Marantz SD4000 - Recording Current Adjustment; MPX Filter Adjustment

6.7 RECORDING CURRENT ADJUSTMENT
SET UP
1.
Power voltage:- 50 or 60 Hz AC voltage rated for
the unit to be used in a market country.
. Input signal:- 1 kHz, 1 mV.
. TAPE SELECTOR switch position:- NORMAL.
. Load:- Measuring instrument input impedance.
.
Tape
Speed:-
1-7/8
IPS
(4.75
cm/sec)
or
3-3/4
IPS
(9.5 cm/sec).
PROCEDURES
1.
NOTES:
Stop
the
recording
bias
current
oscillation
by
dis-
connecting
the
bias
circuit.
For
example,
connect
the
base
and
emitter
of
0910
the
base
and
emitter
of
Q911.
(Complete
adjustment
as
quickly
as
possible.)
.
Set
up
the
tape
deck
to
the
normal
recording
state.
Connect
the
VTVM
across
the
10
22
resistor
con-
nected
to
the
head.
Supply
1
kHz,
1
mV
to
the
MIC
terminal.
Adjust
the
RECORD
LEVEL
control
until
the
LED
meter
indicates
OVU.
Adjust
the
variable
resistors
R111
(or
R112*)
and
R211
(or
R212*)
until
the
VTVM
reads
0.5
mV,
respectively.
.
Operate
the
oscillation
circuit.
Record
1
kHz,
1
mV
signal.
Play
back
the
recorded
signal
and
adjust
R111
(or
R112*)
and
R211
(or
R212*)
for
OVU
LED
meter
reading.
1.
Proceed
both
for
the
right
and
left
chan-
nels
in
the
same
manner.
2.
After
adjustment,
release
the
recording
bias
current.
3.
Resistors
maked
*
are
to
be
adjusted
for
3-3/4
ips
(9.5
cm/sec).
6.8 MPX FILTER ADJUSTMENT
SET UP
Power voltage:- 50 or 60 Hz AC-voltage rated for
the unit to be used in a market country.
. Input terminal:- MIC.
. TAPE SELECTOR switch:- NORMAL.
. Output terminal:- LINE OUTPUT.
. Load: Measuring instrument input impedance.
1.
PROCEDURES
1,
Connect the 19kHz, —60dB input signal to the
MIC terminal. Adjust the LINE LEVEL control for
OVU.
. Turn the MPX FILTER pushswitch to the ON
position. Adjust the L101 and L201 for minimum
output level at the LINE OUTPUT terminal.
NOTE: Proceed both for the right and left channels in
the same manner.
Mode: Record
AF OSC
TONE: 19 kHz,
CAUTIONS
1. The 19 kHz input signal should be as precise as
19+0.01 kHz.
2. If the filter characteristic is better than 30 dB, the
adjusting coil needs not to be adjusted since jt is
factory set.
15