Electrical Adjustment Procedure - JVC TD-W717TN Service Manual

TD
-
W 717 TNC
/ J
TD
-
W 718 BKA
/ B / E
/
EN /G/ U
/ UT
Electrical Adjustment Procedure
Item
Check and Adjustment
Input signal
( Frequency , level )
Output raise
value , deviation value
1 Cheking
DOLBY
circuit
(
Rec
.
mode )
( BIAS
-
CUT )
Signal input : LINE IN
Cal
.
level
:
400 Hz
,
-
8 dBs
Output terminal TP :
NR IC 831
@
&
( §
)
1
kHz
,
cal
.
- 40 dB + 5.7 dB
±
2 dB
DOLBY B
( Rec )
5 kHz
,
Cal
.
-
20 dB
+
3.5 dB
±
1.5 dB
0.5
1 kHz
,
Cal
.
0 dB
±
i
.
odB
pin .
+
16.2
dB
±
2
dB
1
kHz
,
Cal
.
-
40
DOLBY C
( Rec )
5 kHz
,
Cal
.
-
20 +
2.9 dB
±
2.5 dB
1
kHz ,
Cal
.
OdB
±
1
dB
Item Conditions Adjustment and Confirmation
Standard Adjusting
* 2 Play back
level check
Play back VTT 727
.
Check that the level at LINE
OUT is
-
4.5 dBs
±
1 dB
.
Difference between Lch and Rch must be less
than 1 dB at
LINE OUT
.
LINE OUT
-
4.5 dBs
±
1 dB
Phone Out
-
14.5 dBs
±
2 dB
Test tape
VTT 727
:
400 Hz
}
Deck
@
L : VR
116
R : VR 216
Deck
@
L : VR
111
R : VR 211
* 3 Playback
frequency
response
adjustment
Test tape
TMT
735
:
1 kHz / 12.5 kH
2
VTT
739
: 1 kHz
/ 63
Hz
Play back TMT 735 test tape
,
and adjust VR 116
,
VR 216 ( deck
[ ¥ ]
) and VR 111 , VR 211
( deck
[
A
]
)
so that deviation of 12.5 kHz to that of 1 kHz is
0
±
0.5 dB ( deck A ) and 0
±
0.5 dB
( deck B )
.
Then , play back VTT 739 test
tape to confirm
that deviation of 63 Hz
to 1
kHz is +
2
±
3 dB
.
with 12.5 kHz
as reference ,
0
+
0.5 dB
( deck
[
A
]
) and
0
±
0.5 dB
( deck
[
B
]
)
at
1 kHz
63
Hz ( check ) :
+
2
±
3 dB
Deck
\
B
\
L 8451
Deck
|
Al
L 8401
Tape
: Metal
Mode
:
REC
Frequency
counter
Input impedance
:
more than 1 MQ
.
( See pagel 8 )
Deck
[
B
]
TP : CN
846 pin 1
Deck
0
TP : CN 841 pin 1
*
4 Bias
frequency
adjustment
Connect frequency counter to the CN 846 ( deck
[
B
]
) and CN 841 ( deck
[
A
]
) and adjust L 8451
( deck
{
B
\
)
and L 8401 ( deck
[
A
]
) so that the
counter
reads 95 kHz
.
95
kHz
±
0.5
kHz
Deck
[
A
]
L : L 1401
R
:
L 2401
DeckH
L : L 1451
R
:
L 2451
DC
.
Voltmeter
Deck
|
A
]
TP : CN
841
Deck
H
TP : CN 846
* 5 Slave
oscillation
( HX PRO )
adjustment
This step must be performed after the bias
frequency
adjustment
.
Load
a
metal
tape
and
set
the deck
to
the
recording mode
.
1
.
Adjust for deck
[
A
]
Adjust L 1401 and L
2401 to minimize respec
-
tive voltages of CN 841 (
PIN
3
-
4 ) at Lch and
( PIN 3
-
5 ) at
Rch
.
2
.
Adjust for
deck
[
B
]
Adjust L 1451 and L 2451 to minimize respec
-
tive voltages of CN 846 ( PIN 3
-
4 )
at
Lch and
( PIN 3
-
5 ) at
Rch .
Minimum
20 (
No
.
4358
)