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RS-B25
7. Place UNIT into CrO, tape mode.
8. Change
test
tape
to CrO,
reference
blank
test
tape
(QZZCRX), and record 1kHz, 50Hz, 100Hz, 200Hz, 500 Hz,
4kHz, 8kHz, 10kHz and 15kHz signals.
Then, playback
the signals and check
if the curve
is within the limits
shown
in the overall frequency response chart for CrO,
tapes (fig. 14).
an
9. Place UNIT into metal tape mode and change test tape to
metal
reference
blank
test tape (QZZCRZ),
and
record
+50B
a
1kHz,
50Hz,
100Hz,
200Hz,
500Hz,
4kHz, 8kHz,
10kHz,
iin
12.5kHz and 15kHz signals.
Then, playback the signals
|
Eile iil
TH
and check
if the curve
is within the limits shown
in the
aH
oi
ait
overall frequency response chart for metal tapes (fig. 14).
SOHZ 100Hz 200Hz
SO0Hz 1kHz 2kHz 4kHz 10kHz12.5kH2
10. Confirm that bias currents are approximately as follows
Fia.
14
when the UNIT is set at different tape mode.
g-
*Measure the voltage across the head using a EVM.
Overall frequency response i sit Metal)
+6dB
Mea
mean
+6dB
around
/7.7V (Normal position)
Standard value: around 13.3V (CrO, position)
around 18.3V (Metal position)
@
Overall gain
Condition:
Equipment:
e Record/playback mode
* EVM (Electronic Voltmeter)
® AF oscillator
* Normal tape mode
e ATT
¢ Oscilloscope
e Input level controls...
MAX
e Resistor (6009)
¢ Standard input level;
e Test tape
MIC ............... -72 +5up
(reference blank tape)
-3
...QZZCRA for Normal
LINEIN
.........
. Test equipment connection is shown in fig. 15.
. Insert the normal reference blank tape (QZZCRA).
. Place UNIT into record mode.
: ee
a 1kHz signal through ATT (—24dB) from AF oscillator, to LINE
. ae ATT until monitor level at LINE OUT becomes 0.4V.
6. Playback recorded tape, and make sure that the output level at LINE
OUT becomes 0.4V.
7. If measured value is not 0.4V, adjust it by using VR7 (L-CH) or VR8
(R-CH).
. Repeat from step (2).
AF oscillator
@
LED meter
Condition:
Equipment:
e Record mode
© EVM (Electronic Voitmeter)
¢ AF oscillator
¢ Input level controls...MAX
¢ ATT
* Oscilloscope
¢ Resistor (600Q)
. Make connections as shown in fig. 15.
2. In the recording pause mode, apply 1kHz (—24dB) to LINE
IN.
Peak level meter
3. Adjust ATT so that output level at LINE OUT is 0.4V.
Creve) Met a
afm ge g(t]
4, At this time, check that 0dB
indicator is lighted halfway
[right
Tevel i
i
[right]
(intermediate brightness between full brightness and light-
-o
30]
3 +6 dB
out: See fig. 16).
Fig. 16
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