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2) Repeat
steps
5 and
6 for
2) Repeat
steps
5 and
6 for
confirmation
(Proceed
to
confirmation
(Proceed
to
steps 7, 8 and 9 if the curve
steps 7, 8 and 9 if the curve
is now
within
the charted
is now
within
the charted
specifications as shown fig.
specifications as shown fig. 11.)
11.)
3) If the curve
still exceeds
the specifications (fig. 11),
3) If the curve still falls below the charted specifications
increase bias current further and repeat steps 5 and 6.
(fig. 11), reduce bias current further and repeat steps
5 and 6.
. Place UNIT into CrO, tape mode.
8. Change test tape to CrO, reference blank test tape (QZZCRX), and
record 1kHz, 50Hz, 100Hz, 200 Hz, 500Hz, 4kHz, 8kHz, 10kHz and
15kHz signals. Then, playback the signals and check if the curve
—F
is within the limits shown in the overall frequency response chart +27
or CrO, tapes (fig. 14).
a
9. Place UNIT into metal tape mode and change test tape to metal _,,,,
4B
reference
blank
test tape (QZZCRZ),
and
record
1kHz,
50Hz,
coy
100Hz, 200Hz, 500Hz, 4kHz, 8kHz, 10kHz, 12.5kHz and 15kHz
é
signals. Then, playback the signals and check if the curve is within "0h
the limits shown in the overall frequency response chart for metal
tapes (fig. 14).
10. Confirm that bias currents are approximately as follows when the
UNIT is set at different tape mode.
Fig. 14
e Read
voltage on VIVM
between
ground
and test point (TP
for L-CH, TP2 for R-CH) and calculate bias current by following formula:
Value read on VTVM (V)
10 (82)
Overall frequency response chart (CrO,, Metal)
Pee
"ohn 200 Hz
500Hz
kHz
2kHz
6kHz 10kHz 15kHz
Bias current (A) =
around 410uA (Normal position)
Reference value: around 530.A (CrO, position
around 800,,A (Metal position)
© Overall gain
Condition:
Equipment:
e Record/playback mode
eVTVM
e AF oscillator
¢ Normal tape mode
© ATT
* Oscilloscope
¢ Input level controls...
MAX
e Resistor (6002)
¢ Balance control...Center
¢ Test tape
e Standard input level;
(reference blank tape)
MIG wiley
eee: -69+3dB
...QZZCRA for Normal
LINEIN
.......... ~21.5+3dB
. Test equipment connection is shown in fig. 15.
Record/ playback
2. Insert the normal reference blank tape (QZZCRA).
fc
3. Place UNIT into record mode.
4. Supply a 1kHz signal through ATT (—21.5dB) from AF oscillator, to LINE IN.
5. Adjust
ATT until monitor level at LINE OUT becomes 0.40V.
7
—
6. Playback recorded tape, and make sure that the output level at LINE OUT
Lind iy 20rd mode
becomes 0.40V.
Test tape
7. If measured value is not 0.40V, adjust it by using VR9 (L-CH) or VR10 (R-CH). — recora/piayback
8. Repeat from step (2).
head
Playback mode
VIVM
Oscilloscope
Test tape
Fig. 15
@ Fluorescent meter
Condition:
Equipment:
e Record mode
e VTVM
e jnput level controls...
MAX
e ATT
e Balance control...Center
e AF oscillator
1. Test equipment connection is shown in fig. 15.
2. Supply a 1kHz signal through ATT (—24dB) to the LINE IN jack, then set the monitor switch to source position.
3. Adjust the ATT so that the output level at LINE OUT becomes 0.40V (The input level at this condition is called the standard
input level).
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