Pioneer CX-977 Service manual

Model Service Manual CD Mechanism Module DEH-P630/X1N/UC CRT2648 CXK5500 DEH-P7300R/X1N/EW CRT2649 DEH-P730/X1N/UC CRT2650 DEH-P7350/X1N/ES CRT2651

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 2001

K-ZZA. MAR. 2001 Printed in Japan

ORDER NO.

CRT2624

CD MECHANISM MODULE

CX-977

- 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.................................26

3. DISASSEMBLY .........................................................28

C X-97 7

1. CIRCUIT DESCRIPTIONS

From divisional viewpoint, the CX-977 is roughly divided into four sections, namely, Preamplifier, Servo, Power Supply

and Loading Control.

This LSI realizes eight types of automatic adjustments (controls) through cooperative work between Preamplifier and

Servo unit.

Because the system uses the single power source (+ 5v) specification, reference voltages used in the servo system

(Preamplifier, Servo DSP and Pickup) are all Vref (2.1V).

1.1 PREAMPLIFIER (TA2153FN; IC101)

The Preamplifier processes output signals sent from the Pickup and generates signals to supply to each unit of the

next stage, that is, Servo, Demodulator or Control. It also performs power control of Pickup's laser diode. Signals from

the Pickup are I-V-converted by the Preamplifier, which is built-in in Pickup's photo detector, and then added-up by the

RF amplifier to obtain signals such as RF, FE and TE.

Reference voltage, Vref (2.1v), is output from #19 pin of the IC, and 2Vref (4.2v) is supplied to the Servo DSP as the

reference voltage to determine its D range of A/D input.

Fig. 1: TA2153FN circuit

C X-97 7

1) Focus Error Amplifier unit

In this sub-unit, outputs from the photo detector, namely, (A+C) and (B+D), are processed in the differential amplifier

and further in the error amplifier, and then, (A+C-B-D) is output as FE signal from #16 pin of IC101 (TA2153FN).

Low frequency component of voltage FE is expressed as:

FE = (A+C-B-D) x (150k/(51k+1k)) x (60k/60k) x (120k/60k) = 5.77 times

In FE output, "S" curve of approximately 1.45 Vpp on the basis of Vref is obtained. The cutoff frequency of the

succeeding amplifier is 11.4 kHz.

2) Tracking Error Amplifier unit

In this sub-unit, outputs from the photo detector, namely, E and F, are processed in the differential amplifier and

further in the error amplifier, and then, (E-F) is output as TE signal from #14 pin of IC101 (TA2153FN).

Low frequency component of voltage TE is expressed as:

TE = (E-F) x 300k/100k x 82k/20k = 5.8 times

In TE output, "TE" waveform of approximately 1.51 Vpp on the basis of Vref is obtained. The cutoff frequency of the

succeeding amplifier is 20 kHz.

Fig. 2: FE circuit

Fig. 3: TE circuit

C X-97 7

3) RF Amplifier unit

Outputs from the photo detector, namely, (A+C) and (B+D), are added up, amplified and equalized in the Head

Amplifier LSI (TA2153FN). The processed-signals are output to RFI terminal as RF signals (These signals are used to

check eye patterns).

Low frequency component of voltage RFI is expressed as:

RFI = (A+B+C+D) x 5.43

RFI is used for RF Offset Control circuit. These RFI signals so output from #28 pin are AC-coupled outside the unit, and

then re-input to #27 pin and amplified by the RFAGC amplifier to obtain RFO signals.

TA2153FN has built-in function for RFAGC adjustment, as described later, and through such function, the gain of

RFAGC is controlled so that RFO output stays within 1.2 ± 0.3 Vpp range.

Also, RFO signals are used for EFM and RFAGC Adjustment circuit. They are further used to generate RFRP and RFCT

signals, both of which are used for track counting.

