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@
Overall frequency
Condition:
Equipment:
response
* Record/playback mode
* VTVM
* Test tape
* Normal tape mode
* ATT
(reference blank tape)
e CrO, tape mode
* AF oscillator
... QZZCRA for Normal
* Metal tape mode
* Oscilloscope
...QZZCRX for CrO,
* Input level controls...
MAX
• Resistor (6009)
...QZZCRZ for Metal
Note:
Before
measuring
and
adjusting,
the
overall
frequency
response make sure of the playback frequency response (For
the method of measurement, please refer to the playback fre-
quency response).
Overall frequency response chart (Normal)
(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).
SO
үм
Жш
5ш
кш
Ж
We
100?
3. Supply а 1kHz signal from the AF oscillator through ATT to
LINE IN.
-
i
K
4. Adjust АТТ so that input level is -20dB below standard
Р
|
i
5
recording level (standard recording level =0 VU).
. Adjust the AF oscillator frequency to 1kHz, 50Hz, 100Hz,
200 Hz, 500Hz, 4kHz, 8kHz and 10kHz signals, and record
ув? (L-CH)
|
these signals on the test tape.
VRB (R-CH)
0
lj
. Playback the signals recorded in step 5, and check if the
=
Ó
frequency response curve is within the limits shown in the
overall frequency response chart for normal tapes (fig. 10).
(If the curve is within the charted specifications, proceed to
steps 7, 8 and 9.)
If the curve is not within the charted specifications, adjust
p
ella
Утум. pM
d
as follows;
v
б
For overal frequency
VTVM Oscilloscope response measurement
For bias voltage
measurement
Fig. 11
Adjustment (A):
Adjustment (B):
b
When the curve exceeds the
TD
When the curve falis below
overall specified frequency
:
Le
the
overall
specified
fre-
response
chart (fig. 10) as
Hi
quency response chart (fig.
shown in fig. 12.
==
®
10) as shown in fig. 13.
1) Increase bias current by
=
р
|
1) Reduce
bias current
by
turning
VR7
(L-CH) and
turning
VR7
(L-CH) and
==
VR8 (R-CH).
7
УВВ (R-CH).
а ЕЗИ
(See fig. 1 оп page 6.)
pe
QUK
Repeat steps 5 and 6 for
EE
WM
2) Repeat steps 5 and 6 for
SkHz 7kHz 8kHz
confirmation (Proceed to
6 kHz 7ана ван:
confirmation (Proceed to
Fig. 12
steps 7, 8 and 9 if the
Fig. 13
steps 7, 8 and 9 if the
curve is now within the
|
;
curve is now within the
charted
specifications
(
charted specifications as shown fig. 10.)
as shown fig. 10.)
3) If the curve still exceeds the specifications (fig.
If the curve still falls below the charted specifica-
10), increase
bias
current further
and
repeat
tions (fig. 10), reduce bias current further and
steps 5 and 6.
repeat steps 5 and 6.
7. Place UNIT into CrO, tape mode.
8. Change
test
tape
to CrO,
reference
blank
test
tape}
Overall frequency response chart (CrO,, Metal)
(QZZCRX), and record 1kHz, 50Hz, 100Hz, 200Hz, 500Hz,
4kHz, 8kHz, 10kHz and 12.5kHz 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).
. Place UNIT into metal tape mode and change test tape to
metal
reference
blank
test tape (QZZCRZ),
and
record
1kHz, 50Hz, 100 Hz, 200Hz, 500Hz, 4kHz, 8kHz, 10kHz and
12.5kHz signals.
Then, playback the signals and check if
the curve is within the limits shown in the overall frequency
response chart for metal tapes (fig. 14).
. Confirm
that bias voltage are approximately
as follows
when the UNIT is set at different tape mode.
* Measure the voltage across the head using a VTVM.
50H:
100H2
2008:
500Hz
]KHz
2кн2
ані
around
6.2V (Normal position)
Reference value: around
8.9V (CrO, position)
around 15.7V (Metal position)
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