Electrical Adjustments - Pioneer LD-700/KU Service Manual

LD-700/KU
3.
ELECTRICAL
ADJUSTMENTS
Instruments and tools used:
• Color monitor
TV
• Stereo
system
• Dual
trace oscilloscope (with
time delay sweep,
DC-35MHz)
•
Audio
SG
• Frequency counter
• Shorting clips
•
Test disc
B1
(or
FI
•
CU-700
Precautions:
•
Confirm
that
all
power
supply voltages are
correct.
©
Confirm
that there are
no
mechanical problems.
• Pinion adjustment of the
slider
potentiometer
must be completed.
• All parts of the pickup except the
grating
must
be correctly adjusted.
Use FI
test disc for
the
grating adjustment.
•
The
oscilloscope range
figures
here assume the
use of a 1:1 probe.
•
Do
not
insert
and remove
discs
when
the player
is
on
its
side up. (Do not press
then
/A button
on
the player.)
Preparations:
• Connect
a
monitor
TV
and
stereo
amp
to the
player.
•
Remove
the top and bottom
panels.
•
Insert
a
test disc.
•
Perform
PREB, SRVB
and
DEMB
adjustments
with the
player standing on
its right side.
• Perform the
PREB
adjustment with
the
SRVB
and
DEMB
boards open (remove
the
SRVB
and
DEMB
board
screws).
vr
1
VR
2
VR
3
VR4
VR
5
RF LEVEL
FOCS OFFSET
FOCS
GAIN
TRKG BAL
TRKG
GAIN
PREB
adjustment
points
TP
9
-11V
+
1 !
V
G
N
D
B
1
B4
B 2
B 3
B1FB3
RF
FOCS A-
FOCS
ERROR
TRKG
GAIN MON.
TRKG
OSC
IN
+11 V
APC
VCC
GNO
OSCILLOSCOPE
TEST
POINT
ADJUST-
MENT
POINT
CHECK
POINT/
ADJUST-
MENT
STANDARD
ADJUSTMENT PROCEDURE
PREB ADJUSTMENT
On PREB
unless
otherwise
specified.
TP7
TP8
On PREB
unless
otherwise
specified.
0.25V
-
0.5V
5mV/div
0.2V/div
O.lmS/div.
5mS/div
Positive
amplitude
=
Negative
amplitude
Always
perform the following adjustments
after
replacing, repairing or adjusting the pickup
or
replacing
PREB.
CONFIRMATION OF THE
LD POWER
• Measure
the voltage between
TP7
and TP8.
•
Verify the
voltage
is
in the range of 0.25V to 0.5V.
If
not, replace the pickup.
FOCS OFFSET ADJUSTMENT
•
Adjust the
DC
voltage of
TP3
so that
it is
0V±5mV
when
the
player
is
in
the standby mode.
TRKG BALANCE ADJUSTMENT
•.
Use search to
locate
frame #20,000.
• Open
the
TRKG
loop. (Connect pins 20 and 22 of
SRVB
Z401 PM4001
using the shorting
clips.)
• Adjust so
that the positive and negative
sides of the
tracking
error
wave
are equal.
3-2
©