Teac A-7300RX - Page 24

10-21
OPTIMUM
ERASURE
MEASUREMENT
Tape
SPEED
SW.
.
-
.
-
HIGH
(15
ips)
BIAS
and
EQSW
....-.------
2
—
_
Thread
the
TEAC
YTT-8003
Test
Tape
on
the
unit.
.
Apply
a
1
kHz
signal
at
10
dB
above
the
operating
level
of
—8
dB
(308
mV),
to
the
LINE
IN
jack.
_
Make
a
30
second
recording
of
the
above
signal
while
reading
and
noting
the
level
of
output,
then
rewind
to
beginning
of
this
recording.
_
Disconnect
the
1
kHz
signal
source
(AF
oscillator)
from
the LINE IN jack.
_
Connect
a
VIVM
to
the
OUTPUT
jack,
through
a
1
kHz
Narrow
Band-Pass
Filter.
_
Put
unit
in
the
Record
mode
and
“record”
(erase)
over
this
previous
recording,
then
rewind
to
beginning
again.
_
Put
unit
in
PLAY
mode
and
monitor
the
output
on
the
VTVM.
_
Difference
in
output
level,
compared
to
the
above
record-
ing
level,
should
be
more
than
65
dB.
OSCILLOSCOPE
Fig.
10-16
Test
Connections
for
Erase
measurement
10-22
CHANNEL
SEPARATION
NOTE:
Be
sure
tape
is
completely
erased
prior
to
doing
these checks.
.
Place
unit
in
Record
mode.
2.
Apply
a
1
kHz
signal
at
—8
dB
(308
mV)
to
Left
channel.
.
While
recording
measure
the
OUTPUT
on
Right
channel
with
VTVM
connected
through
a
1
kHz
band-pass
filter.
Level
shall
be
—45
dB
or
less.
.
Repeat
the
above
procedure
using
a
125
Hz
signal
and
by-passing
the
1
kHz
band
pass
filter.
.
Depress
the
STOP
button.
OSCILLOSCOPE
OSCILLATOR:
ATTENUTOR
; i under TEST
° °
SOURCE/TAPE
Te39
Fig. 10-17 Test Connections for Channel separation check
10-21 SIGNAL-TO-NOISE RATIO
—RECORD—
.
OUTPUT
and
Line
controls
should
be
at
the
specified
position.
. Set RECORD BIAS and EQ SW to 1 position.
. Remove the AF oscillator from the LINE IN jacks.
.
Place
the
unit
in
the
Record
mode
with
“no
signal”
applied.
Note
the
point
on
the
index
counter
where
re-
cording
begins.
.
Rewind
the
tape
to
the
beginning
point
and
play
it
back.
. The noise level as indicated on the VTVM should be
readings listed below.
HIGH (15 ips) ........... 48 dB
LOW (7-1/2 ips) .......... 48 dB.
10-24 DISTORTION CHECK
Tape SPEEDSW..... HIGH (15 ips)
BIAS and EQSW ............ 1
1. Thread the TEAC YTT-8013 Test Tape on the unit.
2. Apply a 1 kHz signal to LINE IN jacks.
3. Place the unit in the record mode for about 10 seconds.
Rewind and play this recorded section of the tape.
4. Read the indicated value on the distortion andyzer.
5. The distortion factor should be 0.8 % or less.
OSCILLOSCOPE
Fig. 10-18 Test Connections for Distortion cig ck
25