Erase Efficiency; Channel Separation; 13 6-6-9 Adjacent Track Crosstalk Measurement - Teac C-1 Service Manual

6-6-7 ERASE EFFICIENCY
Specification:
65 dB (min.)
OSCILLOSCOPE
°
AMP SPKR
y=
OSCILLATOR
7 Oe
0 Oe 000
Fig. 6-17 Connection
NOTE: To measure erase efficiency, a 1 kHz narrow band-
pass filter should be used. The test signal delivered
from the AF oscillator should be tuned to the filter
used.
Numbers in parentheses correspond to steps in Fig. 6-18.
1.
2'
24
Load a TEAC MTT-506 test tape.
Apply and record a 1 kHz signal at +1 dB (0.869 V,
saturation level) for several seconds ........... (1)
. 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, sey eee oS TN ei ele tines ole eal ye (3)
. Rewind the tape to the starting point of the 1 kHz signal
recorded portion .............02 000-00 ee (4)
. Play the tape and read the indication on the AC volt-
meter to obtain the output level of both the unerased
portion and the erased portion of the recorded section
nai Lenten td cd giatdtia ies Wt aoe Reds e B-8, Bee a aren tl. aah (5)
. Measure the output level differences between the 2 por-
tions.
record =
eS IR
a amen 1
_rewind um
\ \
s sR
erased ona,
C rR :
rewind Feed
—_
EEEEESR
ms aeaces 2BS
C3 Erased
1-465
Fig. 6-18 Erase efficienty check procedure
6-6-8 CHANNEL SEPARATION
Specification: 35 dB (min.)
OSCILLOSCOPE
°
AMP SPKR
e¢
@ ©
[ee
AC Voltmeter
OSCILLATOR
0@@.,,
DECK
under TEST
ATTENUATOR
LINE IN
L
ouTPuT IkHz FILTER
Fig. 6-19 Connection
NOTE: To check channel separation (cross talk between
channels), a 1 kHz narrow bandpass filter should
be used. The test signal delivered from an AF oscil-
lator should be tuned to the filter used.
Numbers in parentheses correspond to steps in Fig. 6-20.
1. Load a TEAC MTT-506 test tape.
2. Apply a 1 kHz test-tone at —9 dB (274 mV) into the left
channel.
3. Place the deck in the record mode for about 30 sec-
CONGSS 3. c05 Sys Sa ee Nee wigs wi bl nets ate Ba Oe oy (1)
4. Rewind the tape to the starting point of recording.
RES AO toi tra lee dete Bla Mera na Pa tent Gob ag WRB a nests (2)
5. Play the tape and measure the output level differences
between the left and right channels............ (3)
record —_
a) f oe IE |
rewind fam
\
(2) ¢ C= = ome
play and compore ami
GERBD Signal
{3) C eee C= Blonk
1-467
Fig. 6-20 Channel separation check procedure
6-6-9 ADJACENT TRACK CROSSTALK
MEASUREMENT
Specification: 40 dB (min.)
OSCILLOSCOPE
AMP. SPKR
OSCILLATOR
AC Voltmeter
DECK
under TEST
ATTENUATOR iwici
1 Se3-1
Fig. 6-21 Connection