4) RFRP and RFCT Signal Circuit unit

RFCT signals are generated through the Head Amplifier (IC101). A RFCT signal is the difference signal that represents

the difference between the peak and bottom level of RF signal. RFRP and RFCT can be monitored at TP203 (#20 pin of

IC101, namely, TA2153FN) and TP204 (#20 pin of IC101) respectively.

Size-comparison among TE, RFRP and RFCT signals is performed by the Hysteresis Comparator in IC201 (TC9495F2),

and through such comparison, track information (TEZC and RFZC signal) is generated. Based on these signals,

information to determine tracking speed of the lens when it moves on the disk is generated. Also based on these

signals, number of tracks is counted.

Fig. 4: RF circuit

C X-97 7

5) SBAD Signal Circuit unit

In this unit, outputs from the photo detector, namely, E and F are processed through the addition amplifier. That is, E

and F are added together and (E+F) signal is output from #15 pin of IC101 (TA2153FN), as SBAD signal.

This SBAD signal, along with Focus Error signal, is used as one of the conditions that the system uses to internally

judge Focus ON/OFF based on them.

Also, SBAD signal is used to detect defects: defects that may be detected when the Pickup passes a scratch on the

disk, for instance.

Fig. 5: RFRP and RFCT circuit

Fig. 6: SBAD circuit

C X-97 7

6) APC Circuit unit

If a laser diode is driven at constant current, its optical output comes to have high level negative-characteristics, and

this may cause it out-of-control drive because of the heat. So, driving current must be controlled, through use of a

monitoring diode, so that optical output remains within the specific degree. This is exactly where APC circuit works.

LD current can be obtained by measuring the voltage between LD1 and GND. The value is approximately 35 mA at

room temperature.

Fig. 7: APC circuit

C X-97 7

1.2 SERVO DSP (TC9495F2; IC201)

1) Focus Servo system

The main equalizer of the Tracking Servo is comprised with a digital equalizer unit. Fig. 8 shows the block diagram of

the Tracking Servo.

Fig. 8: Block diagram of Focus Servo circuit

C X-97 7

A series of actions of detecting in-focus point and switching on the Focus Servo upon such detection are called "focus

search." In Focus Servo system, the system needs to move the lens to in-focus point so that it performs "Focus Close."

So, the system detects in-focus point moving the lens up and down, which it performs by changing focus search

voltage of a triangle wave. During these operations, the spindle motor maintains offset mode and keeps constant

rotating speed.

The Focus Servo is switched on through three steps shown below.

1. FOK=H

2. The Focus Error signal exceeds "Focus Standby" level threshold

3. The Focus Error signal reaches "Zero Cross"

Here are descriptions of the three steps.

While there is enough distance between the lens and the in-focus point, the system cancels SBAD offset, and defines

this level (distance) as SBOFF. Then, starting from this SBOFF standard, SBAD level moves toward FOK threshold,

reaches it, and finally exceeds the threshold. Upon this passing over the threshold, the condition of the lens becomes

FOK ="H."

As the lens moves up and down, the focus error signal changes at the in-focus point. CD-LSI (IC201) analog/digital-

converts such signal, and then, let the signal pass through the high-pass filter to remove the offset component of the

signal. The signal so processed is called FEHPF signal. When the level of the FEHPF signal (internal signal of the LSI)

exceeds "Focus Standby" level, because it means the lens has come to close to the in-focus point, the system sets the

condition of the lens to "Servo-ON Standby." Finally, the FEHPF signal matches the value of the in-focus point, and the

system triggers ON of the Focus Servo.

C X-97 7

The microcomputer monitors FOON signal while the system is performing focus search, and starts monitoring of FOK

signal from the point when 40 ms has passed after FOON signal became active (The signal is active when the

condition is "Servo ON." It shows "L" in a test with a probe). If the microcomputer judges that FOK is not active, it

performs necessary actions such as protection.

When, under Test mode, you press the Focus Close button, with the "Mode Select" of the focus set to "Display 01," you

can check Focus Error signals, search-voltage and actual actions of the lens.

Fig. 9: Focus Search Timing

+ 21 hidden pages