Sony CDP-490 - SECTION 4 ADJUSTMENTS; ELECTRICAL ADJUSTMENTS; RF LEVEL check; RF PLL Free-run Frequency Check

SECTION 3
DISSASSEMBLY OF BASE UNIT
Note:
Follow the disassembly procedure in the nomerical
order given.
@ Turn the cam to the direction of arrow (Counter
clock wise) by minus screw driver.
@ Take off the disc table.
© Remove the bracket yoke.
@ Remove the MD (BU-5BD1) to the direction of arrow.
BU-5BD1
BRACKET, YOKE
SECTION 4
ADJUSTMENTS
ELECTRICAL ADJUSTMENTS
1. Perform adjustments in the order given.
2. Use YEDS-18 (Part No. 3-702-101-01) disc unless other-
wise indicated.
3. Use the oscilloscope with more than 1OMQ impedance.
RF LEVEL check
This adjustment should be made after replacing the
Optical Pick-up Block.
Procedure:
oscilloscope
(DC range)
BD board
——
TP (RF) ©
TP (VC) ©
1. Connect oscilloscope to the test points TP (RF) and
TP (VC).
2. Turn POWER switch on.
3. Put the disc (YEDS-18) in and press > button.
4. Confirm that an optimum waveform eye pattern.
Optimum eye pattern means that shape “>” can be
clearly distinguished at the center of the waveform.
RF LEVEL VOLT/OIV : 200mV
LAKAKAAAAAAAAD i
ANY
\ AY)
0.0.04
WA
A=1.2+0.3Vp-p
E-F Balance Check
This adjustment should be made after replacing the
Optical Pick-up Block.
Procedure:
oscilloscope
(DC range)
BD board
——,
TP (TEQ) ©
TP (VC) o
1. Connect the oscilloscope to the test points TP (TEO)
and TP (VC).
2. Ground TP (ADJ), TP (TES).
3. Turn POWER switch on.
4. Put the disc (YEDS-18) in and press > button.
5. Confirm that the traverse waveform is symmetrical
above and below.
6. After adjustment, remove the TP(ADJ), TP(TES) in
ground.
NOTE: Take sweep time as !ong as
possible to obtain best waveform.
\
A
4 ov
OV B B
A=B A=B
VOLT/DIV : 1V
TIME/DIV: 1ms
RF PLL Free-run Frequency Check
Procedure:
frequency counter
main board [|
—
TP (PCK) +
1. Connect the frequency counter to the test points
TP (PCK) and TP (GND).
2. Turn POWER switch on.
3. Put the disc (YEDS-18) in and press > button.
4. Confirm that the reading on the frequency counter
is locked at 4.3218 MHz.
Focus/Tracking Gain Adjustment
A frequency response analyzer is necessary in order
to perform this adjustment exactly.
However, this gain has a margine, so even if it is
slightly off, there is no problem. Therefore, this adjust-
ment is not recomended generally to be performed.
Focus/tracking gains determine the pick-up follow-up
(vertical and horizontal) relative to mechanical noise
and mechanical shock when the 2-axis device operate.
However, as these reciprocate, the adjustment is at
the point where both are satisfied.
@ When gain is raised, the noise when the 2-axis
device operates increases.
@ When gain is lowered, it is more susceptible to
mechanical shock and skipping occurs more easily.
@ When gain adjustment is off, the symptoms below
appear.
seme
@ The tim
become
>DPLA
selectio:
pressed.
about 2
@Music d
disc con
STOP
matic q
buttons
@ Sound ig
PLAY.
display q
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2. Insert ¢
3. Connec'!
4, Adjust
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