JVC TD-W777A - Page 12

TD-W777 sacecuu |
Adjustment
Apply a1 kHz signal to the LINE
IN terminals, record a 1 kHz sig-
nal at —20dBs input for both (L
and R) channels ona normal tape.
Play back the recorded part, and
adjust the recording level con-
trols so that LINE OUT terminal
level becomes —8 dBs.
Then adjust VR103 and 203 so
that LINE OUT terminal level
becomes —8 dBs.
Adjusting
point
For Normal
tape:
L : VR103
R : VR203
Standard
value
Normal:
—8+3dBs
CrO,:
—8+3dBs
Metal:
—8+3dBs
Remarks
Perform the adjustment using a
normal tape. Level difference be-
tween recording and playback for
SA/CrO, and metal tapes should
be less than 2 dB, and that be-
tween left and right channels
should also be less than 1 dB.
*6 | Recording | 1)
gain
2)
*7 | Checking 1)
record/
playback 2)
distortion
8 | Checking 1
signal to
noise ratio in
recording/
playback 2
~—
—
Record a 1kHz, —20dBs signal
to LINE IN terminals.
Play back the recorded part.
Check the output with a distor-
tion meter to see if the value con-
forms to the standard value.
Record a 1 kHz, -20dBs signal.
Stop the input by disconnecting
from the terminal to perform
non-signal recording.
Play back the recorded part. Mea-
sure the —8dBs recording output
and the non-signal recording out-
put for comparison using an elec-
tronic voltmeter. Check to see if
the value conforms to the stand-
ard value.
9 | Checking 1)
erasing
coefficient | 2)
3)
4)
Apply a 1 kHz, -20dBs signal to
the LINE IN terminals.
Perform recording with the signal
enhanced by 20 dB.
Erase a part of the recording.
Measure the output difference
between the erased part and non-
erased part to compare with an
electronic voltmeter.
Normal tape:
Less than 2%
CrO, tape:
Less than 3%
Metal tape:
Less than 2%
(THD)
Normal, CrO, &
Metal tapes:
More than 42 dB
Be sure to perform this checking
following bias current and record-
ing level checking.
Apply an input level to LINE IN
terminals with the recording level
controls set to maximum so that
the peak level indicator reads
O dB.
More than 65dB
For the measurement using a
metal tape, connect a band pass
filter between the deck and the
electronic voltmeter.
ie sing
(recording,
(1 kHz) erasing)
(4 kHz)
|
:
Electronic
Band pass filter
12 (No. 4292)