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B225
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1. 1-1 1*1* 1 1*1*2 1*1*3 GENERAL Index of CO olayer controls General controls Special controls Rear panel connectors
page
1/i 1/1 1/2 1/3
2. 2.1 2*2 2.3 2*4 2®5 2*6 2*7 2*8 Z«9
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REMOVAL OF ASSEHBLIES Removing Removing Removing Removing Removing Removing Removing Removing Removing the tne the the the the the tne the top cover side panels individual circuit boards player mechanism display po^er t r ansf or mator drawer motor operating panel guide rods 2/1 2/1 2/1 2/1 2/2 2/2 2/1 2/3 2/3
3* 3.1 3.1®1 3*1*2 3*1.3 3*1*4 3.2 3.2*1 3^2*2 3*3 3.3^1 3*3.2 3*3*3 3«3r-4 3.3.5 3*4 3.4.1 3*4^2 3«4*3 3.5 3* t · 1 > 3»5«2 3. 5. J 3*o 3.t».l 3*6.2
CIRCUIT
DESCRIPTIONS 3/1 3/1 3/1 3/2 3/2 3/3 3/3 3/4 3/4 3/4 3/4 3/5 3/5 3/6 3/6 3/6 3/6 3/6 3/6 3/7 3/7 3/7 3/7 3/7 3/3
SERVO 1 PC3 1.759.310 Stabilization of the supply voltages Orawer position detector Focus control loop Oisc motor control loop Microprocessor PC3 . 1.769.320 Microprocessor system Drawer motor control SERVO- 2 PCP 1.769*330 Radial control Radial control circuit Automatic gain control- {AGC-} circuit Offset control circuit. Track detecting circuit Preamplifier and laser PCB 1*769*100*35 Laser control Focus and radial control signals HF signal amplifier Decoder PCh l-7o^.300 D i g i t a l signal p r o c e s s i n g Digital sine-wave generator HFL and 0 J detector OAC TC3 1.769.23 3 digital filtering (oversampl ing) and 0/A conversion Level adjustment and headphones amplifier
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*· 4 i 4«-l»l 4.1.2 4.1.3 4.1.4 4.1.5 4®2 4.2.1 4.2.2 4*2®3 4.2.4 4«Z*5 4*2*6 4*»2#7 4.3 4*3.1 4*3#2 4.3.3 4.3*4 4.3.5 4.3.6 4.3.7 4.3.3 4.4
TEST POINTSt ADJUSTMENTS
OH E225 4/1 4/1 4/3 4/4 4/6 4/8 4/9 4/9 4/9 4/9 4/9 4/10 4/10 4/11 4/11 4/i1 4/11 4/11 4/11 4/12 4/12 4/12 4/12 4/12
Test points on 622^ Test points on SERVO I PCB 1«?69*310 Test points on SERVO 2 PCB 1.769.330 Test points on microprocessor PCB 1.769*320 Test points on decoder PCB 1.769.300 Test points on 0AC- PCB 1.769.260 Adjustments on CO player B225 Aids Aligning the player mechanism? general Adjusting the laser current Adjusting the balance Adjusting the focus gain Checking the -tingle alignment Adjusting the DC component of the focus signal Measuring the audi.o data A i 4s Harmonic distortion Output level Frequency response Cross talk Signal-to-noise ratio* linear Signal-to-noise ratio? weighted Phase linearity Listening test with reference CO
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5*
DIAGRAMS
6.
SPARE PARTS
7* 7.1 7«Z
TECHNICAL APPENDIX Technical data Dimensions 7/1 7/2"
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1. 1.1
GENERAL
I n d e x of CD p l a y e r
controls
1.1.1
General
controls
1 Ij POWER *
Key for switching the CD player ON and OFF. However, certain assemblies (such as the IR receiver) remain always switched" on (in so-called standby m o d e ) . The drawer with the player mechanism [ 2 j LOAD [6j opens or closes when this key is pressed. [ 3 J STOP * Interrupts the player function. The optical laser head is retracted to the starting position and the program is cancelled if the CD player was in program m o d e . The position in which the laser pickup was operating before STOP was pressed cannot be reproduced. If this is desired, please refer to tJL (PAUSE) key. [ 4 J PLAY/NEXT Play key with the following functions; If pressed after LOAD [ 2 j , the CD starts to rotate, the content list is read, and the disc is played starting at the first selection (TRACK). The next selection (TRACK) is accessed when this key is pressed again. If pressed after PROGRAM MODE [26 J has been selected: play program mode is activated. H5"f REPEAT The selection currf.r^ly being played is repeated immediately when this key is pressed. If the CD player is in STOP m o d e , the first selection of the compact disc will be played. If the CD player is in program mode, the current program step will be repeated. [6j (CD drive) Drawer module with CD player mechanism and liquid-crystal display. The drawer can be opened or closed with LOAD [ 2 ] . [7j (Display) Multifunction LC display 'which provides information on all operating modes of the CD player and the content of the loaded compact disc. [8j (keys 0-9) Digit keys for direct addressing of a selection (TRACK) in conjunction with PLAY/NEXT [ 4 j , or for programming.
