Pioneer CX-961 User manual

Model Service Manual CD Mechanism Module
DEH-P90DAB/EW, ES CRT2556 CXK5301
PIONEER CORPORATION 4-1, 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.
PIONEER EUROPE NV Haven 1087 Keetberglaan 1, 9120 Melsele, Belgium
PIONEER ELECTRONICS ASIACENTRE PTE.LTD. 253 Alexandra Road, #04-01, Singapore 159936
C PIONEER CORPORATION 2000 K-ZZA. NOV. 2000 Printed in Japan
ORDER NO.
CRT2503
CD MECHANISM MODULE
CX-961
Service
Manual
-This service manual describes the 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.................................15
3. DISASSEMBLY .........................................................17

2
C X-961
1. CIRCUIT DESCRIPTIONS
This unit is roughly divided into the preamplifier stage, servo unit, power supply unit and loading control unit. This
LSI (large scale integrated circuit) implements eight automatic adjustments according to the combination of the
preamplifier stage and servo unit used.
Besides, because this system conforms to the single power supply (+5 V) specifications, the reference voltages of
servo systems (preamplifier, servo DSP and pickup) are all Vref (2. 1 V).
1.1 Preamplifier (TA2150FN; IC201)
The preamplifier processes output signal from the
pickup, then generates signals to the servo unit,
demodulator unit and control unit at the next stage, and
controls power for the pickup’s laser diode. The signal
from the pickup is I-V converted by the preamplifier
built into the pickup’s photodetector, then added by the
RF amplifier to obtain such signals as RF, FE and TE.
Reference voltage Vref (2.1 V) is output from pin 19 of
this IC and 2 Vref (4.2 V) is supplied as the reference
voltage which determines the D range of the servo DSP
A/D input.
Fig.1:TA2150FN CIRCUIT

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2) Tracking error amplifier unit
This tracking error amplifier unit outputs photodetector
output E or F from pin 14 of IC201 (TA2150FN)via an
amplifier and an error amplifier assuming (E - F) as a TE
signal. The low frequency component of voltage TE is
expressed as
TE = (E - F) ×300 k / 100 k ×155 k / 328 k ×82 k / 20 k =
5.8 times.
A TE waveform of approximately 1.51 Vpp is obtained
in the TE output on the basis of Vref. The cutoff
frequency is 44.5 kHz or 29.4 kHz.
1) Focus error amplifier unit
This focus error amplifier outputs photodetector output
(A + C) or (B + D) from pin 16 of IC201 (TA2150FN) via a
differential amplifier and an error amplifier assuming
(A + C - B -C) as an FE signal. The low frequency
component of voltage FE is expressed as
FE = (A + C - B - D) ×(150 k / 62 k) ×(60 k / 60 k) ×(12 k /
60 k) = 4.84 times.
An S curve of approximately 1.45 Vpp is obtained in the
FE output on the basis of Vref. The cutoff frequency is
26 kHz or 133 kHz.
Fig.2:FE CIRCUIT
Fig.3:TE CIRCUIT

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C X-961
3) RF amplifier unit
The head amplifier LSI, TA2150FN, adds, amplifies and
equalizes photodetector output (A+C) and (B+D), then
outputs RF signal to the RFI pin. (This signal enables
checking eye patterns.) Low frequency element
contained in RFI voltage is formulated as follows:
RFI = (A + B + C + D) ×5.43.
RFI is used for RF Offset Control circuit. RFI signal
output from Pin 28 is AC-coupled externally, and then
re-input to Pin 27 and amplified by the RFAG amplifier
to obtain RFO signal.
As described later, TA2150FN has a built-in RFAGC
function that controls the RFAGC amplifier gain so that
RFO output stays within 1.2 ± 0.3V p.p. range.
This RFO signal is used for EFM and RFAGC control
circuit and for generating RFRP and RFCT signals for
track counting.
Besides, the frequency characteristics of an RF
equalizer are switched at double-speed reproduction.
(Switching using the HSSW terminal)
Further, with RWSW the gain at the RF amplifier stage
is raised by 13db, compared with that in normal
operation, when the gain lowers because of stains on
the lens or while playing a CDRW.
Fig.4:RF CIRCUIT

