Fisher MC-715 - RECOMMENDED TEST EQUIPMENTS; AM TUNER ALIGNMENT

RECOMMENDED TEST EQUIPMENTS
The
following
test
equipments
are
recommended
to
completely
test
and
align
the
Tuner:
e FM Standerd Signal Generator Line Voltage Isolation Transformer
_-
(87.5
~
108MHz
20~120dBy
/750]
Accurately
Calibrated
AC
Voltmeter
e
AM
Standerd
Signal
Generator
AM
Test
Loop
Antenna
~[520~1710kHz
20~130dBz
/500]
AM
Dummy
Antenna
e FM Stereo Standerd Signal Generator
{20 —1k—15kHz Main 90% Pilot 9%]
e Radio IF Generator Scope
[450kHz + 10kHz 10.7MHz=+ 0.3MHz]
e DC Voltmeter [Hight Impedance 1MQ]
FM Dummy Antenna [759 — 3000 Balanced Type]
Distortion Meter
Oscilloscope
AM TUNER ALIGNMENT oe
AM
ALIGNMENT
—
FUNCTION
switch
to
AM
position.
Perform
this
alignment
after
Maintain
generator
output
as
low
as
possible
for
suitable
indication.
FM
Tuner
Alignment.
Standard test frequency 1kHz and Modulation 30% at AM
GENERATOR DIAL SETTING INDICATOR PROCEDURE
Connect
455kHz
Radio
Connect
Radio
IF
|
Adjust
AM
IFT
(T4)
for
maximum
IF
Genescope
output
Genescope
input
gain
and
best
symmetry.
to
|C4
(Pin
No.1)
and
to
TP2
and
ground
|
Keep
signal
low
enough
for
noise
ground
terminal.
terminal.
on
responce.
Use
100pF
Capacitor
in
series
with
generator
output
lead.
Position of
non-interference
Minimum
Frequency.
1. AMIF
ALIGNMENT
Adjust AM DET Coil (T6) for
maximum gain output.
Center of 515kHz
calibration mark
on dial.
Connect AC VTVM
and Oscilloscope
to TP2 and ground
terminal.
Connect Standard Loop
Antenna to output
terminal of AM RF Signal
Generator. Place Loop
Antenna 60cm away from
Loop Antenna of MC-715.
Generator setting to
515kHz.
Modulate with 1kHz
(30% modulation).
Adjust AM OSC Coil (T5) and
AM ANT Coil (T3) for maximum
gain output.
2. AM RF
TRACKING
ALIGNMENT
(51 5kHz)
Center of 1670kHz
calibration mark
on dial.
Adjust AM OSC Trimmer (TC4)
and AM ANT Trimmer (TC8) for
best curve form and maximum
deflection. an.
Change generator Same as above.
setting to 1670KHz.
3.
(1670kHz)
Note:
Repeat
Items
2
and
3,
and
confirm
that
Tracking
Error
is
minimized
and
best
sensitivity
is
obtained
at
each
frequency
point.
Then,
set
generator
to
1000kHz
and
confirm
that
the
pointer
is
correctly
set
on
the
dial
plate.
Use
ascrewdriver
with
plastic
grip
for
all
adjustments.
CAUTION
.
This
precision
high-fidelity
instrument
should
be
serviced
only
by
qualified
personnel,
trained
in
the
repair
of
transistor
equipment
and
printed
circuitry.
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