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6-4-9. ERASE EFFICIENCY
Specification: 65 dB (minimum)
Preparations:
Switch Setting:
DOLBY NR
LIMITER
BIAS
EQ
OUT
1
1
4.
5.
7.
(4)
(5)
r
Erase Efficiency Check Procedure
Fig. 6-19
30
R
3
I
A
LINE:
MIC:
NOTE
To measure erase efficiency, a 1 k z
narrow bandpass Biter should be used.
The test signal delivered from the AF
oscillator should be tuned to the filter
used.
OSCILLOSCOP E
o
£
5
Control Setting.
OUTPUT: Specified Setting (See 6-2-2)
Specified Setting (See 6-3-2)
Minimum Setting
Load
tape.
Apply and record a 1 k z signal
at +1 dB (0.869 V) for several
seconds ....................................... (I)
Rewind the tape to the mid-point
of the recording and remove the
signal from the LINE IN jacks.
(2)
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 k z signal recorded
portion ....................................... (4)
Play the tape and read the indica
tion on the VTVM to obtain the
output level of both the unerased
portion and the erased portion of
the recorded section ............... (5)
Measure the output level differ
ences between the 2 portions.
Numbers in parentheses correspond to
steps in Fig. 6-19.
a TEAC MTT-505B test
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