Technics RS-D400 Serviceanleitung Seite 11
Inhaltsverzeichnis
(Recording equalizer is fixed)
Make connections
as shown in fig. 11.
1.
Place UNIT into normal tape mode and insert the normal
2.
reference
blank test tape (QZZCRA).
3. Supply a 1kHz signal from the AF oscillator through ATTto
LINE
IN.
4. Adjust ATT so that input level is —20dB below standard
recording level (standard recording level
VIJ).
5. Adjust the AF oscillator
frequency to 1kHz, 50Hz, IOOHz,
200 Hz, 500 Hz, 4kHz, 8kHz and 10kHz signals, and record
these signals
on the test tape.
Playback the signals recorded in step 5, and check if the
6.
frequency
response
curve is within the limits shown in the
overall frequency
response
chart for normal tapes (fig. 10).
(If the curve is within the charted specifications,
proceed to
steps 7, 8 and 9.)
If the curve is not within
the charted
specifications,
as follows;
Adjustment
(A):
When
the curve
exceeds
the
overall
specified
frequency
response
chart
(fig. 10) as
shown in fig. 12.
1) Increase
bias current
by
—3dB
turning
VR7 (L-CH) and
VR8 (R-CH).
IkHz 2kHz 3kHz
12SkHZ
(See fig. 1 on page 4.)
'kHz
9 kHz
2) Repeat steps 5 and 6 for
6kHz
8kHz
confirmation
(Proceed to
Fig. 12
steps
7, 8 and 9 if the
curve
is
now
within
the
charted
specifications
as shown fig. 10.)
3) If the curve still exceeds
the specifications
(fig.
10), increase
bias
current
further
and
repeat
steps 5 and 6.
7. Place UNIT into Croa tape mode.
8. Change
test
tape
to Cr02
reference
blank
test
(QZZCRX), and record
1kHz, 50Hz, IOOHz, 200Hz, 500Hz,
4kHz, 8kHz, 10kHz and 12.5kHz signals.
Then, playback
the signals
and check if the curve is within the limits shown
in the overall frequency
response chart for Cr02 tapes (fig.
14).
9. Place UNIT into metal tape mode and change test tape to
metal
reference
blank
test
tape
(QZZCRZ),
and record
1 kHz, 50Hz,
IOOHz, 200Hz,
500Hz,
4kHz,
8kHz,
10kHz
12.5kHz signals.
Then, playback
the signals
and check if
the curve is within
the limits shown in the overall frequency
response
chart for metal tapes (fig. 14).
10. Confirm
that bias voltage
are approximately
as follows
when the UNIT is set at different
tape mode.
•Measure
the voltage across the head using a EVM.
around
5.1 V (Normal
position)
Reference value: around
6.6V (Croz position)
around 11.2V (Metal position)
@ Overall gain
Condition.
• Record/playback
mode
• Normal tape mode
• Input
level controls...MAX
• Standard
input level;
. .-72+5dB
MIC
LINEIN............-24±4dB
Overall frequency
response chart (Normal)
•m
IDA":
Fig. 10
VR7 (LCH)
600 n
VR8
ooo
00
TP2 (R.CH)
UNE IN
Record/
ATT
AFOsc.nator
playback„
OSCPtayüCk L' E OUT
adjust
'record
mode
EVM Osctooscope
For overall frequency
EVM Osc.noscope
response
measurement
For bias voltage
Fig. 11
rrEasurernent
Adjustment
(B):
When
the
curve
falls
below
the
overall
specified
fre-
quency response
chart (fig.
10) as shown in fig. 13.
1)
Reduce
bias current
by
turning
VR7 (L-CH) and
VR8 (RCH).
4 kHz
2)
Repeat
steps
5 and 6 for
confirmation
(Proceed to
6kHz
8kHZ
steps
7, 8 and 9 if the
Fig. 13
curve
is
now
within
the
charted
specifications
as shown fig. 10.)
