Sony DVP-M35 / DVP-S300 / DVP-S305 / DVP-S315 / DVP-S500D / DVP-S505D / DVP-S715 Service Manual ▷ View online
– 46 –
3-3.
Servo Operation at CD and Video CD Playing
3-3-1.
Optical Pickup Control
(1) CD focus servo
Figure 3-13.
S waveform at CD disc (focus error), IC506
@§
P
The RF signal (PDI, PD2) output from the CD optical pickup is converted to the focus
error signal (CDFE, !∞P) in IC005 (CD RF amplifier CXA2555Q) of the TK-47 board.
The CD focus error signal (CDFE) is passed through the flexible flat cable and input to
the switch IC452 (MC14053) of the MB-78 board. During CD playback, it is passed
through the switch IC452, BuFF IC503, and input to @§P FE of IC506 (DSP:CXD8730R).
The focus error signal is gain-adjusted, focus bias adjusted as done during DVD playback
in the DSP.
The focus drive signal (FOUT, $§P) output from the DSP IC is input to the focus drive
IC (IC363 BA5981FP) as done during DVD playback.
IC363 is a 4ch driver IC, but performs coil driving of each pickup by switching the
level (H/L) of the MUTE terminal (9, @ºP) during CD and DVD playback.
Play mode
MUTE signal
9P
@ºP
DVD
“H”
“L”
CD, Video CD
“L”
“H”
The IC363 amplifies voltage, transforms voltage, and amplifies current, then BLT drives
the focus coil of CD pickup with its output signals (CD FCS+, CD FCS–).
– 47 –
Figure. 3-14. CD focus servo, drive
3
4
12
13
5
15
32
3
4
3
13
14
14
28
28
Optical Block
PD1
PD2
29
6
CDFE
CN005
CN452
IC005 CXA2555Q
MB-78 board
TK-47 board
CDRFDC
6
15
15
29
ZIF
CN001
IC452
MC14053
IC503 (BUFF)
IC506 (DSP)
route is the same as
the DVD focus servo
IC363
BA5981
DRIVE
CD FCS+
To CD focus coil
CD FCS–
– 48 –
(2) CD tracking servo
Figure 3-15.
CD tracking servo
Figure 3-16.
Trv (TE at tracking servo OFF)
waveform at CD disc,
IC506
@¢
P
Figure 3-17.
TE (enlarged Trv) waveform
at CD disc, IC506
@¢
P
Figure 3-18.
1TJ (track jump) waveform at
CD disc, IC506
@¢
P
CDTRK–
To CD pickup
tracking coil
tracking coil
CDTRK+
TOUT
TE
5
27
20
IC005
CXA2555Q
TK-47 board
CDE
CDTE
TEATT
From
optical
block
optical
block
CDF
13
12
AMP
6
1
IC452
MC14053
IC506
CXD8730
IC503
NJM3403
DSP
AMP
IC363
BA5981
Tracking
Drive
MB-78 board
15
6
7
14
13
2
24
6
49
12
11
11
12
– 49 –
The CDE and CDF signals output from the CD optical pickup are converted to the CD
tracking error signal (CDTE !£P) at IC005 of (CXA2555Q) the TK-47 board.
The CDTE signal is input to the switch IC (IC452, MC14053) of the MB-78 board.
During CD playback, it is passed through the switch IC (IC452), amplified at IC503,
and input to @¢P TE of IC506 (DSP CXD8730R).
Like DVD playback, the tracking error signal is gain-adjusted, tracking bias-adjusted,
and tracking auto level-adjusted in the DSP.
The DSP tracking drive signal (T OUT $ªP) is voltage-amplified, voltage-converted,
and current-amplified by the IC (IC363 BA5981) for tracking driving, and used to
drive the CD pickup tracking coil.
Track jump control during CD search is carried out by IC506 (DSP CXD8730R) as
done during DVD search.
As a result, when performing 1 track jump or N track jump (many track jumps), tracking
pulses are generated, the tracking zero cross timing is detected, tracking brake is
controlled, and the number of track jumps is measured.
* Tracking auto level adjustment.
This function operates only during CD and V-CD playback.When the TE level (traverse
waveform) is small due to the inconsistency of the disc, this level adjustment is
performed to eliminate the inconsistencies. Consequently, like gain adjustment, the
adjustment is performed each time the disc is replaced (tray is opened), to set the
traverse level to 2.0 Vp-p.
After setting the disc and turning ON the focus servo, the peak-to-peak value of the TE
signal (this TE signal is called the traverse signal) is measured by the IC506
(DSP:CXD8730R).
The measurement results are read by the IC805 (system control IC) to determine the
gain variable amount. The response (variable amount) is then returned again to IC506
(DSP:CXD8730R).
Upon receiving this, IC506 outputs control signal for the tracking auto level adjustment
from !¡P and !™P of the IC506 (DSP:CXD8730R). It is added by IC503 and converted
to the analog voltage (TEATT signal).
The TEATT signal is input to !™P of IC005 (CXA2555) of the
TK-47 board, and gain-controlled inside the IC. The variable width is about ±3.0 dB.
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