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SECTION
3
ELECTRICAL BLOCK CHECKING
Note:
as
CD
Block
basically
constructed
to
operate
without
adjustment.
Therefore, check each item in order given.
2.
Use
YEDS-18
disc (3-702-101-01)
unless
otherwise
indicated.
3.
Use the oscilloscope with more
than 10M 22 impedance.
A,
Clean
an
object
lens
by
an
applicator
with
neutral
detergent
when
the signal level is low
than
specified
value
with the following
checks.
S- Curve Check
oscilloscope
BD
board
poe
TP (FEO)
eae We er
TP (VC)
o~=——o
—-
Procedure:
1.
Connect
oscilloscope
to test
point
TP
(FE)
on
BD
board.
2.
Connect between test point TP (FEI) and TP (VC) by
lead wire.
.
3.
Turned Power switch on and actuate the focus search.
(actuate the focus search when disc table is moving in
and out.)
4.
Check
the
oscilloscope
waveform
(S- curve)
is
symmetrical between
A and
B.
And
confirm
peak
to
peak level within
3+1Vp-p.
S-curve
waveform
symmetry
within 3+ 1Vp-p
5.
After check, remove
the lead wire connected in step 2.
Note :
* Try to measure
several times to make
sure that
the ratio of
A:B or B:A
is more
than
10:7,
* Take sweep
time as long as possible and light up
the brightness
to obtain
best waveform.
RF Level Check
oscilloscope .
BD
board
fy
TP
CRFO)
cee
te
TP
(VC)
o_o
-—
Procedure:
1.
Connect
oscilloscope
to test
point
TP
(RFO)
on
BD
board.
2.
Turn Power
switch on.
3.
Put disc (YEDS-18)
in and playback.
4.
Confirm that oscilloscope waveform
is clear and check
RF
signal level is correct
or not.
Note:
Clear RF
signal waveform
means
that the shape
"©"
can be clearly distinguished at the center of
the waveform.
VOLT/DIV : 200mV
TIME/ DIV : 500nS
level : 1.24938Vp-p
on TAN
9,9,
AREER
HAAR
(>
E-F Balance Check
oscilloscope
BD board
ea tamee
TP CTE)
TP (VC)
O«——o +
o~i——O —
Procedure:
1.
Connect test point TP (ADJ) to ground and TP (TEI)
to TP (VC) with lead wire.
Connect
oscilloscope
to test
point
TP
(TE)
on
BD
board.
Turn Power switch on.
Put disc (YEDS-18) in and playback.
Confirm that the oscilloscope waveform is symmetrical
on the top and bottom in relation to OV, and check this
level,
Traverse
waveform
level:
2+1Vp-p
6.
Remove
the lead wire connected
in step
1.
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