Pioneer CX-958 Service manual

Model No. Order No. CD Mechanism Module Mechanism Unit DEH-P410/X1N/UC CRT2414 CXK5201 CXB4800 DEH-P4100/X1N/UC DEH-P310/X1N/UC DEH-P41/X1N/UC CRT2415 CXK5201 CXB4800 DEH-P3100/X1N/UC DEH-P4150/X1N/ES CRT2416 CXK5201 CXB4800 DEH-P3150/X1N/ES DEH-P4100R/X1N/EW CRT2417 CXK5201 CXB4800 DEH-3110/X1N/EE DEH-3130R/X1N/EW CRT2418 CXK5201 CXB4800 DEH-3100R-B/X1N/EW DEH-3100R/X1N/EW

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 ELECTRONIC [EUROPE] N.V. Haven 1087 Keetberglaan 1, 9120 Melsele, Belgium PIONEER ELECTRONICS ASIACENTRE PTE.LTD. 253 Alexandra Road, #04-01, Singapore 159936

C PIONEER CORPORATION 1999

K-ZZA. OCT. 1999 Printed in Japan

ORDER NO.

CRT2423

CD MECHANISM MODULE

CX-958

- This service manual describes the operation of the CD mechanism 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.................................17

3. DISASSEMBLY .........................................................18

CX-958

1. CIRCUIT DESCRIPTIONS

The LSI (UPD63711GC) used on this unit comprises six main blocks ; the pre-amp section, servo, signal processor, DAC, CD text decoder (not used on this model) and LPF. It also equips with nine automatic adjustment functions.

1.1 PRE-AMP SECTION

This section processes the pickup output signals to create the signals for the servo, demodulator and control. The pickup output signals are I-V converted by the preamp with the built-in photo-detector in the pickup, then added by the RF amp to obtain RF, FE, TE, TE zero cross and other signals. This pre-amp section is built in the servo LSI UPD63711GC (IC201). The following describes function of each section. Since this system has a single power supply (+5V), the reference voltage for this LSI and pickup are set to REFO (2.5V). The REFO is obtained by passing the REFOUT from the LSI through the buffer amplifier. The REFO is output from Pin 89 of this LSI. All measurements are done using this REFO as reference. Note : During the measurement, do not try to short the REFO and GND.

1) APC Circuit (Automatic Power Control)

When the laser diode is driven with constant current, the optical output has large negative temperature characteristics. Thus, the current must be controlled from the monitor diode so that the output may be constant. APC circuit is for it. The LD current is obtained by measuring the voltage between LD1 and V+5. The value of this current is about 35mA.

Fig.1 : BLOCK DIAGRAM OF BUILT-IN RF AMPLIFIER

Fig.2 : APC CIRCUIT

EFM

ASY

AGCO

AGCI

RFO

EQ2

EQ1

RFI

RF-

Vref

VREG

GND APN

LDON

Vref

PEAK DET.

Vref

BOTTOM DET.

LPF

S/H

Vref

D/A

Vref

D/A

Vref

A/D

C-3T

FEO

FE-

TEO

TE-

TE2

EFM

MIRR

DEFECT

A3T

FOK

To the following stage of the LSI

16k

VREG

GND

AMP_PN (H:Nch L:Pch)

LDON (H:LD MOVE L:STOP)

·····Vref(+2.5V)

+5V

C103

150k

·····Vref(+2.5V)

Vref

100k

110k

100µF/6.3V

Q101

2SB1132

C102

0.1µF

R102 10 R101 12

PU UNIT

R103

C105

2.2k

0.33µF

CX-958

2) RF Amplifier and RFAGC Amplifier

The photo-detector outputs (A +C) and (B +D) are added, amplified and equalized on this LSI and then output to the RFI terminal as the RF signal. (The eye pattern can be checked by this signal.) The RFI voltage low frequency component is :

RFI = (A +B +C +D) ×3.2 RFI is used on the FOK generator circuit and RF offset adjusting circuit. R207 is an offset resistor for maintaining the bottom reference voltage of the RFI signal at 1.5 VDC. The D/A output used for the RF offset adjustment (to be described later) is entered via this resistor. After the RFI signal from Pin 77 is externally AC coupled, entered to Pin 76 again, then amplified on the RFAGC amplifier to obtain the RFO signal. The RFAGC adjustment function (to be described later) built-in the LSI is used for switching feedback gain of the RFAGC amplifier so that the RFO output may go to

1.5 ±0.3Vpp. The RFO signal is used for the EFM, DFCT, MIRR and RFAGC adjustment circuits.

3) RFOK Circuit

This circuit generates the signal that is used for indicating the timing of closing the focus or state of the focus close currently being played. This signal is output from Pin 4 as the FOK signal. It goes high when the focus close and in-play. The RFOK signal is generated by holding DC level of the RFI at its peak with the succeeding digital section, then comparing it at a specific threshold level. Thus, the RFOK signal goes high even if the pit is absent. It indicates that the focus close can take place on the disc mirror surface, too. This signal is also supplied to the micro computer via the low pass filter as the FOK signal and used for the protection and the RF amplifier gain switching.