The CD player can be switched on by pressing any of the controls [ Ij through [8j of the upper row (except REPEAT [5j and the digit key 0 ) . The CD player starts in the selected operating mode.
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1.1.2
Special controls
The controls in the lower front-panel section can be roughly divided into two function groups: controls for supplementary player functions, and programming controls. A Controls for supplementary player [9] PHONES [10] VOLUME + [11j VOLUME [12] CAL TONE * functions
13] AUTOSTOP
[ 14j Key · [ 1 5 J VA (pause ) * [16] « key [17] DISPLAY
Headphones jaGk socket for headphones 200 to 600 ohms. Increases the headphones level and the level of the VARIABLE OUTPUT. Decreases the headphones level and the level of the VARIABLE OUTPUT This calibration button connects a 1000 Hz calibration tone to the outputs so that the recording level of a connected tape deck can be accurately adjusted. The 1000 Hz CAL TONE corresponds to the maximum output level. This maximum level is system-dependent and will not be exceeded even by short peak pulses. Interrupts the playing sequence at the end of the current selection or program step. The laser pickup is automatically positioned at the beginning of the next selection. The next selection is started immediately when PAUSE TA [15] is pressed. Upon conclusion of this selection, the CD player switches again to PAUSE mode. Repositions the pickup from any location toward the end. Interrupts the playing sequence at any time. Repositions the pickup from any location toward the start. Switches over the display mode. The time elapsed since the start of the current selection is displayed in normal PLAY mode. The total play time from the start to the current selection can be displayed by pressing this key.
These functions can also be programmed. PROGRAMMING keys 18] LOOP * Command key for repeating the CD or the proqr^4«until STOP [3j is pressed. Forward "paging" in program mode. Particularly useful for modifying an existing program. Same function as [19] but backward paging. Infrared receiver window Memory load key to be pressed after each program step entry. The next program step is subsequently displayed so that the corresponding entries can be made. Allows a start and a stop mark to be set in programming mode while a selection is being played. Any CD location can thus be programmed. Switches the display in programming mode from selection (track) input to time input (minutes and seconds).
19] +
[20] [21] IR SENSOR [ 22] STORE
[ 23] MARK
[24] TRACK/TIME
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[25j CURSOR
[26 J PROGRAM
Any position on the display can be edited by approaching it with the cursor. NOTE; if the display is in TIME mode, the cursor must be advanced with this key in order to enter the seconds after the minutes. Sets the program entry mode. If PLAY/NEXT [4J is pressed after the program entries have been completed, the CD player starts in PROGRAM mode, If the CD player is to be started in normal mode after the program entries have been completed, press the PROGRAM key [ 26 J again before PLAY/NEXT [4].
1.1.3 [30]
Rear-panel connectors AUDIO OUTPUT FIXED. Output for connecting an amplifier on which the input can be matched to the level of the CD player (the REVOX B251 amplifier is ideally matched at the factory). AUDIO OUTPUT VARIABLE. Active speakers or an output stagef etc. can be connected directly to this output. The volume can be adjusted with VOLUME + and - on the front panel of the CD player. AC POWER. Power inlet (the setting of the line voltage selector can be checked adjacent to it ) . · " REMOTE. This connector can be used for: a) disabling the IR receiver and b) connecting a cable-type remote control device.
[31]
[32] ..[33J
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SECTION 2/1
2.
REMOVAL OF ASSEMBLIES
Important: Disconnect the CD player from the AC supply before removing any parts of the housing.. For certain work it is necessary to open or close the drawer module. This can be done manually without damaging the unit. 2.1 Removing the top cover
- Unfasten five screws [Aj on the rear of the CD player. - Withdraw cover toward the rear.
2.2
Removing the side panels
- Unfasten two screws on each side panel in order to remove them. 2. 3 Removing the individual circuit boards
The circuit boards are accessible when the top cover is removed (Section 2.1). The circuit boards 1.769.280 (DAC PCB), 1.769.300 (DECODER PCB), and 1.769.330 (SERVO 2 PCB) can be pulled out of the interconnection board after the fixing screws [ B] have been unfastened. Four connectors must be detached before the PCB 1.769.320 (MICROPROCESSOR) is removed. Then unfasten screw [Bj and withdraw the PCB from the housing toward the rear. The SERVO 1 PCB 1.769.310 is connected to the chassis via the cooling plate of the voltage regulators. First detach all connectors leading to this PCB. Push the drawer out completely in order to gain access to the three fixing screws. The three screws [C] can subsequently be unfastened and the PCB withdrawn toward the rear . 2. 4 Removing the player mechanism.
- Remove top cover (Section 2.1) - Push drawer out part of the way and set the CD player upside down. - Now pull the drawer out to the point where the screws [ Dj ^become accessible. - Unfasten screw [Dj and set the CD player again in its - . ~ normal operating position on thefc--^ch(NOTE; hold the player mechanism with your hand to prevent it from falling out of the drawer). - Pull drawer out completely and carefully lift the CD player.