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C X-961
4) RFRP and RFCT signal circuit unit
The RFCT signal which is the difference signal between
the peak and bottom levels of the RF signal is
generated through head amplifier (IC201). RFRP and
RFCT can be monitored at TP203 (pin 20 of IC201
TA2150FN) and TP204 (pin 22 of IC201) respectively.
The TE, RFRP and RFCT signals are compared by a
hysteresis comparator inside IC301 (TC9495FP)
respectively and generate track information (TEZC
signal or RFZC signal). Based on this signal, the
traveling speed information about a lens disk is
generated and the number of tracks is counted.
5) SBAD signal circuit unit
This SBAD signal circuit unit outputs photodetector
output E and F from IC201 (pin 15 of TA2150FN) via an
addition amplifier assuming (E + F) as an SBAD signal.
This SBAD signal is used as the internal decision
conditions of focus ON/OFF with a focus error signal.
Further, the SBAD signal is also used for detecting
defects when disk scratches are passed.
Fig.5:RFRP AND RFCT SIGNAL CIRCUIT
Fig.6:SBAD SIGNAL CIRCUIT

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6) APC circuit section
A laser diode’s driving current must be controlled so that
optical output could remain constant by using a monitoring
diode, because optical output has high negative
characteristics that causes a heat hang-up if the laser diode
were driven at constant current. This is exactly where APC
circuit works. LD current can be obtained by measuring
voltage between LD1 and GND, which value is about 35 mA
at room temperature.
1.2 Servo DSP (TC9495FP; IC301)
1) Focus servo system
The main equalizer of the focus servo is comprised with a
digital equalizer unit. Fig. 8 shows a block diagram of the
focus servo.
Fig.7:APC CIRCUIT
IC401 BA5811FM
FOP
IC301 TC9495FP
DAC
A/D
FOCUS
EQUALIZER
FE FEI
FOO
FD
FOM
C
N
O
T
R
L
O
FOCUS SEARCH
WAVEFORM
GENERATION CIRCUIT
43
13
48
14
5
Fig.8:FOCUS SERVO CIRCUIT BLOCK

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The operation of detecting an adjusted focus point and
turning on the focus servo is called focus search. In a
focus servo system, a lens needs to move to the
adjusted focus point to enable focus close.
Accordingly, the adjusted focus point is detected by
moving the lens up and down according to the focus
search voltage of a triangular wave. Further, in the
meantime, a spindle motor enters the simplified FG
mode and maintains a constant speed of rotation. The
focus servo turns on under the following three
conditions:
1. FOK = H
2. A focus error signal exceeds a focus standby level
threshold.
3. A focus error signal reaches a zero cross.
At this time, while the lens is fully separated from the
adjusted focus point, cancel the SBAD offset and set
this level to SBOFF. If the SBAD level exceeds the FOK
threshold from the SBOFF standard, FOK = “H”is set.
When the lens moves up and down, a focus error signal
changes at the adjusted focus point. However, CD-LSI
removes an offset component by passing through a
bypass filter after it has A/D-converted this error signal.
When this FEHPE signal (LSI signal) level exceeds a
focus standby high level, the servo standby state
occurs because the adjusted focus point approaches.
Subsequently, the FEHPF signal reaches the adjusted
focus point and turns on the focus servo.
The microcomputer monitors an FOON signal (Active at
servo ON; L for a probe) at focus search, and starts
monitoring a FOK signal in 40 ms after it has been set
to Active). If it is judged that FOK is not active, the
microcomputer performs protection operation.
Besides, when the Focus Close button is pressed with
the focus mode select set to Display 01 in the test
mode, a focus error, search voltage and the action of a
practical lens can be checked.
2) Tracking servo system
The main equalizer of the tracking servo is comprised
with a digital equalizer unit. Fig. 10 shows a block
diagram of the tracking servo.
Fig.9:FOCUS SEARCH TIMING
→
OFFSET
FOCUS SERVO ON
FEI INPUT WAVEFORM : FE HIGH PASS FILTER OUTPUT : FEHPF
HIGH PASS FILTER
STANDBY
LEVEL
F1
F1
FOCUS SERVO ON
REF LEVEL
STANDBY LEVEL : F1
15.(3)
FOCUS SERVO ON
REF LEVEL
FEHPF
SBAD
FOK
FOON
FOK LEVEL
88.1kHz×
127 SAMPLE
SBOFF LEVEL
DEFECT(SCRATCHES)
=TOK
IC401
BA5811FM
CARRIAGE
MOTOR
COM
TOP
"
IC301 TC9495FP
DAC
A/D
TRACKING
EQ
+
AT THE TIME OF LENS KICK
TE TEI TRO
M
TD
TOM
COP
CARRIAGE
EQ
+
PWM
FMO
AT THE TIME OF FEED KICK
JUMP
CONTROL
TEZI
RFRP
SD
46
47
49
53
6
16
15
12
11
25
26
42
Fig.10:TRACKING SERVO CIRCUIT BLOCK

