SECTION 2
ELECTRICAL ADJUSTMENTS
1.
Perform adjustments in the order given.
2.
Use YEDS-18 disc
(3-702-101-01)
unless otherwise indicat-
ed.
3.
Use the oscilloscope with more than l0MO impedance.
RF
Level Check
Procedure:
BD
board
,..-'-,
TP
(RF)
TP
(VC)
oscilloscope
(DC
range)
-~
:=t;_J
1.
Connect oscilloscope to test point
TP
(RF) and
TP
(VC)
on
BD
board.
2.
Confirm
that
RF
level and eye pattern is optimum.
Oputimum eye
pattern
means
that
shape
"◊"
can be
· clearly distinguished
at
the center of the wave form.
RF
signal Reference Waveform (eye pattern)
RF
leve
VOLT/DIV:
200mV
TIME/DIV:
SOOnS
~------T
A
~.,,,._,,.,_,,._
l
1.2±0.3Vp-p
1 REFERENCE 1
E-F
Balance Check
Procedure:
oscil/oscope
(DC
range)
~
:l~I
TP
(TE
0)
o +
TP
(VC)
o -
1.
Connect test point
TP
(ADJ) and
TP
(TES) to ground
with lead wire.
2.
Connect oscilloscope to test point
TP
(TE
0)
and
TP
(VC)
on
BD
board.
3.
Turn
POWER switch on.
4.
Put
disc (YEDS-18) in and play back.
5.
Confirm
that
the oscilloscope waveform is symmetrical
on the top and bottom in relation to
0V.
6.
After check, remove the lead wire connected in step
1.
Note :
Take
sweep time
as
long as possible to obtain best
waveform.
A=B
A=B
-4-
RF
PLL
Free-run Frequency Check
Procedure:
Mainboard
,..-'-,
TP
(PCK)
frequency
counter
i
1
1
1.
Turn
POWER switch
on.
2.
Put
disc
(YEDS-18)
in
and play back.
3.
Confirm
that
reading on frequency counter is 4.3218MHz.
Focus/Tracking Gain Adjustment
A frequency responce analyzer is necessary in order to
perform this adjustment exactly.
However, this gain cas a margin, so even if it is slightly off.
there is no problem. Therefore, do not perform this adjust-
ment.
Focus/tracking gain determines the pick-up follow-up (ver-
tical and horizontal) relative to mechanical noise and
me-
chanical shock when the 2-axis device operate.
However, as these reciprocate, the adjustment is the point
where both are satisfied.
• When gain is raised, the noise when the 2-axis device
operates increases.
• When gain is lowered, mechanical shock and skipping
occurs more easily.
• When gain adjustment is off, the symptoms below appear.
~
Focus
Tracking
s
•
The
time until music
starts
becmes longer for
STOP
-
t>
PLA Y or automatic selection.
low
low or high
(!<III
◄
,
►
IJl,,,,I
buttons
pressed.)
(N
ormally
takes
about 1 sec-
onds.)
• M usic does not
start
and disc
continues to rotate for
STOP
-
t>
PLA Y or automatic selec-
-
low
tion.
(!<III
◄
,
►
IJl,,,,I
buttons. pressed.)
• Sound
is interrupted during
PLA
Y.
Or time counter display
-
low
stops progressing.
•
More
noise
during 2-axis
high high
device operation.
The
following is a simple adjustment method.
-Primary
Adjustment-
Note : Since
exact
adjustment cannot be performed,
remember the positions of the controls before perfor-
ming the adjustment.
lf
the positions after the primary adjustment are
only a little different, returs the controls the original
position.
oscil/oscope
(DC
range)
BDboard~
TPlfE01••r
,~
TP
(TE
0)
o..-.1 -
TP
(VC)
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