JVC KD-2A User Manual

Procedure
2. Bias current
3. REC/PB level
. Check of
REC/PB
distortion
. Check of
REC/PB signal
to noise ratio.
. Check of
erasure ratio
Input 1kHz and 10kHz (OVU—20dB)] Rec amp
signals from LINE IN to record in
reference tape.
When playback it’s tape, adjust R
R514, 614 (normal) and R513, 613
(chrome) so that OUT PUT levels
become equal values.
R/P HEAD
[Easy method]
. Set the deck to record mode.
. Connect a 1002 resistor to the
ground side (at record mode) of
the head wire.
. Measure it’s voltage.
. Input 1kHz (-10dBs) signal from
LINE IN, adjust the REC master
volume so that LINE OUT level
become —8dBs.
. Make recording in such a way
that the level meters indicate
zero VU at normal mode or
chrome mode (as same Left
channel or right channel)
. Playback it and adjust the semi-
fixed resistors for REC level so
that the level meters indicate
zero VU.
. Input 1kHz (-10dBs) signal
from LINE IN, and make re-
cording in such a way that the
level meters indicate zero VU.
. Playback and check it that the
distortion become rating less.
. Input 1kHz OVU signal from
MIC IN, make recording that
the level meters indicate zero
VU, and then make recording at
no signal mode.
. Playback it’s tape and measure
the signal to noise ratio by
V.T.V.M.
. Input and make recording as
same 5.
. Continue recording to up 20dB
the signal level.
. Rewind it’s tape and erase the
part of it.
. Measure output level to the re-
cording part ratio the erasing
part.
circuit board
Normal
R514, 614
(BIAS)
Chrome
(BIAS)
Normal
33mV
Chrome
53mV
Main amp
circuit board
Normal
[R149, 249
REC LEVEL]
Chrome
[R150, 250
REC LEVEL]
Normal
3% less
Chrome
4% less
Normal
| KD-2A/B/C/E/J/U
Remarks
. Standard method for bias
adjustment of cassette deck
are adjusted the frequency
response at REC/PB. Be-
cause the cassette tape is
great affection to bias cur-
rent of frequency responce
than open-reel tape. When
you measure the bias curr
rent, can you doing the
easy way as below.
. If not correct the bias cur-
rent, frequency responses are
shown as the next figure.
too fow
most
switable
too high
KHz 1OKH 2
. If the meter pointer moving
at PB mode when your finger
touch a head wire, it’s wire
is ground side at Rec mode
(Because the head wire of 2
head deck become opposite
polarity at playback and at
cords)
4. Must use the shield wire.
cw Response(dB)
The difference in level of
each channel is less than 1dB.
Make this adjustment after
making sure bias current, and
REC level.
REC volume at maximum.
42dB or more
more
Chrome
42dB or
more
When measure the erasing ratio,
connect the B.P.F (Band pass
filter) to the deck from the
V.T.V.M. (mitivolts)
No. 4151

JVC KD-2A Specifications

General

Brand	JVC
Model	KD-2A
Category	Cassette Player
Language	English