Technics SL-PD647

SL-PD647 | SL-PD647
Mi NEW DIGITAL SERVO SYSTEM
This model employs a new digital servo circuit (super 1 chip IC: MN66271/MN662712RA). Compared to the
old digital servo circuit, the following points have been improved.
1. Reduced number of parts 3. Improved vibration resistance :
Use of a super 1 chip IC Rubber and spring 2-level floating mechanism
3 chips (MN6626, MN6650, MN6475) are reduced [fo =50 Hz (old) — 20Hz (new)]}
to a super 1 chip (MN66271/MN662712RA) 4. All adjustment VRs have been deleted for type
2. Reduced access time B.
{(old) 2.9 seconds — (new) 1.9 seconds]
Change of traverse gear
DIGITAL SERVO SYSTEM (OLD)
— 8§
Only 1 VR requires adjustment (best eye adjustment) | MN6626 MN6475 Ay
: EFM demodulation |_|pigitai|__ Digital audio
AN8800 MN6650 (Digital servo processor) Pig
1 q
A/D conversion Focus coil Lens
Focus error
output signal
Soft
microprogram
processing
Tracking
error
Traverse
coil
output signal
DIGITAL SERVO SYSTEM FOR TYPE A (NEW)
§ a MN66271 (Super 1 chip IC)
Only 1 VR requires adjustment (best eye adjustment) (Digital servo processor)
—}
= aa Digital audi \ |
PF si J=—=->! EFM —_—__ Iga ane
ae demodulation playback ———> a
AN8802 + (Digital Fitter Pa
A/D conversion Focus coil Lens
Tracking coil
Focus error
output signal
Soft
microprogram
processing
Tracking error
output signal
Traverse coil
promt te wm eee ee He ee ee ee
DIGITAL SERVO SYSTEM FOR TYPE B (NEW)
MN662712RA (Super 1 chip IC)
Adjustment
VR
has
been
deleted.
(Digital
servo
processor)
ng
ace
ee
=
eg
,
See
|
[EFM
Digital
audio
sigrial
demoduiation
playback
a
.
AN8802
Digital
Filter
-
Focus coil Lens
»
Traverse coil
A/D conversion
Focus error
output signal
Tracking coil
Soft
microprogram
processing
Tracking error
output signal
fo we ee em wm wee ewe ee ee
The following flow chart shows the sequence of automatic adjustments.
¢ Flow chart on automatic adjustment sequence
* Because the microcomputer precisely
performs automatic adjustments as shown in
the flow chart, it will take approx. 5 seconds to
finish reading TOC data if a used disc is
eccentric one or its surface is warped.
sy
Focus servo operation: ON
Tracking servo operation: ON
Temporary adjustment of tracking gain
Tracking balance adjustment
Approx. 2 sec.
No Does tracking pull in?
Yes
Fine adjustment of focus gain
Fine adjustment tracking gain
{ ‘No Does focus pull in?