Electrical Block Checking; S Curve Check; Rf Level Check; E-F Balance Check - Sony CDP-791 Service Manual

SECTION
3
ELECTRICAL
BLOCK
CHECKING
CDP-791/X1
1
1ES
Note
:
1.
CD
Block
basically
constructed
to
operate
with-
out 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
10MJ?
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.
RF
Level
Check
S
Curve Check
BD
board
TP
(FEO)
TP
(VC)
oscilloscope
JP
Procedure
:
1
1
1.
Connect
oscilloscope to test point
TP
(FEO)
on
BD
board.
2.
Connect between
test
point
TP
(FES) 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
3±lVp-p.
S curve
waveform
symmetry
within
3±lVp-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
:
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.
BO
board
Tp"(RF)
O
TP
(VC)
O
oscilloscope
-P
Procedure
:
1.
Connect
oscilloscope to
test
point
TP
(RF) 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
"0"
can be
^clearly distinguished at the center
of
the
wave-
form.
RF
signal
waveform
VOLT/DIV
:
200mV
TIME/DIV
:500nS
T
level
:
v
p-p
E-F Balance
Check
BD
board
oscilloscope
TP
(TEO)
TP
(VC)
Procedure
:
1.
Connect
test
point
TP
(ADJ)
to
ground
and
TP
(TES)
to
TP
(VC)
with
lead
wire.
2.
Connect
oscilloscope to
test
point
TP
(TEO)
on
BD
board.
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
0V,
and
check
this
level;
Traverse
oscilloscope
,v
—
drntewfHr
—
—
L
symmetry
level:
2±lVp-p
6.
Remove
the lead wire connected
in
step
1.
-
5
-