Technics SL-P202A - Page 42

|
S.°202._
3-2 TDA8809 RADIAL ERROR PROCESSOR
TDA8809
Gain Control
Circuit
Circuit <<]
A
£_ 30
Radiat 9
Input Mirror
Rel Rel Re2 Re2
2 2 4
Rel + Re2 ‘
Radial Motor
2 Current Selector for
Optical Arm (4 bit Data)
eThe resistor R3535 sets the amount of 1/4 track pitch due to the sinusoidal
output
current
of
the
DAC
signal.
form
of
the
radial
error
signal.
By
means of TL and RE dig the hold range
e i the
TNE
SOVHEY
sCempOnEnUS,
“SeEt
ine
is
extended
to
3/4
track
pitch.
oscillator frequency are R3530, R3531,
C2530, C2531. eFor high speed track crossing, four
dived RE dig signal is given by
eT i - dt trol
De
SADOES:
BO
Po
ate
URee
orcontre
pulling
Div
4
input
to
low
level.
the operations which have to be
performed by the radial error
processor.
3-2-1 Radial processing
;
The
radial
error
processor
has_
to
eThe
DAC
output
is
a
current
source
process
the
basic
input
signals
RE1
output
used
to
move
the
radial
arm.
and
RE2
and
to
generate
the
full
The
normal
control
is
RE,
but
to
jump
radial
error
signal
RE.
The
RE
signal
beyond
tracks
and
to
compensate
bumps
is
the
basic
signal
to
keep
the
reading
the
DAC
signal
is
used.
beam
on
track.
eThe
RE
lag
output
gives
the
loop
a
more
powerful
control.
This
output
is
only
activated
during
normal
playback.
RE1 and RE2 are caused by more or less
light of the laser failing onto diodes
D1, D2 or D3, D4 (see figure below)
RADIAL
eThe RE dig is a 11-bit quantized TRACKING
version
of
the
RE
signal.
The
function
BEAM
Pe
Th
Di
ieee
of
RE
dig
is
not
in
all
sets
the
same.
=
5
D2
Below is the function in a audio _ at TRESS OEE te Rely
player explained. If a TL occurs the = oP 1@ | L® |
microprocessor looks to RE dig, the - ON TRACK D3
value of RE dig indicates whether the =e, =o: LM)
microprocessor has to compensate for a TRACK SHIFTS RIGHT
right or left bump via DAC . The
maximum hold range of RE is normally RE1 = i14+i2 and RE2 = i344
LF. SIGNALS
D1+D2+D3+D4
Behe we ieee