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Overall frequency response chart (Normal)
COC
Ee
CO AT
I
(Recording equalizer is fixed)
1. Make connections as shown in fig. 11.
2. Place UNIT into normal tape mode and insert the normal
reference blank test tape (QZZCRA).
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3. Supply a
1KHz signal from the AF oscillator through ATT to.
4
+408
+2dB
0dB
-20B
ail
et
TT
aH
Le TT
EG
ae a
50Hz
100Hz
200Hz
500Hz
1KHz
2KHz
4KHz
1OKHz
LINE IN.
. Adjust ATT so that input level is —20dB below standard
recording level (standard recording level =O VU).
5. Adjust the AF oscillator frequency to 1kHz, 50Hz, 100Hz,
200 Hz, 500Hz, 4kHz, 8kHz and 10kHz signals, and record
these signals on the test tape.
6. Playback the signals recorded in step 5, and check if the
frequency response Curve is within the limits shown in the
~4dB
-6dB
VR7 (L-CH)
P1 (L-CH
; (
VR8 (R-CH)
LINE IN
)
TP2 avg
overall frequency response chart for normal tapes (fig. 10).
Record/
(If the curve is within the charted specifications, proceed to
ear
steps 7, 8 and 9.)
If the curve is not within the charted specifications, adjust
as follows;
(Ool L
VTVM
Oscilloscope
SNe
PRN
For overall frequency
response measurement
Fig. 11
VTVM
Oscilloscope
For bias voltage
measurement
Adjustment (A):
When the curve exceeds the
overall specified frequency
response
chart (fig. 10) as
shown in fig. 12.
Adjustment (B):
When the curve falls below
the
overall
specified
fre-
quency response chart (fig.
10) as shown in fig. 13.
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a
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L
a
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LI
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a
pa
1) Increase bias current by
[+—S
1) Reduce bias current by
turning VR7 (L-CH) and
—#
turning VR7 (L-CH) and
VR8 (R-CH).
ear
VR8 (R-CH).
(See fig. 1 on page 4.)
had
2) Repeat steps 5 and 6 for
nie 7kHz BZ
confirmation (Proceed to
steps 7, 8 and 9 if the
Curve
iS now within the
charted
__ specifications
as shown fig. 10.)
If the curve still falls below the charted specifica-
tions (fig. 10), reduce bias current further and
repeat steps 5 and 6.
2) Repeat steps 5 and 6 for
confirmation (Proceed to
steps 7, 8 and 9 if the
curve
is now
within the
charted specifications as shown fig. 10.)
3) If the curve still exceeds the specifications (fig.
3
10), increase
bias
current
further
and
repeat
steps 5 and 6.
7. Place UNIT into CrO, tape mode.
8. Change
test
tape
to CrO,
reference
blank
test
tape
(QZZCRX), and record 1kHz, 50Hz, 100Hz, 200Hz, 500Hz,
4kHz, 8kHz, 10kHz and 12.5kHz signals.
Then, playback
ATE
the signals and check if the curve is within the limits shown
1
ee
in the overall frequency response chart for CrO, tapes (fig.
Be
14).
~~
100H2z
200H2
500Hz
1KHz
2KHz
4KHz
1OKHz 12.5KHz
Fig. 14
around
5.1V (Normal position)
Reference value: around
6.6V (CrO, position)
around 11.2V (Metal position)
Condition:
Equipment:
¢ Record/playback mode
e VTVM
e AF oscillator
¢ Normal tape mode
e ATT
¢ Oscilloscope
e Input level controls...
MAX
e Resistor (6002)
¢ Standard input level;
e Test tape
MIC oo...
eee ee eee. -72* dB
(reference blank tape)
...QZZCRA for Normal
© Overall gain
. Test equipment connection is shown in fig. 15.
. Insert the normal reference blank tape (QZZCRA).
. Place UNIT into record mode.
Record/playback
head
& ODM
—
ATT
OUT jack].
>
7. If measured
value is not 0.42V, adjust it by using VR5 (L-CH) or VR6
Playback mode
VTVM
Oscilloscope
Fig. 15
e Resistor (600)
. Test equipment connection is shown fig. 16.
. Place UNIT into record mode.
. Supply 1kHz signal (-24dB) from AF oscillator, through ATT to LINE
IN.
GM
—
AF oscillator
ATT \ye"iy Record mode
VIVM
Oscilloscope
. Adjust ATT until monitor level at LINE OUT becomes 0.4V.
Fig. 16
. Check
that the level meter
LED
"0" is lit when
0.4V+1dB
output
appears at the LINE OUT.
on
level meter
—0B co |p 10/> Sip
pa'
Np'
8
ee
71
74
71
C)
Oj>
3)>
...B/C
e Balance control...Center
¢ Input level controls... MAX
Record side
¢ Check of the Dolby-B type encoder characteristics
. Make connections as shown in fig. 18.
Set the unit to the record mode. (NR select switch is OUT.)
. Apply a 1kHz signal to LINE IN.
. Adjust the ATT so that the output level at Pin 7 of IC5 (L-CH) and IC6 (R-CH) is 12.3mV.
. The output level at pin 21 should be OdB.
. Set the NR select switch to B, and make sure that the output signal level at pin 21 of IC5 (L-CH) and IC6
(R-CH) is +6+2.5dB.
. Set the NR select switch to OUT, and adjust the frequency
to 5kHz.
The output signal level at pin 21 should be OdB.
8. Set the NR select switch
to B and make
sure that the
output signal level at pin 21 of IC5 (L-CH) and IC6 (R-CH) is
+ 8dB+2.5dB.
¢ Check to Dolby-C type encoder characteristics
9. Repeat steps 1-5 above.
10. Set the NR select switch
to C and make
sure that the
output signal level at pin 21 of IC5 (L-CH) and IC6 (R-CH) is
+ 11.5dB+2.5dB.
Ooh
Wh
a
|
Record mode
+ 8.5dB+2.5dB.
BLOCI
DIN
JAC
ra
MIC JAC
RECORD/PLA
HEAD
om
LINE IN(L-
:
VRé
VR3
VR«
ERASE HEA
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