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6-3-4
SIGNAL
TO NOISE
RATIO
— PLAYBACK
—
Specifications:
EQ switch, CrO,/FeCr:
51 dB (min.)
NORMAL:
47 dB (min.)
CrO, tape
1. Connect the deck and the test equipments as shown in
Fig. 6-5 on page 19.
2. Load and play a TEAC MTT-150 test tape.
3. Confirm that by reproducing the 400 Hz test tone on
the tape, the output from the deck is set to the specified
output level of —5 dB (435 mV). If not, repeat the pro-
cedure in paragraph 6-3-2.
4. Change the tape to
a TEAC MTT-506 test tape com-
pletely demagnetized by a bulk tape eraser (such as the
TEAC E-2) and play it.
5. Read the indication on the AC voltmeter.
6. Compare
the output
reading to the specified output
level (—5 dB).
7. A difference of 51 dB or more is required.
FeCr and NORMAL tapes
8. Repeat the "CrO," procedure with the following sub-
stitutions.
FeCr tape
NORMAL tape
EQ switch:
FeCr position
NORMAL osition
Test Tape:
MTT-504
MTT-SO1
6-3-5
HEADPHONE
OUTPUT
LEVEL
CHECKS
—15.7 dB +2 dB (101 mV to 160 mV)
Specification:
DECK
under TEST
Fig. 6-7
Connection
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 should be —15.7 dB +2 dB (101 mV to 160 mV).
20
6-4
MONITOR
PERFORMANCE
6-4-1
MINIMUM
INPUT
LEVEL
CHECKS
Specifications:
LINE:
—19 dB £2 dB (69 mV to 109 mV)
MIC:
—67 dB +2 dB (275 pV to 436 pV)
MIC ATT:
—47 dB +2 dB (2.75 mV to 4.36 mV)
AC Voltmeter
OSCILLATOR
TEST POINT {on
DOLBY ENCODER
ATTENUATOR
DECK under TEST
T-1490
Fig. 6-8
Connection
NOTE:
To prevent
mis-measurements
for the following
procedures,
any
connection
cords
other
than
those for the respective input check must be re-
moved.
For example: Do not connect microphone cords
to the MIC jacks when checking the LINE IN in-
puts.
1. Load a blank tape.
2. Put the deck in the RECORD — PAUSE mode.
3. Set the RECORD
controls to maximum
and the IN-
PUT switch to MIC.
4. Apply a 400 Hz signal at —67 dB (346 uV) to the MIC
jacks and check for —2.5 dB +2 dB (461 mV to 731 mV)
on the AC voltmeter. (This is the minimum input level
an
check for the MIC jack — INPUT switch in MIC position).
5. Place the INPUT switch in the MIC ATT position and
check for —22.5 dB +3 dB (41.4 mV to 82.0 mV). (This
is the minimum input level check for the MIC jack — IN-
PUT switch in the MIC ATT position).
6. Place the INPUT switch in the LINE position.
7. Apply a 400 Hz signal at -—19 dB (86.9 mV) to the
LINE IN jacks and check that the AC voltmeter shows
—2.5
dB +1 dB (518 mV to 652 mV). (This is the
minimum input level check for the LINE IN inputs).
6-4-2.
SPECIFIED
RECORD
CONTROL
SETTING
Specification:
Specified input level:
—9 dB (275 mV)
8. Change the connection of the AC voltmeter to the OUT-
PUT jacks as shown in Fig. 6-9 and place the MONITOR
switch in SOURCE position.
9. Apply a 400 Hz signal at —9 dB (275 mV) to the LINE
IN jacks.
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