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SECTION 2/2
Detach the six connectors (see Fig. 2.5). The player mechanism can now be lifted out of the drawer»
2.5
Removing the display
- Open the drawer and unfasten two screws [ Ej on each side. - Unfasten cable clamp [F] and detach connector of cable harness. The display can now be lifted out by carefully sliding the cable harness out below the player mechanism.
2
·6
Removing the power transformer
- Remove top cover (see Section 2.1). · - JJniiasten four screws [Gj from the bottom. - Detach the connectors of the power transformer to the SERVO 1 PCB 1.769.310, remove power inlet by unfastening the two screws and unfasten screw [Hj (black cable, soldering tag). - The transformer can now be removed. 2.7 Removing the drawer motor
- Remove top cover (see Section 2.1). - Remove power transformer (see Section 2.6). - Unfasten three screws [Hj from the top, unhook spring [I], detach connectors leading from the motor to the microprocessor PCB 1.769.320, and carefully lift out the motor.
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2.8
Removing the operating panel
- Remove top cover (Section 2.1) and side panels (Section 2.2). - Unfasten four screws [Kj each on the top and the bottom of the operating panel.
Carefully withdraw operating panel' from the chassis and detach the connectors.
2
-9
Removing the guide rods
- Remove top cover (see Section 2.1). - Unfasten the inner retaining ring [Lj; the rod can now be pulled out of the unit from the rear. Note: Do not lose the small O-ring that cushions the drawer stop2.10 Reassembly The CD player is reassembled by following the dismantling steps in the reverse order. It is absolutely essential to secure the cable harness in the drawer with a clip as illustrated in Fig. 2.7.
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SECTION 3/1
3. 3.1
CIRCUIT
DESCRIPTIONS
SERVO 1 PCB 1.769.310
The following circuits are implemented on the SERVO 1 PCB; - Stabilization of the supply voltages - Drawer position detector - Focus control loop - Disc motor control loop 3.1.1 Stabilization of the supply voltages
All supply voltages are stabilized by voltage controllers (IC 4 to IC 9, LM317/LM337). The +5V supply (+5 V STBY) is always available. It supplies the microprocessor system and the IR receiver even when the CD player is switched off (standby). The remaining supply voltages are switched on or off by the microprocessor with the PS-OFF signal. When the CD player is switched off, PS-OFF becomes "H" (+5 V) and transistors Q9 and Q10 become conductive (staturated), causing the +5 V and +12 V supply voltages to drop to a residual voltage of 1.3 V. The -7 V supply is switched off through the circuit R 3 8 , R39 ? and Q8; the -12 V supply via R52, R 5 4 , and Qll; and the -17 V supply via R 5 1 , R53 f and Q 1 2 . This prevents the positive supply voltages from becoming negative. The voltage is doubled through diodes D 1 5 , D16, D17 and capacitors C 2 9 , C30 # and taken to the voltage controller IC9 for the -17 V supply. D18 protects the controller from an excessive direct-axis component of the voltage.
3.1.2 Drawer position detector The two light barriers DLQ1 and DLQ2 (on PCB 1.769.310) check whether the drawer is open or closed. The corresponding signals indicate the following conditions:
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SECTION 3/2
3.1.3 Focus control loop The lens can be moved vertically and is designed similar to the mechanical system of a speaker. The lens is controlled magnetically. The coil is stationary and the magnet moves. The focus error signal FOC-ERR is first amplified (lead amplifier IC2a, R3, R12, R16, R17, C3, C4) and subsequently taken to the controlling amplifier ("lag" amplifier Rl, R2, R5, Rll, R15, R29, R30, C2, C12, IC2b, Q6, Q7 and the impedance of the lens coil). In STOP mode, the control loop is interrupted via Ql by the signal FOC-0 {= H) which means that no unnecessary power is consumed by the output-amplifier (Q6 and Ql).
The start-up circuit (IC1, R6, R7 ) adjusts the focussing to the reflective layer of the compact disc. The signals FC-1 and FC-2 are alternatingiy switched to "H", causing the lens to move alternatingiy up or down. Once the correct focus has been found, the signal FOC-NEG briefly drops to "L". The microprocessor then enables the focus control loop (FOC-0, FC-1, and FC-2 - "L" ).. Up to 12,000 tracks per second are skipped in fast search mode. Because the focussing lens readjusts for each track, a whistling sound of approximately 12 kHz would develop as is the case with a speaker. This whistling sound is eliminated by R60, R61, C31, Q13 in the control loop. This filter is only active in search mode.
