRT2207CXK5101CXB1699 DEX-P99R/EW CX-680 ORDER NO. CRT2216 Service Manual CD MECHANISM MODULE CONTENTS 1. CIRCUIT DESCRIPTIONS . 2 2. MECHANISM DESCRIPTIONS. 15 3. DISASSEMBLY . 17 PIONEER ELECTRONIC CORPORATION 4-1, Meguro 1-Chome, Meguro-ku, Tokyo 153-8654, Japan PIONEER ELECTRONIC

3、S SERVICE INC. P.O.Box 1760, Long Beach, CA 90801-1760 U.S.A. PIONEER ELECTRONIC EUROPE N.V. Haven 1087 Keetberglaan 1, 9120 Melsele, Belgium PIONEER ELECTRONICS ASIACENTRE PTE.LTD. 501 Orchard Road, #10-00, Lane Wheelock Place, Singapore 238880 C PIONEER ELECTRONIC CORPORATION 1998 K-FES. MAY. 1998

4、 Printed in Japan RadioFans.CN 收音机爱 好者资料库 CX-680 2 1. CIRCUIT DESCRIPTIONS 1.1 Preamplifier (UPC2572GS: IC101) Fig. 1 Block Diagram of UPC2572GS Fig. 2 APC Circuit The preamplifier processes pickup output signals to generate signals to be sent to the servo, demodula- tor, and controller. The preampl

5、ifier with built-in photodetector converts signals from the pickup into intermediate voltage in the pickup. Then, addition is made in the RF amplifier (IC101) to obtain RF, FE, TE, and TE zero cross signals. The system consists of the UPC2572GS and other components explained below. The system uses a

6、 single power source (+5 V). There- fore, the reference voltage of IC101 and the reference voltage of the power unit and servo circuit are REFO (+2.5 V). REFO is obtained from REFOUT of servo LSI (IC201: UPD63702GF) via a buffer, and is output from Pin 19 of IC101. This REFO is used as reference for

7、 all measurements. Note: Do NOT short-circuit REFO and GND during measurement. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 X12 RF envelope AGC Detection X3Phase detection3T detection Bottom DC shift Peak Control DC shiftBottom Peak 120k DE

8、FECT circuit FE BAL FE BAL Vcc Mirror circuit FE BAL APC X2 Vcc FE-BAL TE-BAL ASY EFM-OUT C.DEF DEFECT RFOK MIRR 3T-OUT C.FE FE-OUT FE- GND TE- TE-OUT1 TE-OUT2 DET-IN DET-OUT VREF-INVREF-OUT LDON LD PD E F D B C A Vcc C2.3T C1.3T RF- RF-OUT RF-IN C AGC AGC-OUT EFM-IN HPF TE BAL EFM comparator Contro

9、l 1) Automatic Power Control (APC) circuit Laser diode has negative temperature characteristics with great optical output when the diode is driven with constant current. Therefore, current must be controlled by a monitor diode to ensure constant out- put. Thus functions the APC circuit. LD current c

10、an be obtained by measuring the voltage between LD1 and GND. The current value is approximately 35 mA. Vcc (5V) Vr LDMD UPC2572GS 16 PD 17 LD 15 Q101 2SD1664 C124 0.1F C101 (100F/6.3V) R101 10 LD1 R102 12 5V CONT Q102 UMD2N 18 5V 5V 1k 150k 16k R112 2.2k C104 0.33F 5 1k 2.5V Pickup unit RadioFans.CN

11、 收音机爱 好者资料库 CX-680 3 2) RF amplifier and RF AGC amplifier Photodetector outputs (A+C and B+D) are added, am- plified and equalized in IC101, and output to the RFI terminal as RF signal. (Eye pattern can be checked at this terminal.) Low-frequency components of voltage RFI is: RFI = (A + B + C + D) x

12、 3.22 where R111 is offset resistor to keep RFI signal within the output range of the preamplifier. RFI signal is goes under AC coupling, and is input to Pin 4 (RFIN terminal). IC101 contains an RF AGC circuit. RFO output from Pin 2 is maintained to a constant level (1.2 0.2 Vp-p). The RFO signal is

