Fisher AD-530 - Adjustment Procedures; Pre-Adjustment Checks & Settings; Focus, Tracking, and Diffraction Adjustments

ADJUSTMENT PROCEDURES
BEFORE CHECKING OR ADJUSTING CD PLAYER
1.
Procedures
for
all
adjustments
for
the
CD
player
from
start
to
finish
are
described
below.
2.
The
pick-up
does
not
have
to
be
adjusted
if
everything
has
been
checked
and
no
problems
were
found.
CHECKING FOCUS ERROR SIGNAL
The
effectiveness
of
the
pick-up
is
determined
by
checking
its
focus
error
signal.
This
must
be
checked
before
any
repairs
are
performed
on the
CD
player.
1...
Apply
Power
Switch
to
the
set
and
press
the
STOP
button.
2.
Cut
Main
P.C.Board
jumper
cable
J223
and
connect
an
oscilloscope
between
P202
left
terminal
and
the
GND.
(Set
the
time
at
0.5Sec/DIV.)
3. Press the OPEN/CLOSE button, place the test disc on the
table
load,
and
then
press
the
OPEN/CLOSE
button
once
again.
:
4.
Once
the
disc
is
set,
a
waveform
like
that
shown
in
the
illustration
below
will
be
repeated
three
times.
Check
that
the
p-p
voltage
of
this
waveform
is
the
same
above
and
below
the
horizontal
axis
at
3V.
Repeated three times
* p-p voltage of 3V
* + and — voltage roughly same
5. Press the OPEN/CLOSE button repeatedly to pull out and
insert the disc until the waveform appears each time the
disc is inserted and removed.
6. If the results of the above procedure are not satisfactory,
the pick-up is damaged.
7. After completing checks of the focus error signal solder
the jumper line (J223) back in place.
FREE RUN FREQUENCY ADJUSTMENT
1. Connect the frequency counter to VCO test terminal
(CN11-1) PCK test pin and to GND. (Use a 10:1 probe.)
2. Shortthe test point TP DSP OFF pin to GND.
3. Apply Power Switch to the set and press the STOP button.
4. Adjust the OSC coil T202 using a plastic screwdriver until
the frequency counter indicator reads 4.3218MHz.
SETTING OF INITIAL POSITION OF VOLUME
1. Set the variable resistors to the initial positions listed
below:
P202 (FOCUS GAIN) .........eeeeeeeeeeees Mechanical Center
P203 (E/F BALANCE) ..........ccseeeeees Mechanical Center
P204 (TRACKING GAIN) ............66 Mechanical Center
P205 (TRACKING OFFSET) ........... Mechanical Center
P206 (KICK GAIN) ....----sesseeeeeeeen sees Mechanical Center
FOCUS OFFSET ADJUSTMENT
1. Apply Power Switch to the set and press the STOP button.
2.
Connect
a
DC
Voltmeter
to
the
test
terminal
(CN9-5)
F
(focus
coil)
pin
and
short
the
focus
test
terminal
(CN10-2)
FOF
pin
to
GND.
3. In this condition check that the DC Voltmeter indicator is
in the range —0.7V ~ —1.2V.
TRACKING OFFSET ADJUSTMENT
1.
Apply
Power
Switch
to
the
set
and
press
the
STOP
button.
2.
Connect
a
DC
Voltmeter
to
the
test
terminal
(CN9-3)
T
(tracking
coil)
pin
and
short
the
focus
test
terminal
TOF
pin
to
GND.
3. ‘In this condition check that the DC Voltmeter indicator is
in the range OV+200mV, and adjust P205 if it is not.
NOTE:
Perform this adjustment once again after adjusting the
E/F BALANCE and TRACKING GAIN signals.
DIFFRACTION GRID ADJUSTMENT
This set uses a three-beam laser pick-up system. Adjusting
the diffraction grid means adjustment so that beams E and F
are in position with respect to the main beam as shown in the
diagram below on the bit streams.
The adjustment procedure involves arranging the three
beams in a straight line along the same bit stream and then
adjusting them to specified positions.
The adjustment steps are detailed below. These are very fine
adjustments so great care should be exercised in this.
DIFFRACTION GRID ADJUSTMENT
1. Apply Power Switch to the set and press the STOP button.
2. Short tester terminal (CN9-1,2) microprocessor TEST pin
to the TEST pin, and then short test terminal (CN12-1)
TOFF pin to GND to turn the tracking servo OFF.
3. In this state, connect the E-beam output of test terminal
(CN12-6) to Channel 1 of the oscilloscope and F-beam
output of test terminal (CN12-4) to Channel 2, and now
observe the lissajous waveform on the oscilloscope.