3.1.4 Disc motor control loop The data from the compact disc must be supplied as steadily as possible to the digital signal processing c i r c u i t . The speed with which these data (bits) arrive depends on the position of the laser pick-up (constant peripheral speed between 1.2 and 1.4 m / s ) . If the laser pick-up reads in the middle of the CD, the^speed is-much higher than near the edge. The speed correction signal MCES is generated in the error correction Ic"(SAA 7020 on PCB 1.769.300). The signal MCES is switched off or on via the signal FOC-0 (R15, R16, IC3b on PCB 1.769.330). The signal is first filtered via a 2nd order low pass (R22, R23, R 2 5 r R26, R28, C10, Cll, I C 3 b ) . The "lead network" is formed by C9,R19, R21, R 2 4 , and R 2 8 , the ,rlag network" by IC3a, C6, C7 , R8 , Q 2 , and Q 3 . As soon as the focal point has been found, the signal FOC-0 changes to "LOW1' and the signal MCES is enabled. A negative pulse via C5 is simultaneously triggered on IC3a, pin 3, thereby fully driving transistor Q3 in order to rapidly accelerate the compact disc. The speed is subsequently controlled by the MCES signal.
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SECTION 3/3
3.2
Microprocessor PCB 1.769.320
The microprocessor system and the drawer control are implemented on the microprocessor PCB 1.769=320. 3.2.1 Microprocessor system
The master microprocessor (M-jiP, IC2 ) scans the keyboard (POO to P G 5 , P10 to P 1 4 ) . The microprocessor system is reset when the LOAD key is pressed. To enable differentiation between a power failure and a LOAD command, P15 of the master processor is also pulled to "LfI in conjunction with a LOAD command. Capacitor C12 latches this condition until P15 is read. This unconventional circuit arrangement offers the advantage that a RESET command can be initiated at any time by pressing the LOAD key in the event that the system becomes blocked for any reason. The commands from the IR receiver or the REMOTE socket are read through the interrupt input of the master processor . When a command arrives from the IR remote control, the IR-REC signal is switched to "LOW" for approximately one second, causing the LED in the IR receiver window to turn on (command acknowledgment). The signals B R A ^ T O S 3 ! and DRA-POS-F supply the processor with drawer position information. The signals CLK, DATA, DLEN-1, and DLEN-2 control the two LCD drivers PCE 2111 (on PCB 1.769.250). The gain of the headphones amplifier and the VARIABLE OUTPUT is controlled by the signals CLK, DATA, and DLEN-3 (on PCB 1.769.280). The slave microprocessor (S-]iP, IC4 ) processes the subcode (supplementary information on the compact disk such as track, time, e t c . ) . The required signals originate from PCB 1.769.300 (IC13, SAA 7010, signals Q-SYNC, SWCLK, Q-DATA, and P - B I T ) . The-signals RC-0 and RC-0 switch the radial-control loop on or o f f . When the radial control loop is switched off (RC-0 = L ) , the laser pick-up can be repositioned with the signals RCl, RC2, CUR-SUM, and CUR-DIR. The track signal (TRK) is read through the interrupt input of the slave processor. This signal changes to " L " as soon as the laser pick-up passes over a track. The direction in which the laser pick-up moves is reported to the slave processor by the signal Tl. This signal also changes to "L" as soon as the laser pick-up passes over a track. It is also used in search mode for counting the tracks. Because the counting speed of the microprocessor is not high enough, only every other track is counted in fast search mode (division by 2, I C 6 b ) . Any program entered through the keyboard Is stored serially ,in.IC5 (serial R A M ) . Both microprocessors are initialized by IC1 (reset chip TL 7 7 0 5 ) . The +5 V STBY supply is supervised by ICl via pin 7. A reset is also ' initialwai via R l / R 8 , and C8 when the LOAD key is pressed. Commands from a cable-type remote control can be read through the REMOTE socket (pin 2 and pin 3 ) . These commands are electrically isolated through the optocoupier IC 12a. These signals are converted to TTL signals by the comparator circuit (IC9a, R 4 4 , R45, R 4 8 , and R 6 0 ) . In order to disable the commands from the infrared receiver, the voltage at pin 4 must be higher than on pin 2 by +5 V. The +5 V STBY of the REMOTE socket can be used for this purpose (interconnect pins 1 and 2, pins 4 and 5 ) . The IR signal is thus shortcircuited via DLQ2, R41, R42, R43, R 6 2 , and IC9b.
