Pioneer-CX977-tape-cdm 电路图 维修手册.pdf

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1、ModelService ManualCD Mechanism Module DEH-P630/X1N/UCCRT2648CXK5500 DEH-P7300R/X1N/EWCRT2649 DEH-P730/X1N/UCCRT2650 DEH-P7350/X1N/ESCRT2651 PIONEER CORPORATION4-1, Meguro 1-Chome, Meguro-ku, Tokyo 153-8654, Japan PIONEER ELECTRONICS SERVICE INC. P.O.Box 1760, Long Beach, CA 90801-1760 U.S.A. PIONEE

2、R EUROPE NV Haven 1087 Keetberglaan 1, 9120 Melsele, Belgium PIONEER ELECTRONICS ASIACENTRE PTE.LTD. 253 Alexandra Road, #04-01, Singapore 159936 C PIONEER CORPORATION 2001 K-ZZA. MAR. 2001 Printed in Japan ORDER NO. CRT2624 CD MECHANISM MODULE CX-977 Service Manual - This service manual describes t

3、he operation of the CD mechanism module incorporated in models listed in the table below. - When performing repairs use this manual together with the specific manual for model under repair. CONTENTS 1. CIRCUIT DESCRIPTIONS.2 2. MECHANISM DESCRIPTIONS.26 3. DISASSEMBLY .28 RadioFans.CN 收音机爱 好者资料库 2 C

4、X-977 1. CIRCUIT DESCRIPTIONS From divisional viewpoint, the CX-977 is roughly divided into four sections, namely, Preamplifier, Servo, Power Supply and Loading Control. This LSI realizes eight types of automatic adjustments (controls) through cooperative work between Preamplifier and Servo unit. Be

5、cause the system uses the single power source (+ 5v) specification, reference voltages used in the servo system (Preamplifier, Servo DSP and Pickup) are all Vref (2.1V). 1.1 PREAMPLIFIER (TA2153FN; IC101) The Preamplifier processes output signals sent from the Pickup and generates signals to supply

6、to each unit of the next stage, that is, Servo, Demodulator or Control. It also performs power control of Pickups laser diode. Signals from the Pickup are I-V-converted by the Preamplifier, which is built-in in Pickups photo detector, and then added-up by the RF amplifier to obtain signals such as R

7、F, FE and TE. Reference voltage, Vref (2.1v), is output from #19 pin of the IC, and 2Vref (4.2v) is supplied to the Servo DSP as the reference voltage to determine its D range of A/D input. Fig. 1: TA2153FN circuit RadioFans.CN 收音机爱 好者资料库 3 CX-977 1) Focus Error Amplifier unit In this sub-unit, outp

8、uts from the photo detector, namely, (A+C) and (B+D), are processed in the differential amplifier and further in the error amplifier, and then, (A+C-B-D) is output as FE signal from #16 pin of IC101 (TA2153FN). Low frequency component of voltage FE is expressed as: FE = (A+C-B-D) x (150k/(51k+1k) x

9、(60k/60k) x (120k/60k) = 5.77 times In FE output, S curve of approximately 1.45 Vpp on the basis of Vref is obtained. The cutoff frequency of the succeeding amplifier is 11.4 kHz. 2) Tracking Error Amplifier unit In this sub-unit, outputs from the photo detector, namely, E and F, are processed in th

10、e differential amplifier and further in the error amplifier, and then, (E-F) is output as TE signal from #14 pin of IC101 (TA2153FN). Low frequency component of voltage TE is expressed as: TE = (E-F) x 300k/100k x 82k/20k = 5.8 times In TE output, TE waveform of approximately 1.51 Vpp on the basis o

11、f Vref is obtained. The cutoff frequency of the succeeding amplifier is 20 kHz. Fig. 2: FE circuit Fig. 3: TE circuit RadioFans.CN 收音机爱 好者资料库 4 CX-977 3) RF Amplifier unit Outputs from the photo detector, namely, (A+C) and (B+D), are added up, amplified and equalized in the Head Amplifier LSI (TA215

12、3FN). The processed-signals are output to RFI terminal as RF signals (These signals are used to check eye patterns). Low frequency component of voltage RFI is expressed as: RFI = (A+B+C+D) x 5.43 RFI is used for RF Offset Control circuit. These RFI signals so output from #28 pin are AC-coupled outsi

13、de the unit, and then re-input to #27 pin and amplified by the RFAGC amplifier to obtain RFO signals. TA2153FN has built-in function for RFAGC adjustment, as described later, and through such function, the gain of RFAGC is controlled so that RFO output stays within 1.2 0.3 Vpp range. Also, RFO signa

14、ls are used for EFM and RFAGC Adjustment circuit. They are further used to generate RFRP and RFCT signals, both of which are used for track counting. 4) RFRP and RFCT Signal Circuit unit RFCT signals are generated through the Head Amplifier (IC101). A RFCT signal is the difference signal that repres

