Technics SL-P250 - Page 10

PLL ADJUSMENT
1.Connect CH1 of the oscilloscope to the LINE OUT
terminal (either of Lch or Rch) and ground.
Oscilloscope setting: VOLT
2.Set the test disc (SZZP1054C) and turn ON the power
switch of the player. (Refer to page 13.)
3.Play Track No.6 (wedge 0.7mm) of the test disc.
4.Check the waveform displayed on the oscilloscope and
adjust VR501 in the following steps.
Step 1.Turn VR501 clockwise slowly and observe the
point at which the waveform on the oscilloscope
begins to be disturbed.
Step 2.Turn VR501 counterclockwise slowly and observe
the point at which the waveform on _ the
oscilloscope begins to be disturbed.
Step 3.Set VR501 in the middle between the points
observed in the above steps ” 1” and” 2”
Noise started to appear in output sound with
_’ VR501 turned counterclockwise.
Final setting point.
‘\ Noise started to appear in output sound with
VR501 turned clockwise.
CHECK OF PLAY OPERATION AFTER ADJUSTMENT
Check of skip search
1.Play an ordinary disc.
2.Press the skip button and verify skip search operation
(forward and reverse).
Check of manual search
1.Play an ordinary disc.
2.Press the manual search button and verify that smooth
manual search can be performed at low and high speeds
(forward and reverse).
OPTICAL PICKUP ADJUSTMENT
Measuring Instruments and Special Tools
@ Tow-channel oscilloscope (with trigger)
of 30MHz or over
@ Test discs
Test disc (SZZP1014F) old or new type
Inspection test disc (SZZP1054C)
Unevendisc (SZZP1056C)
Adjustment Procedure’
@ if the optical pickup and spindle motor are replaced ,
adjust itaccording to the following procedure.
Step 1:Make the temporary of
each VR. (Refer to page 15.)
Step 2Turntabie height adjustment.
(Refer to page 18.)
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Check of playability
1.Play the test disc (SZZP1054C).
2.Play
the
track
No.6
(wedge
0.7mm)
and
verify
that
there
is
no skip
sound
or
noise.
3.Play
the
track
No.13
(black
dot
0.7mm)
and
verify
that
there
is
no
skip
sound
or
noise.
@ Hexagonal wrench (2.0mm)
@Screw lock paint (RZZ0L01)
@ Hexagonal wrench (1.27mm)
@Feeler gauge (RZZ0297)
@Filter (Refer to page 13)
Step 3:Mechanical adjustment.
(Refer to page 18.)
Step 4:Electrical adjustment.
(Refer to page 14.)
TURNTABLE HEIGHT ADJUSTMENT
1.Connect
CH1
of
the
oscilloscope
to
FEG
(+)
and
GND
Adjust
the
turntable
height
as
follow:
(-)
of
the
servo
P.C.B.through
the
filter.(Refer
to
page
A.Insert
the
0.9mm
feeler
gauge
(RZZ0297)
as
shown
41.)
below.
Oscilloscope setting:VOLLT.........
0.9 mm feeler
gauge (RZZ0297)
2.Set the oscilloscope to DC zero balance.
3.Set
a
test
disc
(SZZP1014F
or
SZZP1054C
and
turn
ON
the
power
switch
of
the
player.
(Refer
to
page
13.)
4.Set the player to the play mode.
5.Measure
the
DC
level
(AmV)
displayed
on
the
oscilloscope.
@lf
the
value
of
A
is
within
the
range
of
+
60mvV
,
the
turntable
height
is
correct.
If
it
is
not
within
this
range
,
make
the
necessary
adjustments
using
the
0.9mm
feeler
gauge
(RZZ0297).
If Ais more than +60mvV , make the turntable lower.
if
Ais
less
than
-60mV
,
make
the
turntable
higher.
B.Loosen the turntable set-screw.
C.Adjust
turntable
height
to
0.9mm
with
the
feeler
gauge
as
shown
above.
D.Tighten
the
turntable
set-screw
by
using
the
1.27mm
hexagonal
wrench.
E.Check
the
turntable
height
adjustment
by
following
steps 1 ~ 5 above.
MECHANICAL ADJUSTMENT
1.Connect
CH1
of
the
oscilloscope
to
TJ101
(+)
and
GND
(-)
of the
servo
P.C.B.
Oscilloscope
setting:VOLT........
200mV
SWEEP.....0.5usec.
4.Monitoring RF signal on the oscilloscope, adjust the two
adjusting screws alternatelywith the 2.0m™m hexagonal
wrench so that the vertical fluctuation of RF signal is
minimized and the eye pattern is most stretched.
5.Turn OFF the power switch of the player.
6.After the adjustment, apply screw lock paint(RZZOL01)
to the adjusting screws.
2.Set
the
test
disc
(SZZP1056C)
and
turn
ON
the
power
swith
of
the
player.
(Refer
to
page
13.)
3.Using
the
manual
search
buttons
,
move
the
pickup
so
that
the
mechanical
adjustment
screws
line
up
with
the
adjustment holes in the bottom panel.
Pick-up | Sea
sil
{
Note:The
mechanical
adjustment
screws
have
been
already
locked
with
screw
lock
paint
at
the
factory.
It
might
be
hard
to
turn
them.
SN
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Mechanical adjustment screws