PIONEER CX893 - Service Manual Immediate Download

PIONEER ELECTRONIC 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. 501 Orchard Road, #10-00, Wheelock Place, Singapore 238880

C PIONEER ELECTRONIC CORPORATION 1998

K-ZZB. OCT. 1998 Printed in Japan

ORDER NO.

CRT2291

MD MECHANISM MODULE

CX-893

Service

Manual

CONTENTS

1. CIRCUIT DESCRIPTIONS...........................................2

2. DISASSEMBLY.........................................................13

- This service manual outlines operations of the MD mechanism module used in the models listed

below.

- For repair, use this Service Manual and the Service Manual of the model used in the system.

Model

Service manual

MD mechanism module

MEH-P5000R/EW

CRT2287

CXB2784

Figure 1 below shows the block diagram. This block

controls the output from the block LD to be consistent

with the monitor diode.

The block consists of IC 102 and turned to LD ON when

LDON (6 pin) is H and to LD OFF when LDON is L. LD

output level is set with the voltage value of LDVAR and

is usually around 2.4 V.

CX-893

1. CIRCUIT DESCRIPTION

1.1 APC Part

Fig.1

1.2 RF amplifying part

The block amplifies the pickup output signal and

generates RF and ADIP signals.

This block mainly consists of IC101.

REFO part

REFO (+1.5 V) is the reference voltage for the servo.

The signal is resistive divided at the IC (REFI: 5 pin) and

output to 6 pin through buffer. This signal will be the

reference for RFIC.

RF signal amplifying part

Figure 2 below shows the block diagram. The signal

which is I-V converted at the pickup is input to the RF1-4

(1-4 pin). Gain at the I-V amplifier contained in the PU

is switched depending on the disc types. The switching

is controlled by OPICGA (IC401, 61 pin) and H is output

at Premaster DISC and L is output at Recordable DISC.

The signal input from the I-V amplifier is operated with

the contained resistance and amplifiers (A1, A2) and the

signal (RF1 + RF2 + RF3 + RF4) (POUT) and the signal

(RF1 + RF2 + RF3 - RF4) (GOUT) are generated. Each of

POUT and GOUT is equipped with an analog switch.

The switches are controlled with the DISC signal (bits

on microprocessor serial communications). The POUT

signal is output through 48 pin when the DISC signal is

H (PIT mode) and GOUT signal is output through 47 pin

when the DISC signal is L (GRV mode).

These signals are input to EFMAGC (45 pin) through the

coupling capacitors (C133, C112) and transmitted to the

AGC circuit and filter part to be output from EFMO (40

pin). The EFMO is maintained at almost same level

(approx. 1.5 Vpp) with the AGC circuit. These signals

are input to the signal processing part (IC201: 3 pin) and

used for data processing and spindle control when

playing a Premaster Disc.

CX-893

Fig.2

ADIP signal amplifying part

Figure 3 shows the block diagram of this part. The block

generates the ADIP signal which exists only on a

Recordable DISC of a MD.

Signals input to RF1 and RF2 (1,2 pin) are transmitted

through the AGC part and the filter part to be output to

22KO (32 pin). The 22KO is designed to be maintained

at almost same level (approx. 1.2 Vpp) with the AGC

circuit. However, fluctuation of about +0.5V may be

observed due to core components, responsibility of

tracking servo, etc. The signal is then converted to 1

and 0 signal with the comparator C1, input to the signal

processing part (IC201:11 pin), and used for address

control when playing disc for recording and spindle

control.

*Will not be used when Premaster Disc is played.

Fig.3

CX-893

Track cross part, signal amplifying part for servo

Figure 4 shows the block diagram of these parts.

The signal input to RF1-4 (1-4 pin) is resistive divided

and amplified to be output to TCGO (29 pin). TCGO is

input to the signal processing part (IC201:7 pin) and

TCRS signal is generated and will be used when the

system skips tracks to play.

Outputs from the focus servo based photo diode are

input to AIN (9 pin) and BIN (10 pin) and are output to

AOUT (28 pin) and BOUT (27 pin), respectively, after

being amplified.

Outputs from focus servo based photo diode are input

to EIN (11 pin) and FIN (12 pin) and are output to EOUT

(26 pin) and FOUT (25 pin), respectively, after being

amplified .

These signals are input to the signal processing part

(IC201: 5,6,7,8,9 pin) and used at each servo.

Amplifying ratios of each signal are controlled by the

microprocessor and adjusted so that they reach

optimized values when mechanical modules are

shipped. Those optimized values are stored in IC402.

Therefore, when you replace IC or PU switch, etc., you

should have the IC402 memorize new optimized values

by turning EEPROM (IC402) to write mode (See the

relevant sections for details.) and running test modes

AUTO1 and AUTO2 with a Recordable DISC (MMD-211

or MMD-212).

Fig.4

CX-893

Logic part

Serial commands of the microprocessor determines the

setting of this IC.

Timing chart

DATA (23pin)

CLOCK (22pin)

LATCH (21pin)

MSB

7SB

6SB

5SB

4SB

3SB

2SB

1SB

Structure of serial data

MSB

7SB

6SB

5SB

4SB

3SB

2SB

1SB

Pattern A

Focus gain

Tracking gain

Pattern B

STBY

DISC

SGAIN Track loss gain

Gain setting (+12dB when SGAIN=H at normal operation)

Setting value

Focus gain

Tracking gain

Track loss gain

000

001

010

011

100

101

110

111

STBY: Switches to stand-by mode

H: Normal L: Stand-by

DISC: Switches to disc mode

H: PIT (Premaster Disc)

L: GRV (Recordable Disc)

SGAIN: Switch of amplifier gain for servo

H: +12dB

L: Normal