15、ents the difference between the peak and bottom level of RF signal. RFRP and RFCT can be monitored at TP203 (#20 pin of IC101, namely, TA2153FN) and TP204 (#20 pin of IC101) respectively. Size-comparison among TE, RFRP and RFCT signals is performed by the Hysteresis Comparator in IC201 (TC9495F2), a

16、nd through such comparison, track information (TEZC and RFZC signal) is generated. Based on these signals, information to determine tracking speed of the lens when it moves on the disk is generated. Also based on these signals, number of tracks is counted. Fig. 4: RF circuit 5 CX-977 5) SBAD Signal

17、Circuit unit In this unit, outputs from the photo detector, namely, E and F are processed through the addition amplifier. That is, E and F are added together and (E+F) signal is output from #15 pin of IC101 (TA2153FN), as SBAD signal. This SBAD signal, along with Focus Error signal, is used as one o

18、f the conditions that the system uses to internally judge Focus ON/OFF based on them. Also, SBAD signal is used to detect defects: defects that may be detected when the Pickup passes a scratch on the disk, for instance. Fig. 5: RFRP and RFCT circuit Fig. 6: SBAD circuit 6 CX-977 6) APC Circuit unit

19、If a laser diode is driven at constant current, its optical output comes to have high level negative-characteristics, and this may cause it out-of-control drive because of the heat. So, driving current must be controlled, through use of a monitoring diode, so that optical output remains within the s

20、pecific degree. This is exactly where APC circuit works. LD current can be obtained by measuring the voltage between LD1 and GND. The value is approximately 35 mA at room temperature. Fig. 7: APC circuit 7 CX-977 1.2 SERVO DSP (TC9495F2; IC201) 1) Focus Servo system The main equalizer of the Trackin

21、g Servo is comprised with a digital equalizer unit. Fig. 8 shows the block diagram of the Tracking Servo. Fig. 8: Block diagram of Focus Servo circuit 8 CX-977 A series of actions of detecting in-focus point and switching on the Focus Servo upon such detection are called focus search. In Focus Servo

22、 system, the system needs to move the lens to in-focus point so that it performs Focus Close. So, the system detects in-focus point moving the lens up and down, which it performs by changing focus search voltage of a triangle wave. During these operations, the spindle motor maintains offset mode and

23、 keeps constant rotating speed. The Focus Servo is switched on through three steps shown below. 1. FOK=H 2. The Focus Error signal exceeds Focus Standby level threshold 3. The Focus Error signal reaches Zero Cross Here are descriptions of the three steps. While there is enough distance between the l

24、ens and the in-focus point, the system cancels SBAD offset, and defines this level (distance) as SBOFF. Then, starting from this SBOFF standard, SBAD level moves toward FOK threshold, reaches it, and finally exceeds the threshold. Upon this passing over the threshold, the condition of the lens becom

25、es FOK =H. As the lens moves up and down, the focus error signal changes at the in-focus point. CD-LSI (IC201) analog/digital- converts such signal, and then, let the signal pass through the high-pass filter to remove the offset component of the signal. The signal so processed is called FEHPF signal

26、. When the level of the FEHPF signal (internal signal of the LSI) exceeds Focus Standby level, because it means the lens has come to close to the in-focus point, the system sets the condition of the lens to Servo-ON Standby. Finally, the FEHPF signal matches the value of the in-focus point, and the

27、system triggers ON of the Focus Servo. 9 CX-977 The microcomputer monitors FOON signal while the system is performing focus search, and starts monitoring of FOK signal from the point when 40 ms has passed after FOON signal became active (The signal is active when the condition is Servo ON. It shows

28、L in a test with a probe). If the microcomputer judges that FOK is not active, it performs necessary actions such as protection. When, under Test mode, you press the Focus Close button, with the Mode Select of the focus set to Display 01, you can check Focus Error signals, search-voltage and actual

29、actions of the lens. Fig. 9: Focus Search Timing 10 CX-977 2) Tracking Servo system The main equalizer of the Tracking Servo is comprised with a digital equalizer unit. Fig. 10 shows the block diagram of the Tracking Servo. Track jump Track jump is automatically performed with a command issued by th

30、e microcomputer. It is performed through Auto- Sequence function that the LSI has in it. The CX-977 has two types of track jump as those used for searching. Namely, the Lens Kick mode used for 1, 4, 10, 32 and 100 track, and the Carriage Move mode used for jumping of more than 1,000 tracks. Under Te

31、st mode, you can use, to check the track position, 1, 32 and 100 jump as Lens Kick jump and Carriage Move jump according to mode selection. Lens Kick jump A Lens Kick jump is performed when the LSI receives a Lens Kick command from the microcomputer. Direction of jump and number of tracks are specif