13、 used in the EFM, DFCT, and MIRR circuits. 3) EFM circuit The EFM circuit converts RF signal into digital sig- nals of “0” and “1.” RFO signal after AC coupling is input to Pin 1, and supplied to the EFM circuit. Asymmetry caused during manufacturing of discs cannot be eliminated solely by AC coupli

14、ng. There- fore, the system controls the reference voltage ASY of the EFM comparator by using the fact that proba- bility to generate “0” and “1” is 50% in EFM signal. This reference voltage ASY is generated by output from the EFM comparator through L.P.F. EFM signal is output from Pin 35. As signal

15、 level, amplification is 2.5 Vp-p around REFO. 4) DFCT (defect) circuit DFCT signal detects mirror defect in discs, and is out- put from Pin 33. The system outputs “H” when a mir- ror defect is detected. If disc is soiled, the system determines it as lack of mirror. Therefore, the system inputs the

16、DFCT signal output to the HOLD terminal of servo LSI. Focus and tracking servo drives change to Hold status only when DFCT output is in “H” so that performance of the system upon detection of defect can be im- proved. 5) RFOK circuit The RFOK circuit outputs signal to show the timing of focus closin

17、g servo, as well as the status of focus closing during playback. The signal is output from Pin 32. The system inputs the RFOK signal output to the RFOK terminal of servo LSI. The servo LSI issues Focus Close command. The system outputs signal in “H” during focus closing and playback. CN101 12 7 DETE

18、CT 13 11 10 10k 20k 9.3k RFI +5V R111 27k Vcc 12 ASY 13 20k (RF AGC) AGC RF ENVELOPE HPF VDC RFOK 20k 33 36 35 34 PEAK DEFECT EFM UPC2572GS A+C 10k B+D 9.3k20k 10k 10k R105 6.8k C125 3pF C105 47pF C128 33P R123 10K Q103 2SK303 Q104 UN2111 R104 8.2k RFIN C107 4.7F/35V C122 0.1F C106 RFO REFO (+2.5V)

19、DEFECT BOTTOM R107 8.2k R106 18k C111 3300pF C110 C112 0.047F 654321 32 0.1F 0.01F 1 2 3 SCONT CWX2165 (CXK5121) Fig. 3 RF AMP, RF AGC, EFM, DFCT, RFOK Circuit RadioFans.CN 收音机爱 好者资料库 CX-680 4 7) Tracking-error amplifier Outputs E and F from the photodetector are output as TE signal (E-F) from Pin 2

20、4 via the difference amplifi- er, then via the error amplifier. Low-frequency components of voltage TEY is: TE waveforms equivalent to approximately 1.5 Vp-p are obtained at TE output (Pin 24) by using REFO as reference. The cut-off frequency of the amplifier of the last layer is 19.5 kHz. 8) Tracki

21、ng zero-cross amplifier Tracking zero-cross signal (TEC signal) is generated by amplifying TE waveforms (voltage at Pin 24) by a factor of four. The signal is used for detecting the zero-cross point of tracking error in the servo LSI UPD63702GF. The purposes of detecting the zero- cross point are as

22、 follows: (1) To be used for counting tracks for carriage move and track jump. (2) To be used for detecting the direction of lens movement when tracking is closed. (To be used in the tracking brake circuit mentioned later.) The frequency range of TEC signal is from 500 Hz to 19.5 kHz. Voltage TEC =

23、TE level x 4 In other words, the TEC signal level is calculated as 6 Vp-p. This level exceeds the D range of the operation amplifier, resulting in the signal to clip. However, there shall be no problem, since the servo LSI uses only zero-cross point. 6) Focus-error amplifier The system outputs photo

24、detector output (A+C and B+D) as FE signal (A+C-B-D) from Pin 28 via the dif- ference amplifier, then via the error amplifier. Low-frequency components of voltage FEY is: An S curve equivalent to approximately 1.6 Vp-p is obtained at FE output (Pin 28) by using REFO as refer- ence. The cut-off frequ

25、ency of the amplifier of the last layer is 12.4 kHz. Fig. 4 Focus-error amplifier Fig. 5 Tracking-error amplifier, Tracking zero-cross amplifier CN101 R117 16k R116 16k 14 15 9 11 31k 31k 50pF 63k C123 4.7nF R114 10k R113 10k TBAL C115 120pF R109 68k R115 1k C126 15nF TEY 4R R F E 23 TEC C116 6.8nF