Fig.3 : RFAMP, RFAGC AND FOK CIRCUIT

CN101

A+C

B+D

C216 3pF

R205 10k

C217 27pF

R207

12k

D/A

10k

16k

R206

1.8k

80 79 74757677

10k

R204 10k

C215

0.1µF

A/D

10k

12k

3900pF

RFOAGCIRFI

FOK

CIRCUIT

C213

TO EFM

CIRCUIT

FOK

CX-958

Fig.5 TRACKING ERROR AMPLIFIER AND TRACKING ZERO CROSSING AMPLIFIER

4) Focus Error Amplifier

The photo-detector outputs (A+C) and (B+D) are passed through a differential amplifier and an error amplifier, and then (A+C−B−D) is output from Pin 91 as the FE signal. The FE voltage low frequency component is :

FE = (A + C − B − D) ××

= (A + C − B − D) × 5

Using REFO as the reference, an S-curve of approximately 1.5 Vpp is obtained for the FE output. The final-stage amplifier cutoff frequency is 11.4 kHz.

5) Tracking Error Amplifier

The photo-detector outputs E and F are passed through a differential amplifier and an error amplifier, and then (E −F) is output from Pin 93 as the TE signal. The TE voltage low frequency component is :

TE =(E −F)

××

(E −F) ×6.6 (Effective LSI output is 5.0). Using REFO as the reference, the TE waveform of approximately 1.3 Vpp is obtained for the TE output. The final-stage amplifier cutoff frequency is 20 kHz.

6) Tracking Zero Crossing Amplifier

TEC signal (the tracking zero crossing signal) is obtained by multiplying the TE signal four times. It is used for locating the zero crossing points of the tracking error. The zero cross point detection is done for the following two reasons :

To count tracks for carriage moves and track jumps.

To detect the direction in which the lens is moving

when the tracking is closed (it is used on the tracking brake circuit to be described later).

The TEC signal frequency range is 300 Hz to 20 kHz.

TEC voltage =TE level ×4 Theoretical TEC level is 5.2V. The signal exceeds Drange of the operational amplifier and thus is clipped. It, however, can be ignored since this signal is used by the servo LSI only at the zero crossing point.

20k5k

CN101

10k

20k

A+C

16k

B+D

48k

16k

10k

9190

D/A

80k

110k

C219 180pF

A/D

FE OFFSET

TO DIG. EQ

48k

48.7k

CN101

112k

48.7k

224k

48k

224k

112k

9392

D/A

80k

110k

C220 51pF

80k

110k

A/D

TE OFFSET

TO DIG. EQ

48k

60k

20k

TE2

TEC

C221

6800pF

16k 10k

80k

(20k + 5k)

Fig.4 : FOCUS ERROR AMPLIFIER

224k 112k

160k

48.7k

CX-958

7) DFCT (Defect) Circuit

The DFCT signal is used for detecting defects on the mirrored disc surface. It allows monitoring from the HOLD pin (Pin 2). It goes high when defects are found on the mirrored surface. The DFCT signal is generated by comparing the RF amplified signal (which is obtained by bottom holding the RFO signal) at a specific threshold level by the succeeding digital section. Stains or scratches on the disc can constitute the defects on the mirrored disc surface. Thus, as long as the DFCT signal remains high in the LSI, the focus and tracking servo drives are held in the current state so that a better defect prevention may be ensured.

8) 3TOUT Circuit

The 3TOUT signal is generated by entering disturbance to the focus servo loop, comparing phase of fluctuations of the RF signal 3T component against that of the FE signal at that time, then converting the signal to DC level. This signal is used for adjusting bias of the FE signal (to be described later). This signal is not output from the LSI, thus its monitoring is not available.

9) MIRR (Mirror) Circuit

The MIRR signal shows the on track and off track data, and is output from Pin 3. When the laser beam is

On track : MIRR ="L"

Off track : MIRR ="H" This signal is used on the brake circuit (to be described later) and also as the trigger to turn on track counting when jumping take place. The MIRR signal is supplied to the micro computer, too, for the protection purpose.

A/D

MIRR

CIRCUIT

DFCT

CIRCUIT

BOTTOM DETECT

PEAK DETECT

LPFS/H

A/D

40k

20k

40k

200k

C212

0.1µF

C3T

AGCI

RFO

12k

10k

20k

30k

MIRR

HOLD

Fig.6 : DFCT, MIRR AND 3T DETECTION CIRCUIT

Fig.7 : HOLD OUTPUT WAVEFORM

(When surface defects are present)

Fig.8 : MIRR OUTPUT WAVEFORM

(When an access is made)

Surface defects

RFI

HOLD

RFI

MIRR

OFF Track ON Track

CX-958

10) EFM Circuit

This circuit is used for converting the RF signal to digital signal consisting of “0” and “1”. The RFO signal from Pin 75 is externally AC coupled, entered to Pin 74, then applied to the EFM circuit. Loss of the RF signal due to scratches or stains on the disc, or vertical asymmetry of the RF due to variations in the discs manufactured can’t be eliminated by AC coupling alone. This circuit, therefore, controls the reference voltage ASY on the EFM comparator by use of the fact that “0” and “1” appear fifty fifty in the EFM signal. By this arrangement, the comparate level is constantly maintained at almost center of the RFO signal level. The reference voltage ASY is generated when the EFM comparator output is passed through the low pass filter. The EFM signal is output from Pin

71. It is a 2.5 Vp-p amplitude signal centering on REFO.

Fig.9 : EFM CIRCUIT

C213

3900pF

RFI

EFM. SIG

40k

15k75k

40k

EFM

ASY

C211

0.1µF

R202

10k

R203

39k

C210

3300pF

+ 14 hidden pages