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•Track jump
A track jump is automatically performed with a
microcomputer command using the LSI auto
(automatic) sequence function.
This system has one to 99 lens kick modes as the track
jump used at search and the carriage move used in the
jump exceeding 1,000 tracks. The test mode can check
the jump of lens kick modes 1, 32 and 99 and the
carriage move according to the mode selection.
•Lens kick Jump
Lens Kick jump is executed as soon as the LSI receives
the Lens Kick command from the microcomputer. The
direction of jump and the number of tracks are
determined by the command’s parameters. When the
LSI receives the Lens Kick command, the jump is
performed by inputting a kick pulse to the tracking EQ.
The LSI controls lens traveling speed, referencing to the
table held internally. By doing so, the lens travels faster
when there are a good number of tracks to go, while
the lens traveling speed gets slower as the remaining
tracks decrease. After track count has been completed,
tracking close is performed. During jump, an RFRP
signal is watched to perform track count and the
direction of the jump is detected according to the phase
of RFRP or TEZI. Besides, to improve the servo feed at
track jump, the tracking servo gain increase and
hysteresis operation are performed for 50 ms after
tracking close has been completed. The FF/REV
operation in the normal mode is implemented by
continuously performing a single jump. The speed is
about 10 or 20 times the normal mode. (It depends on
destinations).
•Carriage move jump
A carriage move jump is executed by issuing a carriage
move command from the microcomputer. The
direction of the move and the number of tracks are
specified with the command. When the LSI accepts the
carriage move command, the jump is performed by
opening the tracking servo, applying a kick signal to the
carriage equalizer and driving the carriage motor. The
profile of a signal applied in this time is provided with a
time constant at rise time. As the remaining tracks
decrease, voltage is lowered that results in slower
carriage traveling speed.
The servo feed at the end of the jump is improved by
reducing the speed in this manner immediately before
the jump terminates.
Besides, to improve the servo feed at the end of the
jump, the tracking servo gain increase and hysteresis
operation are performed for 60 ms after the jump has
been performed.
EQUALIZER
HYSTERESIS
CLOSE
GAIN UP
NORMA
L
TE
RFZC
(LSI INTERNAL SIGNAL
PRODUCED FROM RFRP)
(LSI INTERNAL SIGNAL
PRODUCED FROM TEI)
TEZC
SERVO
OPEN
ON
OFF
50ms
THE HYSTERESIS OPERATION
OF THE1-4 TRACK JUMP IS 2 ms.
50ms
Fig.11:LENS KICK
SD
TE
SERVO
EQUALIZER
HYSTERESIS
OPEN
CLOSE
GAIN UP
NORMAL
ON
OFF
60ms
60ms
Fig.12:CARRIAGE MOVE

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•Hysteresis operation
Because the servo feed is deteriorated at setup and
track jump, hysteresis is operated to perform a servo
feed to a stable servo loop. The hysteresis operation
holds a TE signal and improves the convergence of the
tracking servo when a beam spot arrives at an off track.
3) Carriage servo system
The carriage servo inputs the output of the low
frequency component (lens position information) of the
tracking equalizer to the carriage equalizer, and outputs
a drive signal from the LSI after a fixed gain has been
obtained. The signal further applies to the carriage
motor via the driver. Specifically, because the entire
pickup needs to move to the forward direction when
the lens offset during play reaches a certain level, the
gain of the equalizer is set so as to output a higher
voltage than the starting voltage of the carriage motor
at that time. Besides, as a practical operation, only
when a threshold level against the equalizer output is
exceeded inside the servo LSI, a drive voltage is output.
The threshold level is set slightly higher than the
starting voltage of the motor to reduce power
consumption and stabilize operation. This drive output
waveform has a pulse shape.
Fig.14:CARRIAGE SERVO CIRCUIT BLOCK
Fig.15:CARRIAGE SIGNAL WAVEFORM
DIGITAL
EQUALIZER
CONTROL
PMW
OUTPUT
CIRCUIT
COP
COM
CRG
MOTOR
IC401
BA5811FM
SD
FMO
M
IC301 TC9495FP
from
TRACKING
EQUALIZER
16
15
25
26
53
TRACKING DRIVE
(LOW FREQUENCY)
LENS POSITION
CRG MOTOR VOLTAGE
DRIVE ON/OFF THRESHOLD
CRG DRIVE
(INSIDE TC9495FP)
CRG moved at these point
4) Spindle Servo System
Fig. 16 shows a block diagram of the spindle servo.
The spindle servo has the following modes:
•CLV servo
This CLV servo mode is the servo until the brake is
applied to stop the disk after focus close. The spindle
servo operates in this mode before tracking close and
at normal reproduction.
In the EFM demodulation block inside the CD-LSI, the
spindle servo performs synchronous detection and
operates so as be kept in a specified speed of rotation.
The synchronous detection is also enabled before
tracking close by using the VCO speed control of the
inside of the LSI in the PLL circuit. After tracking close,
the VCO speed control is muted and switched to the
speed and phase control by a master clock (a ceramic
oscillator is used).
IC401
BA5811FM
IC301 TC9495FP
PWM
SYNCHRO-
NOUS
DETECTION
MD
DIGITAL
Eq.
EFM
EC
Brushless
Motor Unit
Mechanism Unit
SPEEDERROR
PHASEERROR
FG
VCO
Master
Clock
23 22
54
TE
SIGNAL
DIRECTION OF THE EXTERNAL SURFACE DIRECTION OF THE INTERNAL SURFACE
RFRP
SIGNAL
AFTER
TE SIGNAL
HOLD
ON TRACK ON TRACK
ON TRACK ON TRACK
Fig.13:HYSTERESIS OPERATION
Fig.16:SPINDLE SERVO CIRCUIT BLOCK