26、TE VCA gm=1/17k 63k 37 24 5pF TOFST R110 130k 50pF 25 REFO (+2.5V) gm CONDUCTANCE UPC2572GS 65 RFO 9.3k 9.3k 20k 10k 10k 7 1312 13 10k 10k 20k FE VCA 38 REFO C114 390pF FE R108 33k 28 FE 27 R 17.2k 50pF gm=1/68.8k 90k 10 11 CN101 A+C B+D F.BAL REFO (+2.5V) gm CONDUCTANCE UPC2572GS 20k90kR108 FEY=(A+

27、CBD)XXX 10k68.8k17.2k : (FE level of pickup unit x 5.02) 63kR109 TEY=(EF) XX 31k+16k17k : (TE level of pickup unit x 5.36) CX-680 5 RFO PEAK HOLD BOTTOM HOLD MIRROR1 A 0 False MIRR caused by dirtTrue MIRR OFF TRACK Dirt, etc. B C Z Fig. 8 3T OUT Circuit Fig.6 MIRR Circuit Fig. 7 MIRR Circuit 9) MIRR

28、 (mirror) circuit MIRR signal shows ON and OFF track information. The signal is output from Pin 31. The status of MIRR signal is as follows: Laser beam ON track: MIRR = “L” Laser beam OFF track: MIRR = “H” The signal is used in the brake circuit mentioned lat- er. 3T-OUT FE signal RFIN UPC2572GS C11

29、3 10nF FEY 3T detection C117 0.033F 120k L.P.FPhase detection 8 + H.P.F 10k 10k 1k C2.3T C109 100pF C1.3T C108 0.027F 8 7 30 29 4AGC Differential rectification 3T LEVEL ENVELOPE DETECTOR Phase comparison 10) 3T OUT circuit The system detects flickering of RF signal when dis- turbance is input to the

30、 focus servo loop, and outputs the difference of phase between FE signal and RF- level fluctuation signal from Pin 30. The resulting sig- nal is obtained through L.P.F. with a fc of 40 Hz. This signal is used for automatic adjustment of FE bias. MIRR COMP DC shift PeakAGC Bottom RFO Detection A 1.5V

31、 UPC2572GS (Peak) (Bottom) 4 31 RFIN B Z C CX-680 6 1.2 Servo (UPD63702AGF: IC201) The servo consists of mainly two parts. The first part is the servo processing unit to equalize error signals and control track jump, carriage move, in focus, etc. The second part is the signal processing unit to per-

32、 form data decoding, error correction, and interpola- tion. The system converts FE and TE signals from analog to digital in IC201, then outputs drive signals of the focus, tracking, and carriage systems via the servo block. The EFM signal input from the preamplifier is decoded by the signal processi

33、ng unit, and eventual- ly output as audio signal after conversion into analog from digital signals via the DA converter (IC201 con- tains audio DAC). Then, the system generates error signal for the spindle servo in the decoding process, sends the signal to the spindle servo to generate drive signal

34、for spindle. After that, drive signals for focus, tracking, carriage, and spindle are amplified in IC301 and BA6797FM, and supplied to respective actuators and motors. 1) Focus servo system The main equalizer of focus servo is located in the UPD63702AGF. Fig. 9 shows block diagram of the fo- cus ser

35、vo. For the focus servo system, the lens must be posi- tioned within the focusing range in order to perform focus closing. To achieve this, the system moves the lens upward/downward by focus-search voltage of triangular waveform to detect the focusing point. During searching, the system kicks the SP

36、DL motor to maintain rotation speed to set speed. The servo LSI monitors FE and RFOK signals so that focus closing is performed automatically at an appro- priate point. Focus closing is performed when the following four conditions are satisfied: (1) When the lens moves nearer to the disc. (2) RFOK =

37、 “H” (3) FZD signal (in IC) is latched to “H.” (4) FE = 0 (REFO as reference) Fig. 9 Focus servo block diagram FOCUS ERROR D/A FD FIN DRIVER FO+ FO IC301 BA6797FM LENS IC 201 UPD63702AGF 76 6420 18 19 16 17 FOCUS SEARCH TRIANGULAR WAVE GENERATOR DAC DIGITAL EQUALIZER CONTROL A/D R302 20k R301 30k CX