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SECTION 3/4
3.2.2
Drawer motor
control
The drawer motor amplifier (IClOa, R 5 2 , 5 3 , 5 6 , 57, and R 5 8 , C 1 4 , Q8 and Q9) is controlled through the shift register IC3 (pins 4 and 5 ) . If the drawer movement is blocked during the opening or closing operation, the motor current rises and hence the voltage across R 6 4 . Signal Tl of the master processor consequently changes'to "L" (circuit R40,54,55,59,63, Q 6 , ^ Q 7 , C 1 3 , and I C l O b ) . In response the master processor reverses the direction of the drawer movement. 3.3 SERVO-2 PCB 1.769.330 for
The SERVO 2 PCB 1.769.330 contains the circuits radial control and the IR receiver. 3.3.1 Radial control
A moving arm allows the laser pick-up to follow the track horizontally. This arm basically functions like a moving coil instrument. The radial-control circuit can be subdivided into four blocks: - Radial control circuit - AGC circuit - Offset control circuit - Track detection circuit 3.-3.2 Radial-control circuit
The value of the radial-error signal can be computed as follows^ RE= kd (II + 1 2 + 1 3 +14) - k (II + 1 2 ) . The value of k is determined by the AGC circuit, and d by the offset control circuit. RAD-ERR2 = 1 1 + 1 2 RAD-ERR1 = 1 3 + 1 4 The signals RAD-ERR1 and RAD-ERR2 are summed via the circuit IC9b, R58/59/61/62/63 and Q6. The sum flows as a current through R63 and Q6. The error signal RAD-ERR 2 is converted via R55 and R57 to a current that flows through R54 and transistor E of IC8. The factor k is formed by transistors A and B as well as C and D (IC8), factor d is formed by Q5 and transistor F (IC8). The signal RAD-ERR 2 x k (=k [II + 12]) on pin 10 of IC9c appears on pin 9 of IC9c; the signal [RAD-ERR1 + RAD-ERR2J kd (= kd [11 + 12 + 13 + 14j) appears on pin 10 of IC9c. The difference signal (RE), developed in IC9c, appears on Pin 8 (RE = kd [II + 12 + 13 + 14 j - K[I1 + K2j ) . The "lag" network of the radial control is implemented by R66, R 6 7 , R68, C15, and IC9d, the "lead" network by R69, R7 0, and C16. The signal is conducted to IC5 through the protective diodes D5 and D 6 . The signal is^taken through switch B (IC5) to pin 2 of IC2 which together with Q 2 , Q 3 ; R 6 , R7", R 8 , R T 1 , and C5 constitutes the_output stage for the radial-control signal RAD-MOT+/ -RAD-MOT-. RT1 protects the coil;- ThJBMwontrol can be disabled (Signal R C - o ) . This occurs in search, p a u s e , forward and reverse mode. The laser pick-up can be positioned during this phase with the signals R C - 1 , R C - 2 , CUR-DIR, and CUR-SUM.
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SECTION 3/5
3.3.3 Automatic gain control (AGC) circuit The bandwidth of the radial-control circuit is stabilized by this circuit. A 650 Hz sine-wave signal is generated in the circuit IClOc, IClld, C22, C23 # C24, C25, R85r R86, R87 ? R90, and R91. As the gain increases or decreases the phase relation of the supplied signal becomes also larger or smaller with respect to the returning signal* The two signals are compared in the phase detector (ICll) and a new signal is developed. The latter is proportional to the phage and also to the gain. This signal controls the factor k. The gain is laid, out for a phase shift between the signals -of -.135° The " 650 Hz.sine-wave signal is therefore fed into the control loop at pin 13 of IC9d through a 45° phase shifter (R84, C21). The phase shift is 90° at the input of the phase detector. The 650 Hz sine-wave signal is eliminated from the control circuit through a bandpass (IClOd, R82r R83, C19, C20) and converted in IClla to a square-wave signal. This square-wave signal is input to the phase comparator (ICllc, pin 8). The phase reference is supplied by pin 9 of ICllc. 3.3.4 Offset control circuit The asymmetry of the reflected laser beam is corrected by this circuit to ensure that the laser beam is kept exactly on the center of the track. The difference between minimum and maximum reflection is the greatest (presence of pit = minimum reflection, between pits = maximum reflection) when the laser beam follows exactly the center of the track. Through the 650 Hz sine-wave signal the moving arm oscillates with an amplitude of 0.05 jim. If the laser beam is on the track center, all half-waves of the filtered out signal are folded to the same (positive) side. If the laser beam is to the right of the track center, the signal is in~phase with the 650 Hz oscillations of the moving arm, or antiphase if the beam is on the left of the track center. The voltage across R63 is proportional to the reflected light intensity (11 + 12 + I3 + I4). The voltage is amplified through IC6a, R30f R31r and R64 # and the 650 Hz component is filtered out in a bandpass (R32, R33, R34, R35, R37, Cll, C12, and IC7b). The filtered signal is inverted through lC7ar R36, and R38. The former and the noninverted signal are taken to switch C of IC5. The output of this switch (IC5, pin 4) is integrated through IC7d and C.30 and determines the factor d (Q5 and transistor' F of IC8). The status of switch C (IC5) is controlled by the 650 Hz signal in the control loop . -vara-the bandpass R42f R43r R44 , R45, C13, C14 , D4, " and IC7c.
