Teac A-3340S - Page 30

ERASE
EFFICIENCY
—————-__
—-_.________
NOTE:
6.
7.
LEVEL VARIATION
1.
26.
3%
4,
To
measure
erase
efficiency,
a
1
kHz
band
pass
filter
(TEAC
M-206A
filter)
must
be
used.
Due
to
the
high
level
of
this,
signal,
it is
recommended
that
only
a
short
recording
be
made
(approximately
30
seconds)
to
prevent
damage
to
the
VU
meter.
RECORD
r
AMPLIFIER M-826A
fst
1 kHz
OUTPUT M-0535
Fig.
11-7
Erase
Efficiency
Check
Set-up
Apply
a
1
kHz
signal
at
0
dB
to
the
LINE
IN
jacks.
Place
the
unit
in
record
mode
and
record
this
signal.
Rewind
the
recording
to
the
beginning
and
remove
the
AF
oscil-
lator
from
the
LINE
IN
jacks.
,
Place
the
unit
in
record
mode
and
record
over
this
portion
of
tape
again.
:
-
Rewind
the
tape
to
the
starting
point
and
connect
a
Test
Set
(M+826A)}
to
the
LINE
OUT
jack
through
the
1
kHz
band
pass
filter.
‘Play the erased portion of the tape.
The
Test
Set
should
indicate
-68
dB
or
less.
Thread
a
blank
reel
of
High
Output
(SCOTCH
203),
and
select
15 ips. Set the BIAS and EQ switches to HIGH.
Record
a
variety
of
frequencies,
such
as
400
Hz,
2
kHz,
5
kHz,
8
kHz,
10
kHz,
etc.,
at
the
specified
input
setting.
-
Record
approximately
30
seconds
at
each
frequency,
During
playback,
the
output
level
should
not
vary
more
than
0.5
dB
at
400
Hz,
2
dB
at
22
kHz.
Repeat
steps
2
and
3
with
the
deck
at
7-1/2
ips.
The
tolerances
are
the
same.