JVC KD-A66 Service Manual

KD-A66A/B/C/E/J/U
Operation
The operation is described in accordance with Fig. 3 (opera-
tional timing chart).
1.
No. 4193
Press the START button.
At this time, the READY LED in the display section
flickers, indicating that the computer is in operation.
The tape is rapidly fed at 1.6 sec to avoid the use of
the leader tape section.
The recorder enters the recording mode.
In this mode, a blank recording (no-signal recording) is
performed for 2.8 sec to stabilize the mechanical and
electrical systems. Subsequently, two marker signals
and eight pairs of 1 and 7 kHz test signals are recorded.
At this time, the bias current is varied 8 steps every 60
msec by +10% to -30% more than the preset value.
(The bias current, equalization level and tape sensitivi-
ty values are preset, each determined by using a stand-
ard tape.) (Fig. 4)
Preset value
Bias
current
8
step
bias
current
variations
ome
Markers
ms 1kHz 7 kHz 1 kHz
AN NK
Ae
Pe Z
Tone &
ABBHHEE
Anew e eG
ZEZeZceZes J
Markers
ze
—— 1kHz 7 kHz
1121314415 |6|7
60 msec
NY
ON
NNN
REC
Set point
Fig. 4
The tape is rewound to return to the position at the
1.6 sec lapse point from the beginning of the previous
blank recording.
Data on the tape is reproduced, and the reproduction
levels of the 1 and 7 kHz test signals are compared in
order to properly determine their coinciding step.
The microcomputer detects these coincident steps.
At this time, the recorder initiates recording and per-
forms a blank recording for 2.8 sec. Subsequently, the
recorder records the markers, and enters the 12.5 kHz
signal recording state after recording the 1 kHz refer-
ence level, and increasingly varies the equalization level
of the right channel by 8 steps very 60 msec.
Further, after recording the 1 kHz reference signal of
the left channel, the recorder increasingly varies the
equalization level. Next, to adjust the tape sensitivity,
the recorder increasingly varies the 1 kHz recording
level by 8 steps every 60 msec. The difference between
the smallest and largest levels is +4 dB. (Fig. 5)
As shown in Fig. 2, the tape is rewound to the position
at the 1.5 sec lapse from the beginning of recording;
see item 6.
Right equalizer Left equalizer Tape sensitivity
Markers
tight equalizer Left equalizer
Markers
aire! Set point
The recorder enters the reproduction mode, and the
microcomputer first compares the reproduction levels
of the 1 kHz reference signal and the 12.5 kHz signal
of the right channel.
In recording, since the 12.5 kHz signal is increasingly
varied by the right equalizer, its reproduction level will
coincide with that of the 1 kHz reference signal. Sub-
sequent to storing this coincident point, the same
operation is also performed on the left channel.
Next, the tape sensitivity is adjusted. Prior to this, the
recorder stores the reproduction level of the 1 kHz
reference signal of the right channel during recording
(item 6), and during reproducing, seeks its coincident
point with the 8-step level varied tape sensitivity adjust-
ing signal.
Is the
SERVICE switch at thé
OFF position?
Setting of preset vaiues and
auto set values
's the
START switch at the
ON position?
Setting of frequency response
sensitivity
in this
ror the first?
Rewinding the tape to
its starting position
Setting of auto set values |
Fig. 6

JVC KD-A66 Specifications

General

Brand	JVC
Model	KD-A66
Category	Cassette Player
Language	English