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SECTION 3/8
3 . 3.5 Track detection circuit The tracks which are skimmed over by the laser pick-up are read through the interrupt input of the slave processor (TRK-SIG). This signal is generated from the signal available at IC6, pin 1 (proportional to [ I1 + I2 + I3 + I4J ), the DO and the HFL signal. The signal DO is ,!L,! when no error location is detected on the CD. The HFL signal is "H" when the HF signal is large enough. The TRK signal is only "L" when the HE signal is too small. For each skipped track, HFL is "L" if no error location is detected on the CD (DO="L"). The radial-error signal RE (IC9c, pin 8) informs whether the laser scanner is positioned to the left or the right of the track. The signal required for this purpose (RAD-POS) is generated via IC3c, R12, R19, and R20 from the radial-error signal. 3.4 Preamplifier and laser PCB 1.769.100.35
This board comprises the following circuits: - Laser control - Signals for focus and radial control - HF signal amplifier 3.4.1 Laser control The laser diode is supplied via Q4. The intensity of the laser light can be checked through the "monitor photo diode" and adjusted with the trimmer potentiometer R8CT. The signal LAS-OFF (from PCB 1.769.310 / IC1) switches the laser on or off. If the intensity of the laser becomes too small, the current flowing through the monitor photodiode decreases correspondingly. The voltage across R84 also drops. The output of.opamp IC3a consequently becomes more positive and Q4 more conductive. The intensity of the laser is adjusted by discharging some of the current through the monitor photodiode via R80 and R81. 3.4.2 Focus and radial-control signals The following signals are generated by this circuit; - FOC-ERR - RAD-ERR1 - RAD-ERR2 The currents of the four photodiodes (Al to A4) are amplified in IC1. The corresponding error signals are developed by the subsequent network. The focus error signal is proportional to (11+14) - (12+13). 13 + 14 constitutes the·RAD-ERRl signal, II + 12 the RAD-ERR2 signal. The gain of the focus control loop can be -^djiis/ted with R58, the balance with R41 (not included in 'all versions). " '3-4.3 HF signal amplifier The circuit comprising transistors Ql through Ql constitutes the signal amplifier with bandpass characteristic. Low-frequency (e.g. control signals of the servos) and high-frequency disturbance signals are consequently filtered out. 3.5 Decoder PCB 1.769.300
The decoder PCB contains the following circuits: - Digital signal processing - Digital sine-wave generator - HF£ and DO detector
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SECTION
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3.5.1 Digital signal processing The HF signal is converted in IC13 (SAA 7010} into diqital siqnals and split into audio and information data (subcode, for the slave processor). The CLOCK signal is also regenerated in JC13. The audio data are brought into the correct time slot pattern. Corrupted audio data are not recognized in 1C12 and corrected if necessary. Should the errors be incorrigible, the missing sample values are replaced in. IC10 (SAA 7000) through interpolation. Should this also be infeasible, the HF signal is slowly muted (soft muting). The speed of the CD motor is controlled by the signal MCES (IC1, pin 4 ) . 3.5.2 Digital sine-wave generator The PROM (IC4) contains a value table for the sine-wave signal which represents the maximum possible level of a CD. The circuit consists of IC5 through IC9 with IC5 and IC6 supplying the addresses for the PROM. Parallel/serial data conversion is performed in IC3. The change-over between audio data from the CD and the 1 kHz sine-wave signal is controlled by IC1. · 5 · 3 HFL and DO detector The HF signal is fed into the inverting differential amplifier Ql and Q2 through C6 and R2. The output signals are DC-decoupled via C8 and C9 respectively and tied to DC ground via D2 and D3. D4 and D5 or D6 and D7 respectively constitute a full-wave rectifier each through which the capacitors C10 or Cll are charged. With a normal HF signal the DO signal is "LSi and the HFL signal is "H". If the HF signal drops to approximately 70% of the normal value, the HFL signal also changes to !,Lt! . Only when the HF signal drops to approximately 10% of - the normal value does the DO signal change to "H". To prevent the output signals of IC11 from being influenced too strongly by minor contaminations (e.g. fingerprints) on the CD, transistor Q3 has been added to the output. When the RF level is at nominal value, pin 7 of IC11 is "Hl! . Q3 becomes conductive and the circuit with Cll receives a smaller time constant. With level fluctuations caused by minor contaminations, the levels of the two input capacitors fluctuate in parallel, but neither the DO nor the HFL signal are affected. 3.6 DAC PCS 1.769.280 .
3
Tfee" following'circuits are implemented on this PCB: - Digital filtering (oversampling) and digital/analog - ·conversion - Level adjustment and headphones" aTifffiifier 3.6.1 Digital filtering (oversampling) and D/A conversion IC1 (SAA 7030) contains two identical filters for both channels. These filters feature 3 sections: ~ Oversampling section - Transversal digital f i l t e r - Noise s h a p e r After each scanning cycle, the new sample values are inserted by interpolation into the 16-bit information arriving from the decoder. The scanning rate thus becomes 4 times greater (4 x 44.1 kHz = 176.4 kHz). The spectral lines above 20 kHz up to 176.4 kHz - 20 kHz are filtered out by the transversal filter. The sample values are truncated to 14 bits. The noise shaper subsequently delays the truncation error by the scan duration and negatively added to the next sample value. The guantisizing noise caused by truncation is thereby largely shifted toward the frequency range above 20 kHz. The digital signal is converted in IC101 or IC201 (TDA 1540) to an analog signal. In order to filter out the residual frequency component at n (176.4 kHz + 20 kHz), a low pass of the third order (Bessel filter) ; has been added to the converter output.
r'r:;T*5^ R ^ Q X
B225
SECTION 3/8*
The preemphasis is corrected with the circuit illustratec in Fig. 3.13. The subcode on the CD specifies whether the selection was recorded with or without preemphasis. The characteristic of the corresponding filter can be adjusted with the PREEM signal.
