Teac A-450 - ERASE EFFICIENCY

Fe-Cr TAPE
7.
Repeat
the
above
procedure,
except
use
the
TEAC.
MTT-5O04T
test
tape
and
set
BIAS/EQ
switches
to
“2”
position.
The
VIVM
should
indicate
—50
dB
minimum
(2.44
mV
maximum).
This
—50
dB
corresponds
to
the
specified
signal-to-
noise
ratio
of
45
dB
(minimum):
the
difference
between
the
residual
noise
of
—50
dB
and
the
specified
output
level
—5
dB.
7-3-7.
ERASE
EFFICIENCY
To measure erase efficiency, a 1 kHz
narrow bandpass filter should be used.
The test signal delivered from the AF
oscillator should be tuned to the filter
used.
CrO, TAPE
1.
2.
CONNECTION
NOTE
Load a TEAC MTT-505TB test
tape.
Apply and record a 1 kHz signal
at +5 dB (1.37 V) for several
seconds, .........+-0+- (1)
Rewind the tape to the mid-point
of the recording and remove the
signal from the LINE IN jacks.
Place the deck in the record mode
and record through this previously
recorded portion with no input
signal applied. .......... (3)
Rewind the tape to the starting
point of the 1 kHz signal recorded
portion.
Play the tape and read the indica-
tion on the VIVM to obtain the
output level of both the unerased
portion
and
the
erased
portion
of
(2)
the recorded section. ...... (5)
Measure the output level differ-
ences between the 2 portions.
record
(3)
Specification: 65 dB (minimum)
Fe-Cr & Hi-Fi TAPES
The erase efficiency checks for these
tapes usually may be omitted unless
the technician wants to confirm they
also are within specifications.
Hi-Fi TAPE
10.
11.
12.
Repeat
the
above
“‘CrO,
Tape”
procedure,
except
use
the
TEAC
MTT-501
test
tape
and
set
BIAS/EQ
switches
to
“3”
position.
The
VTVM
should
indicate
—50
dB
minimum.
This
—50
dB
corresponds
to
the
specified
signal-to-
noise
ratio
of
45
dB
(minimum):
the
difference
between
the
residual
noise
of
—50
dB
and
the
specified
output
level
—5
dB.
OSCILLOSCOPE
DECK
under TEST
Fig. 7-18 Connection
SWITCH & CONTROL SETTING:
4 i :
OLBY eval
rea / COPY ~ SOURCE
Controls are same as
preceding section.
rewind
(4)
(5)
Fig. 7-19 Erase Efficiency Check Procedure
25