Teac A-300 - Electrical Checks and Adjustments (Continued); Signal-to-Noise Ratio, Headphone Output, and Monitor Performance

6-1-5.
SIGNAL
TO
NOISE
RATIO
-PLAYBACK—
Specification:
47
dB
(min.)
1.
Place
the
deck
in
the
PLAY
PAUSE
mode
with
no
tape
loaded,
2.
Read
the
indication
on
the
AC
Voltmeter.
3.
Compare
this
reading
to
the
specified
output
level
of
—5
dB
(436
mV).
The
difference
shall
be
47
dB
or
more.
;
6-1-6.
HEADPHONE
OUTPUT
LEVEL
CHECKS
Specification:
—21
dB
+
3
dB
(48.9
mV
to
97.5
mV)
NOTE:
An
8
ohm
non-inductive
resistor
should
be
used
as
the
test
load
resistor.
1.
Load
and
play
a
TEAC
MTT-150
test
tape.
2.
Measure
the
level
across
the
test
load
resistor.
3.
Level
shall
be
-21
dB
+
3
dB
(48.9
mV
to
97.5
mV).
6-2. MONITOR PERFORMANCE
6-2-1.
MINIMUM
INPUT
LEVEL
CHECKS
Specifications:
LINE:
—19dB+3
dB
(61.5
mV
to
123
mV)
MIC:
—67dB+3
dB
(245
uV
to
489
uV)
DIN:
—35dB+3
dB
(9.75
mV
to
19.5
mV)
NOTE:
To
prevent
mis-measurements
for
the
following
procedures,
any
connection
cords
other
than
these
for
the
respective
input
check
must
be
removed.
For
example:
Do
not
connect
the
Microphone
and
the
DIN
cords
to
respective
input
jacks
when
checking
for
the
LINE
inputs.
1. Load any recordable tape.
2. Place the deck in the REC PAUSE model.
3. Set the LINE controls to maximum.
Preparations:
Connection: See Fig. 6-5.
Switch Setting:
[=
[orman|
our
[rare
_|
Control Setting:
OUTPUT:
Specified
Setting
(See
6-1-2)
MIC, LINE: Minimum
Preparations:
DECK
under
TEST
PHONES
TEST LOAD RESISTORS:
Fig. 6-7 Connection
Switch Setting:
BIAS
DOLBY
NR
|
MONITOR
——PNorwa
[our
[Tare
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
MIC, LINE: Minimum
Preparations: AC Voltmeter
OSCILLATOR
DECK under TEST
Fig. 6-8 Connection
Switch
Setting:
DOLBY NR | MONITOR
Control Setting:
OUTPUT: Specified Setting (See 6-1-2)
MIC, LINE: Minimum
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