3.6.2 Level adjustment and headphones amplifier The volume is controlled by a DUAL D/A converter (AD7528). It serves as an attenuator before the corresponding input (IC103a, pin 2 = left-hand channel / IC 203bf pin 6 = right-hand channel). The negativefeedback resistances of both opamps remain unchanged which means that the level can only be attenuated with this circuit. The dual D/A converter is controlled by a CMOS shift register through the signals DLEN-3, DATA, and CLK. The circuit illustrated in Fig. 3.14 constitutes the output amplifier for the headphones socket and also the VARIABLE OUTPUT* The signal is also attenuated for this purpose through a voltage divider so that the signal is the same (2 V RMS) at both outputs (FIXED and VARIABLE). The signal is taken through relay Kl in order to prevent power-on switching clicks. When power is applied., the relay is selected by the KILL signal (which rises to +5 V after approximately 1 to 2 seconds). As a result, the outputs are only through-connected when the supply voltages are stable.
REI/OX
B225
SECTION 4/1
4. 4m i
TEST POINTS, ADJUSTMENTS ON B2 2 5 Test points on B225
4.1.1 Test points on SERVO 1 PCB 1.769.310
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B225
SECTION 4/2
I f n o CO i s m o u n t e d w h e n PLAY i s s e l e c t e d * t h e s i g n a l s o n T P 2 6 an CJ 2 7 b e c o m e ^ l ?V i n f o u r i n t e r v a l s o f a p p r o x i m a t e l y o n e s e c o n d each · "
(*)
In PLAY- mode* the signal pattern of these test points on the wobble of the mounted compact disc*
depends
w^rumi
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B225
SECTION 4/3
4.1.2
Test points on SERVO 2 PCB
1.769.330
h FtEMOX
B225
SECTION 4 / 4
when s i g n a l s a r e r e c e i v e d · 4 . 3 V o c c u r on TP52«
froni
the
IR- remote
control t
pulses
of
4.13
T e s t p o i n t s on MICmPRGCESSQR PCB 1.769.320,
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6225
SECTION 4/5
^T'^\£:WM REl/OX
B225
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SECTION 4/6
Test with reference CD part N o . 46241 Black dots are located on track 17 of the disc surface* The following should be measured v^hen this track is played:
WUMEM
FIEMQX
B225
SECTION 4/7
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FIEMQK
B225
SECTION 4/8
4.1.5 Test points on DAC PCB 1,769.280 The internal calibration must be switched on for the following measurements;
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KEI/OX
B225
SECTION 4/9
4 m2 Note:
Adjustments
on C player D
B225
Cleanliness in the work area is of outmost importance and ensures that no contaminants or metal particles can enter into the CD mechanism. If any work on printed circuit boards is necessary, it is essential to observe the ESE recommendations (refer to last page of contents). Before putting the CD player into operation ensure that the transport screws have been unfastened. The CD player mechanism is equipped with self-lubricating bearings which should not be lubricated. If the drawer must be open and a disc mounted in order to perform certain measurements or adjustments, the ·rear light barrier must be interrupted (the detector responds as if the drawer were closed) and the compact disc must be secured with a removed adhesive magnet. The optical system of the laser can be cleaned with an air brush.
Coil Ll on t h e decoder PCB 1.769.300 i s a u t o m a t i c a l l y a l i g n e d by IC13 (SAA7010) and consequently r e q u i r e s no adjustment* 4 . 2 . 1 Aids
DC voltmeter Cathode ray oscilloscope Reference CD, frequency response, part No. 46240 Reference CD, drop outs, part No. 46241 Mirror CD for adjusting the optical system, part No. 46242 - Set of service PCBs and cables, part No. 46230 - ESE work location kit, part No. 46200 4.2.2 Aligning player mechanism, general Remove top cover. Connect CD player to AC supply and open the drawer by pressing the LOAD key. Cover rear light barrier. Mount reference disc 5 (part No. 46241) and secure it with a removed adhesive magnet. Selection 1 of the CD is to be played for all alignment work. It is, therefore^ advantageous to enter the LOOP.-command in programming mode.
-
"4T2". 3 Adjusting the laser current - Switch CD player off, remove SERVO 2 PCB 1.769.330 and reinsert it via the service PCB (part No. 46230). - Connect DC voltmeter to R63 on SERVO 2 PCB. - Adjust the voltage to 500 mV +50 mV with the trimmer potentiometer RS0 (on player mechanism 1.769.100.35). Adjustments should only be made if the measured voltage is outside the specified tolerance range. CAUTION: Voltages above 550 mV shorten the life of the laser pick-up. - Switch CD player off and reinstall SERVO 2 PCB. 4.2.4 Adjusting the balance (if trimmer is present) - Set potentiometer R41 (on player mechanism 1.769.100.35) to its center position.
