User manual SONY CDP-291 service manual

[. . . ] These 200 series models are mechanically complex so there are more CD transport and mechanical adjustments to be made. The concepts and circuitry in this 200 disc model are similar to the 300 disc CDP-CX300 series and 400 disc CDP-291 series CD Changers. In these larger capacity models, the CD transport and CD mechanism use fewer parts. Generally, the electrical troubleshooting procedures and test modes outlined in this training manual can be applied to all of the changer models listed for the last three years. [. . . ] As current flows through the focus coil, the lens is moved either toward or away from the disc depending upon the direction of the current. Therefore, applying sufficient current to this coil will move the lens and its focus point to the disc's information layer. Tracking Coil The tracking coil on the objective lens is perpendicular to the focus coil. Current through this coil moves the lens and the laser beam to one side or another. This movement keeps the laser beam on the spiral track as the disc rotates. When the tracking coil has moved the lens to the limit, the sled moves the optical assembly to follow the spiral track. This re-centers the lens within limits and the tracking coil can continue to follow the track once again. FOCAL POINT CD LASER BEAM LENS TRACKING COIL TRACKING ERROR SIGNAL FOCUS COIL LASER BEAM FOCUS ERROR SIGNAL (FE) PD LD LASER CONTROL A-D, E, F DETECTOR OUTPUT OPTICAL PICKUP 7A122 1245 7/7/00 30 31 Servo / Audio Processing Block In order for the CD player to produce audio, the servo section must control the laser beam so it can recover the digital data from the disc. Once the data is stable and output at a constant rate, it can be processed and returned to analog audio. Sled Motor When the CD Changer is turned ON (no disc chucked), the tray table rotates to determine its position. Within the CD mechanism, the sled motor drives the optical assembly toward the spindle motor until the limit switch is closed. If this switch doesn't close, the laser and focus search will not take place and the CD will not spin. Servo Block A chain of events must occur for the laser to read the disc's data. The sequence is as follows: Servo Control Driver M 5V Limit switch S101 Operation 1. Focus search / servo ON CD Play Sequence Purpose Begins reading the CD at the TOC area To read the disc data Find and maintain focus on the disc Check Sled moves the block toward spindle motor at Power ON Laser power meter Scope at the FOK test point. Servo control amplifies the TE input and closes the servo loop switch, outputting the amplified tracking error signal (TEO). Servo Control TEO RFO, FE TE test point TE Driver Optical Assembly Lock Spindle Servo Control LPF Driver M FE RFO RF Amp A-D detectors Optical Assembly E, F Audio Block RF Amp The driver IC that receives TEO supplies current to generate a magnetic field in the tracking coil. The coil moves the objective lens (with laser beam) so the beam follows (tracks) the disc data. Once the spindle motor is locked to the data (LOCK = HIGH), the data is reliable enough to be audio processed. It is error corrected, digitally reconstructed and output as a digital signal to the rear panel jack. The digital signal is also converted to analog within Servo Control and delivered to the rear panel L & R jacks. While audio is output, the front panel display is receiving the CD track and playback time information. Servo Control sends Sub Q digital data (and clock) to Syscon for compiling and interpreting. The resultant information is sent to the FL Display Driver as Data, Clock and Latch signals. The Display driver determines what display segments of the tube have to be lit to produce the desired time and track characters. OPTICAL PICKUP ASSEMBLY A-F RF AMP FE TE RF 0 (EYE PATTERN) ANALOG AUDIO OUT FOK LOCK C2PO DIGITAL OUT DISPLAY TUBE PLATE, GRIDS FL DISPLAY DRIVER COIL/MOTOR DRIVE SERVO CONTROL/ DIG SIGNAL PROCESS (DSP) DATA CLK CD DATA (SUB Q) LOADING SW. S101 (OPTICS AT HOME POSITION) SYSCON DATA CLOCK, LATCH SERVO/AUDIO PROCESS BLOCK 9A122 1251 6/29/00 34 35 Servo Processing There are several main servos that can be tested for normal operation. Focus The focus search operation is also initiated when the disc is chucked in the CD Mechanism (S801 not shown) and the limit switch (S101) is closed. Servo Control IC101 generates the electrical signal that results in the visible lens movement in the optical assembly. The changeover from search to servo lock occurs when RFO signal is present and the FE "S curve" shaped signal voltage crosses to/through Vc voltage (half of Vcc. [. . . ] 1. 2Vp-p Time base = 0. 5msec/div. RFO when the tracking servo is open (defective). 1. 3Vp-p 1msec/div. Normal RFO in-between songs 1. 2Vp-p Time base = 0. 5usec/div. RFO when the spindle motor is bad. The motor's worn bushing causes vibration that upsets the tracking servo. This causes the scalloping along the bottom of the waveform vi Abbreviations Used In Compact Disc Player ###FS APC ASY ATSC ATTM BCK BW C16M C1F1 C1F2 C21O C2F1 C2F2 C2FL C2PO C4LR C4M C864 CLTV CLV Automatic Tracking Sensitivity Control ATTenuate Bit ClocK BandWidth Clock 16 MHz Corrector 1 Flag 1 Corrector 1 Flag 2 Clock 2. 1 MHz Output Corrector 2 Flag 1 Corrector 2 Flag 2 Corrector 2 FLag out Corrector 2 Pointer Out Clock 4x Left Right Clock Clock 4 MHz Clock 8. 64 MHz Control Loop Timing Voltage Constant Linear Velocity Clock ÷ or x of Sample Frequency Automatic Power Control ASYmmetry Control Signal A division or multiple of a clock or sample frequency. [. . . ]