10
C X-961
•Simplified FG servo mode
This simplified FG servo mode is used to maintain the
number of disk rotations in the state of the approximate
number of regular rotations. In this mode, controlling
driving voltage for the spindle motor is enabled by
letting the microcomputer monitor FG signal that
outputs pulses based on the number of rotations. The
mode is used in the following conditions:
a) Until focus close is performed from POWER ON at
setup
b) Until focus is out of order during play and recovered
later
•Brake mode
This brake mode is used to stop the spindle motor. The
brake sequence is started by issuing a CD-LSI
command from the microcomputer. The LSI sets a flag
on by detecting that the number of disk rotations was
set to approximately one twentieth. This flag is
monitored by the microcomputer to set the servo off.
When no flag is set on even if a fixed time elapses, the
brake mode enters the stop mode until it is checked
that the rotation was delayed by monitoring the FG
pulse. If the mode is switched to the stop mode at
ejection, the operation moves to the ejection operation
after the timeout time elapses.
•Stop mode
This stop mode is used at POWER ON and ejection.
The drive output is 0.
1.3 Automatic Adjustment Function
This system automates all circuit adjustments inside
CD-LSI (IC301: TC9495FP). All the adjustments are
performed every time at disk insertion or source key CD
mode selection.
The contents of each automatic adjustment are
described.
1) Automatic TE and FE offset controls
These controls are used, at powering on, to have the TE
and FE amplifiers’offset value stay within the target
range using Vref as a reference. (The target is (TE, FE)
= (0, 0) [V]) respectively.
The adjustment procedures are as follows:
(1) The servo LSI reads each offset of the laser diode
OFF state.
(2) Calculate voltage to be offset based on the value
read into earlier, and then assign the offset value to the
given location. Besides, because this adjustment is
performed inside a digital filter, no change cannot be
found as an error offset voltage after adjustment.
2) Automatic tracking balance (T. BAL)
control
This control is used to equalize output difference
between Ech and Fch from the pickup by adjusting the
preamplifier’s internal gain. In practice, a TE waveform
is adjusted so as to become symmetric vertically for a
servo reference level.
The adjustment procedures are as follows:
(1) After focus close
(2) Turn on the spindle servo.
(3) Calculate a TE center value according to the
introduced TE signal and TE offset levels in the LSI.
(4) This center value changes the gain of the RF
amplifier so as to approach to a servo reference level.
The servo reference level is as follows:
TEI input level at servo OFF (= TE offset level) when
offset adjustment is performed
Vref level when no offset adjustment is performed
To improve adjustment accuracy, the adjustment is
repeated several times.
A/D
DETECTION OF
THE BOTTOM
VALUE
FREQUENCY
MONITOR
DIGITAL
EQUALIZER
FILTER
AVERAGING
+
DECISION
WINDOW
PWM
OUTPUT
CIRCUIT
TEBC
IC301 TC9495FP
IC201 TA2150FN
TEI
TEB TE
46
52
11 14
DETECTION OF
THE PEAK
VALUE
+
AVERAGE OF
128 SAMPLES
OFFSET
RESISTOR
DIGITAL
EQUALIZER
A/D
+
-
FEI
TEI D/A
IC301 TC9495FP
43or
46pin
Fig.17:OFFSET ADJUSTMENT
Fig.18:TRACKING BALANCE ADJUSTMENT