JVC KD-21 - Page 10

K
K
12 Recording
13 Peak level
14 Dolby N.R
circuit
No. 4150
D-21A/B/E/U
D-15A/B/C/E/J/U
signal
current
1. Set the deck in the recording mode. VR104,204
2. Input 1kHz, —10dB signal and adjust the
recording level so that LINE OUT be-
comes —5.5dBs (0.42V), and then
VU meter become OVU.
. Recording at OVU and adjust the record-
ing signal current so that output level
becomes OVU at playback.
. Repeat step (3) unti! the recording and it’s
playback level is same.
Set as same mode of No 12 (recording Peak level
signal current) and adjust semi-fixed re-
sistor VR503 so that the “0” indicator
is lighting and not lighting at ~-1~~2dB
signal down with attenuator.
. Adjust semi-fixed resistor VR504 so
that the ‘‘-5” indicate is lighting at
-5dB with attenuator.
. Adjust VR505 so that the ‘’-10” indica-
tor is lighting at -10dB with attenuator.
. Adjust VR502 so that the “+3” indica-
tor is lighting at +3dB with attenuator.
. Adjust VR501 so that the “+6” indica-
tor is lighting at +6dB with attenuator.
. Input -17dBs 1kHz signal from LINE
IN, adjust the semi-fixed resistor (VR301,
401) so that the test point W3 and W5
is 580mV (-2.5dBs)
(Do not make bias oscillator work.)
. Check the test point W1 and W9 output
to be -25dBst2dB attenuated 30dB
(-47dBs) at 1.4kHz signal and output
to be -24.3dBs +2dB attenuated 30dB
(-47dBs) at 5kHz signal.
anes 1 eo
. Adjust it when heads or
other parts are replaced.
. Set EQ and BIAS switches
according to the type of
the tape used.
. Do not adjust at chrome
tape.
. After meter gain adjust-
ment, adjust recording
signal current.
. When it adjust using 100Q
resistor across the head tips,
adjust VR104 and VR204
so that OUTPUT level be-
comes 3.8mV. (at OVU L
and R channel) at record-
ing and playback.
Set the deck in the record
mode.
Input 1kHz, 10dB, and adjust
the recording level control so
that LINE OUT level becomes
-5.5dBs
Then check the VU meter to
indicate OVU, and adjust the
peak level at it’s mode.