3)
If the curve still
falls below
the charted
specifica-
tions
(fig. 10), reduce
bias current
further
and
repeat steps 5 and 6.
tape
Overall frequency
response chart (Cr02, Metal)
and
Fig. 14
Equipment:
• EVM (Electronic
Voltmeter)
• AF oscillator
• Oscilloscope
• ATT
• Resistor
(600Q)
• Test tape
(reference
blank tape)
QZZCRA
for
Normal
Test equipment
connection
is shown in fig. 15.
1.
2.
Insert the normal reference
blank tape (QZZCRA).
3.
Place
UNIT
into
record
mode.
Supply a 1 kHz signal through
4.
IN.
Adjust ATT until monitor level at test points [TP3 (L-CH), TP4 (R-CH))
5.
becomes
0.42V [0.4V±1dB
at test LINE OUT jack].
6.
Playback
recorded
tape, and make sure that the output
points [TP3 (L-CH), TP4 (R-CH)I becomes 0.42V [0.4
OUT jack].
If measured
value is not 0.42V, adjust
7.
(RCH).
8.
Repeat from step (2).
Level
meter
Condition:
• Record
• Input level controls...MAX
1.
Test equipment
connection
is shown fig. 16.
2.
Place
UNIT
into
record
mode.
3.
Supply 1kHz signal (—24dB) from AF oscillator,
dB
IN.
Adjust ATT until monitor
level at LINE OUT becomes
4.
5.
Check
that the level meter
appears at the LINE OUT.
O
Dolby NR circuit
Condition:
• Record
• Dolby NR switch...lN/OUT
• Dolby NR select switch
• Input level controls...MAX
Record
side
• Check of the Dolby-B type encoder characteristics
1.
Make connections
as shown in fig. 18.
2.
Set the unit to the record mode. (NR select switch is OUT.)
3.
Apply a 1kHz signal to LINE IN.
Adjust the ATT so that the output
4.
5.
The output
level at pin 21 should be OdB.
6.
Set the NR select switch
to B, and make sure that the output
(R-CH) is +6±2.5dB.
7.
Set the NR select switch to OUT, and adjust the frequency
to 5kHz.
The output
signal level at pin 21 should be OdB.
8.
Set
the
NR
select
switch
output signal level at pin 21 of IC5 (L•CH) and IC6 (R-CH) is
+ 8dB±2.5dB.
• Check to Dolby-C type encoder characteristics
9.
Repeat steps 1-5 above.
10.
Set
the
NR
select
switch
output
signal level at pin 21 of IC5 (L-CH) and IC6 (R-CH) is
+ 11.5dB±2.5dB.
11.
Set the NR select switch
to OUT and adjust the frequency
to 5kHz.
The output
signal at pin 21 should be OdB.
12.
Set
the
NR
select
switch
output signal level at pin 21 of IC5 (L-CH) and IC6 (R-CH) is
+ 8.5dB±2.5dB.
O
ATT (—24dB) from AF oscillator,
to LINE
AF OSCIilator
level at test
Record/ playoack
dB at test LINE
it by using VR5 (L-CH) or VR6
Test lape
Equipment:
• EVM (Electronic
mode
• Resistor
(600Q)
+6
through
ATT to LINE
+3
0.4V.
LED "0"
is lit when 0.4V±1dB
output
-6
LINE our
-10
6009
oo
ONEIN Recorc mode
EVM
Osouoscoøe
Fig. 16
Equipment:
mode
• EVM (Electronic
Voltmeter)
• ATT
Resistor
(600Q)
. BIC
• Balance
control...Center
level at Pin 7 of IC5 (L-CH) and IC6 (R-CH) is 12.3mV.
signal
level at pin 21 of IC5 (L-CH) and IC6
to
B and
make
sure
that
the
Record
LINE IN
to
C and
make
sure
that
the
ATT
AF oscillator
to
C and
make
sure
that
the
Fig. 18
BLOCK
Record/91ayback
6009
head
o
ATT
Record moce
LIN
IN
rest tape
EVM
Osc'lloscope
Fig. 15
Voltmeter)
• AF oscillator
RECORI
• Oscilloscope
H EAD
+6
+3
LINE
—6
-10
left
right
Fig. 17
• AF oscillator
VR3
• Oscilloscope
ERASI
mode
NOTES:
lcs
Oscilloscope
EVM
IC6
Inhaltsverzeichnis