REMGX
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SECTION 4/10
4.2.5 Adjusting the focus gain - Switch CD player off, remove SERVO 1 PCB 1.76 9.310 and reinsert it via the service PCB. - Connect AF generator to the X input of an oscilloscope and via an R-C-R element (according to Fig. 4.12) to pin 6 of IC2 (on 1.769.310), (f=600 Hz +5 Hz, U=250 to 300 mV RMS). - With trimmer potentiometer R58 (on player mechanism PCB 1.769.100.35), align for minimum amplitude A of the Lissajous figure.
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2 . 6 Checking the angle alignment Place the mirror on the focussing unit and mount the optical system alignment disc (secure with adhesive magnet) . Place the player mechanism below? a light source that produces a linear, straight shadow. Bring the-laser scanner arm to its center position and rotate the CD player in such a way that the arm stands parallel to the line below? the light source (refer to Fig. 4.13). When the reflection on the glass disc and in the mirror is viewed as illustrated in Fig. 4.13. The distance between the two lines should not exceed 2.5 mm.
Position the CD player in such a way that the shadow forms a 90° angle to the scanner arm (see Fig. 4.14). The distance between the two lines (reflections) should not exceed 2.5 mm.
^-yiLr^Ju R ^ O X
B225
SECTION 4/11
The angle alignment must be corrected if the deviation is too large: - Unfasten screw [A] until the support plate [ B] can be shifted. - The support plate can now be shifted according to Fig* 4.5. Retighten the screw [A] when the position is correct. - The angle alignment must be rechecked after the foregoing adjustments have been made. 4.2.7 Adjusting the DC component of the focus signal - Connect DC voltmeter to Rl (SERVO 1 PCB 1.76 9.310). The following adjustment is only necessary if the DC deviation exceeds +JL4 0 mV. Replace the motor if alignment is not possible. - Adjust the axial set screw of the disc motor in such a way that 0 V +_50 mV is measured. - If the motor is replaced, perform the adjustments according to 4.2.6 and 4.2*7* 4.3 4.3.1 Measuring the audio data Aids
-_ Reference CD, part No. 46240 - Automatic distortion meter (e.g. Tektronix AA 501; the RESPONSE button must be in the RMS position for all measurements) - Measuring filter (for distortion measurement) ~ Frequency counter - Oscilloscope 4.3.2 Harmonic distortion
- Measuring arrangement according to Fig. 4.16 - Adjust for maximum level with VOLUME + key - Mount reference disc (part N o . 4 6 2 4 0 ) . Play track 4 for measuring the left-hand channel and track 8 for measuring the right-hand c h a n n e l . - The harmonic distortion should be less than 0.006%. 4.3.3 Output level
- Press CAL TONE button and adjust for maximum level with VOLUME + key. - The level of the FIXED and VARIABLE outputs should be 2 V RMS +10%. The balance between channels should be better than 0.2 dB. 4^,3 . 4 -Frequency response - Adjust for maximum level with VOLUME + key. "'---The calibration tone (1 kHz) serves as the 0 dB reference. - Play tracks 4 and 8 (CD part N o . 46240) and measure the outputs FIXED and VARIABLE. The frequency response shoul-d be within +0 to -X3.6 dB.
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B225
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SECTION 4/12*
4.3.5 Cross talk - Adjust for maximum level with VOLUME + key, - Reference = CAL TONE 1000 Hz) - Measure both outputs across a 30 kHz low-pass: Play track 8 for measuring cross talk R -> L Play track 4 for measuring cross talk L -> R - The cross talk attenuation should be at least 90 dB. 4.3.6 Signal-to-noise ratio, linear
- Maximum volume, reference = CAL TONE 1000 Hz. - Play track 18 and measure the outputs FIXED and VARIABLE via a 30 kHz low-pass. - The measured value should be higher than -96 dB, 4.3.7 Signal-to-noise ratio, weighted
- Maximum volume, reference = CAL TONE 1000 H z . - Play track 18 and measure the outputs FIXED and VARIABLE via an A filter. - The measured value should be higher than 100 dB, 4.3.8 Phase linearity
- Connect oscilloscope to one of the outputs. - Play track 20 and visually assess the square-wave signals at 100 Hz, 400 H z , 1002 H z , and 5512 H z . The curve should be shaped symmetrically (see F i g . 4.17). , . 4.4 Listening test with reference CD (part No. 4 6241)
The reference CD simulates the following errors for checking the error correction system: - Information gaps with a length of 400 to 900 pm (tracks 5 through 9) - Black dots from 300 to 800 micrometers (tracks 1 1 through track 17) * - Simulated fingerprint (tracks 18 and 19) The simulated defects should not cause any drop-outs (reproduction g a p s ) . If drop-outs become audible, this can for example be caused by the following errors: - IC13 (SAA 7010, demodulator), clock w i t h PLL defect. - H F L an DO detector defective. regeneration