32、ied by the command. When the LSI receives a Lens Kick command, it applies kick pulses to the tracking EQ, and the jump occurs. The LSI controls travelling speed of the lens by referring to the table it holds in it. In such way, the lens travels faster when there are a good number of tracks to go, wh

33、ile travelling speed gets slower as the number of remaining tracks decreases. When track count is completed, Tracking Close is performed. During jump, the LSI observes RFRP signals, and based on the signals, performs track count. It detects the direction of the jump based on phases of RFRP and TEZI

34、signals. To prepare for good servo-feed in next time track jump, the system performs operations to increase Tracking Servos gain and hysteresis operations for 50 ms after completion of Tracking Close. The system realizes FF/REV actions under Normal mode by continuously performing single jumps. The s

35、peed of FF/REV is approximately 10 to 20 times faster than Play (varies depending on the direction). Fig. 10: Block diagram of the Tracking Servo 11 CX-977 Fig. 11: Lens Kick 12 CX-977 Carriage Move jump A Carriage Move jump is performed when the LSI receives a Carriage Move command from the microco

36、mputer. Direction of move and number of tracks are specified by the command. When the LSI receives a Carriage Move command, it makes the Tracking Servo Open, applies kick signals to the Carriage EQ and make the carriage motor drive. Thus, a track jump occurs. The profile of the kick signals so appli

37、ed to the EQ has the specific constant given to it at the starting-up of the jump operations. So, as the number of remaining tracks decreases, voltage is lowered so that travelling speed of the carriage becomes slower. In this way, by reducing speed just before the jump terminates, the servo-feed at

38、 the end of the jump is improved. Also, to prepare for good servo-feed in next time track jump, every time a jump is completed, the system performs operations to increase the gain of the Tracking Servo and hysteresis operations for 60 ms after the completion of the jump. Fig. 12: Carriage Move 13 CX

39、-977 Hysteresis operations In certain operation, such as Setup or jump, servo-feed tends to be deteriorated during operations. Hysteresis is the operation to keep stable feed to servo-loop under such conditions. It acts in such manner that it holds a TE signal when each beam spot comes to off-track

40、position, so that convergence of the Tracking Servo can be improved. Fig. 13: Hysteresis operations 14 CX-977 3) Carriage Servo system The Carriage Servo inputs low-frequency-component output (lens position information) of the tracking equalizer into the carriage equalizer, then, after it has earned

41、 certain amount of gain, it outputs a drive signals from the LSI. Further, such drive signals are applied to the carriage motor via the driver. Specifically, the system works as follows. That is, entire body of the pickup needs to move to the forward direction when the lens offset reaches certain le

42、vel during Play. So, the gain of the equalizer is set in such manner that the equalizer constantly outputs higher voltage than the starting-up voltage of the carriage motor when such condition occurs. Practically, the system satisfies such requirement in such manner that the Servo LSI outputs the dr

43、ive voltage only when the equalizers output exceeds the specific level of threshold. To minimize power consumption, and to stabilize operations, the level of threshold is pre-set slightly higher than the starting-up voltage of the motor. Waveforms of output of this drive voltage take pulse shape. Fi

44、g. 14: Block diagram of Carriage Servo circuit 15 CX-977 4) Spindle Servo system Fig.16 shows the block diagram of the Spindle Servo. Fig. 16: Block diagram of the Spindle Servo circuit Fig. 15: Carriage signal waveform 16 CX-977 Spindle Servo has the following modes CLV Servo mode This is the mode

45、the system uses for such span as after Focus Close and before it applies brake to the motor to stop the disk. Before Tracking Close and during normal Play, the system operates under this mode. During this mode, the system performs synchronous detection in EFM demodulation block in the CD-LSI (IC201)

46、 so that the disk keeps predefined rotating speed. To realize synchronous detection before Tracking Close the system adopts such method that it applies to PLL circuit the same speed control by VCO that is performed in the LSI. On the other hand, as to speed control after Tracking Close, control by V

47、CO is muted and the method is switched to speed/phase control through the master clock (a ceramic oscillator). Offset Servo mode (a) After the kick is over in the setup, this mode is turned on until changing to rough servo mode. (b) When focus is lost during play, this mode is turned on until the fo

48、cus is restored. Both of the above are used for maintaining the disc rotation rate near to the specified rate. Brake mode The mode is for use to stop the spindle motor. Brake Sequence starts up when the microcomputer sends the command to CD-LSI. Then, the LSI, watching disks rotating speed, sets the

49、 flag when it detects that the speed comes to approximately one twentieth (1/20). On the other hand, the microcomputer, also monitoring such flag, switches off the servo when it caches the flag. In case the microcomputer cannot catch such flag within the specific period after starting-up of the Brake Sequence, it changes the mode to Stop, and monitoring FG pulses, keep the mode until it confirms that the spe