Panasonic RX-DT505 - Digital Servo System

RX-DT505
@ DIGITAL SERVO SYSTEM
The
newly-developed
digital
servo
system
is
adopted
in
the
servo
circuit
of
the
unit’s
CD
player
instead
of
the
ordinary
analog
servo
system.
1. The diagrams shown below represent differences between the analog servo and digital servo systems. The HEAD AMP. output signals (i.e., focus
error and tracksing error output signals) are analog. These analog signals are converted to the 8-bit digital signals through the MN6650. The
MN6650 performs the following adjustments automatically; focus offset, tracking offset, focus gain, tracking gain, and tracking balance adjustments.
The outputs from the MN6650 such as the focus coil driving signal, tracking coil driving signal, and traverse motor driving signal are converted to
analog signals again and sent to the coils and motor to perform proper servo contro! for a disc.
ANALOG SERVO SYSTEM
SY<YEOs
6 VRs require adjustment
To EMF demodulation Digital audio ep
RF signal circuit ~~ playback By
AN8374 (Analog processing)
AN8373
Vee
oy
8
es
7
Focus
coil
e
Focus error
output signal
Tracking coil
Tracking error
i}
|
output signal ,
Poses a ae Se So
DIGITAL SERVO SYSTEM
§
Only 1 VR requires adjustment (best eye adjustment) ay
. ________ToEMF demodulation__——“Cigital audio
Bpsgnel circuit playback bled
AN8800 MN6650 (Digital servo processor) i
A/D conversion
SS et es ell
Focus coil Lens
Focus error
output signal
Tracking coil
Soft
microprogram
processing
Tracking error
output signal
Traverse coil
1
1
|
1
}
1
I
|
|
i
|
'
t
'
|
'
1
1
'
i
Cette ele kee ee
Microcomputer
~ 43 -