JVC SR-VS30U Service Manual page 17

Item Conditions
10 Checking Test tape : VT742
dubbing Normal tape :
calibration AC-225
11 Maximum
output
check
12 Checking
record/
playback
distortion
13 Checking
signal to
noise ratio
recording
play back
14 Checking
erasing
coefficient
Adjustment and Confirmation
1. Insert test tape VT742 into deck A and
AC-225 into deck B.
2. Dubbing the 1kHz signal of VT742 to AC-225
during high speed mode.
Playback the dubbing part of AC-225 (deck B)
and confirm that output level of 1kHz is
-28 dBs +1.5/-2 dB on both channels through
the band pass filter.
Supply 1 kHz signal to the LINE IN terminal in
the Rec. monitoring mode, and read non-clipped
signal level at the LINE IN terminal.
1. Record a 1 kHz, -20 dB signal to LINE IN
terminals.
2. Play back the recorded part. Check the output
with a distortion meter to see if the value
conforms to the standard value.
1. Record a 1 kHz, -20 dB signal. Stop the input
by disconnecting from the terminal to perform
non-signal recording.
2. Play back the recorded part. Measure the
-8dBs recording output and the non-signal
recording output for comparison using an
electronic voltmeter. Check to see if the value
conforms to the standard value.
1. Apply a 400 Hz, +20 dB signal to the LINE
terminals.
2. Perform recording with the signal enhanced
by 20 dB.
3. Erase a part of the recording.
4. Measure the output difference between the
erased part and non-erased part to compare
with an electronic voltmeter.
For the measurement using a metal tape,
connect a band pass filter between the deck and
the electronic voltmeter.
Standard value Adjust point
-28 dBs +1.5/-2 dB
LINE OUT:
more than 8 dBs
PHONES OUT:
more than -16 dBs
Normal:
Less than 2 %
CrO /Metal:
2
Less than 3 %
Normal:
More than 40 dB
CrO /Metal:
2
More than 41 dB
LINE OUT:
More than 55 dB
Tape deck
Input
(recording,
(400 Hz)
erasing)
(400 Hz)
Electronic
Band pass filter
voltmeter
(No.MB061)1-17