38、-680 7 Fig. 10 Sequence of Focus Closing When the conditions mentioned above are satisfied and focus is closed, the XSO terminal changes from “H” to “L.” Then, the microcomputer starts monitor- ing RFOK signal through L.P.F after 40 ms. If the system judges RFOK signal as “L,” the micro- computer ta

39、kes actions, including protection. Fig. 10 shows operations related to focus closing. (The illustration shows when the system cannot per- form focus closing.) S curve, search voltage, and ac- tual lens behavior can be checked by pressing the Focus Close button when “01” is shown in Focus Mode Select

40、 in Test mode. REFO FD LENS POSITION RELATIVE TO DISC NEAR FAR JUST FOCUSED SIN REFO Expanding around Just Focused Point REFO RFI FOK FEX FZD THRESHOLD LEVEL FZD (INTERNAL SIGNAL) Focus closing would normally take place at these points XSO (IN THE EVENT FOCUS IS CLOSED) LEVEL CX-680 8 Fig. 11 Tracki

41、ng servo block diagram Fig. 13 Multi track jump Fig. 12 Single track jump TRACKING ERROR D/A TD TIN DRIVER TO+ TO IC301 BA6797FM LENS IC 201 UPD63702AGF 77 26 27 JUMP PARAMETERS DAC DIGITAL EQUALIZER CONTROL A/D 23 25 24 R304 20k R303 30k 63 t1 t2 GAIN NORMAL TIN KICK BRAKE TEC T. BRAKE EQUALIZER T.

42、 SERVO CLOSED OPEN NORMAL GAIN UP OFF ON t1 TIN TEC (10 TRACK) EQUALIZER T. BRAKE SERVO CIN 2.8mS (4.10 TRACK JUMP) 5.8mS (32 TRACK JUMP) GAIN UP NORMAL ON OFF OPEN CLOSED t2 60mS t 2) Tracking servo system The main equalizer of tracking servo is located in the UPD63702AGF. Fig. 11 shows block diagr

43、am of the tracking servo. a) Track jump Track jump is automatically performed by the auto sequence function in LSI when the LSI accepts com- mand. The system has six types of jump (1, 4, 10, 32, 32x2, and 32x3) for truck jump during searching. In Test mode, the system can select and check these jump

44、 types and CRG move by selecting a mode. The microcomputer sets half of the total number of track jumps (two tracks if the total number of tracks are four), and counts the set number of tracks by using TEC signal. The system outputs brake pulse for a specified time (set by the microcomputer) from th

45、e point of time when the set number is counted, and stops the lens. Thus, tracking is closed, and the sys- tem can continue normal playback. To improve servo withdrawal during track jump, the system sets the brake circuit to ON for 60 ms after brake pulse so that gain of the tracking servo can be in

46、creased. FF/REV in normal mode is made by continuously per- forming single jump approximately ten times faster than in normal playback. CX-680 9 Fig. 14 Tracking Brake Circuit TEC TZC (TEC SQUARED UP ) (INTERNAL SIGNAL ) MIRR MIRR LATCHED AT TZC EDGES = SWITCHING PULSE EQUALIZER OUTPUT (SWITCHED) DR

47、IVE DIRECTION Note: In the illustration, the phase of equalizer output is shown as the same as with that of TEC. FORWARD LENS MOVING FORWARDS (INNER TRACK TO OUTER) LENS MOVING BACKWARDS Time REVERSE b) Brake circuit Servo withdrawal will deteriorate during setting and track jump. Thus, the system u

48、ses the brake circuit to provide stable withdrawal to servo loop. The brake circuit detects the direction of lens move- ment, and outputs only drive signal in the opposite direction from the lens movement. Thus, the system delays the speed of the lens movement to stabilize withdrawal of the tracking

49、 servo. The system judges sliding direction of track from TEC and MIRR signals, as well as the relationship of their phase. CX-680 10 Fig. 16 Carriage Signal Waveforms Fig. 15 Carriage Servo Circuit 3) Carriage servo system Output from low-frequency components (lens posi- tion information) of the tracking equalizer is input to the carriage equalizer by the carriage servo. After obtaining a certain gain, the system outputs drive signal from t