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SECTION
3
ELECTRICAL BLOCK CHECKING
Note:
1.
CD Block basically constructed
to operate with-
out
adjustment.
Therefore,
check
each
item
in
order given.
Use YEDS-18 disc (3-702-101-01) unless otherwise
indicated.
to
3.
Use the oscilloscope
with
more
than
10M
im-
pedance.
4.
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
—>
_ |C)
TP (FEO) o=—lo>
TP (VC)
O—#t——-o -
Procedure:
1.
Connect
oscilloscope
to test point TP (FE) on
BD board.
2.
Connect between
test point TP (FE1) and TP
(VC) by lead wire
3.
Turned
Power
switch
on and actuate
the focus
serch. (actuate the focus serch 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 341Vp-p.
S curve waveform
symmetry
within 31Vp-p
5.
After check, remove
the lead wire connected
in
step 2.
Note:
* Try to mesure
several
times
to make
sure
that the ratio of
A: Bor 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
ata: |
TP (RFO)O——° +
TP (VC)
O=t—(0-
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 wave-
form.
VOLT/DIV
:200mV
RF signal waveform
TIME/DIV : 500nS
RR
YAN
ea
(Y\
ANAM
E-F Balance Check
ANN
A)
level :
1.294 VPP
oscilloscope
BD
board
—
|O)
TP (TE)
O«— oF
TP (VC)
ow—tlo-
Procedure:
1.
Connect test point TP (ADJ) to ground and TP
(TEI) to TP (VC) with
lead wire.
3.
Turn Power switch on.
4,
Put disc (YEDS-18) in and playback.
5.
Confirm
that
the osilloscope
waveform
is sym-
metrical on the top and bottom in relation to OV,
and check this level.
Traverse oscilloscope
symmetry
level: 21Vp-p
6.
Remove the lead wire connected in step 1.
—7—
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