Hitachi D-RV7 Servicehandbuch Seite 7

3. Playback Gain Adjustment and Level Meter Check
(1) Playback gain adjustment
Adjustment Adjustment
Input
value point
Dolby
490 mv dB RTI L, R
reference tape
Adjustment procedure
Connect the electronic voltmeter to the LINE OUT
nals, playback the Dolby reference tape and adjust so that
the reading of the electronic voltmeter is set to the adjust-
ment value.
(2) Level meter check
I) Connect the audio oscillator to the LINE IN termi-
nals via an attenuator to set the deck to the
mode.
2) Input a 400 Hz signal and adjust the LINE
terminal output voltage to 490 mV —0.5 dB using
the attenuator.
3) At this time, adjust RT4L, R so that the O dB point
of the meter turns from OFF to ON.
5. Bias Current Adjustment and REC/PLAY Output Level Adjustment
Set RT3L, R to the center positions and record at the recording
check the playback level.
Recording
Order Tape
Frequency
Level
Normal tape 1.2k/12k
1 O dB —23 dB
2 Normal tape 400 —3 dB
3 Normal tape 1.2k/12k O dB —23 dB
*Chrome tape
4 12k/12k O dB —23 dB
1.2k(12k O dB
5 —23
METAL tape
Adjustment procedure
(1) Bias current adjustment
1) Connect an audio oscillator to the LINE IN termi-
nals via an attenuator, set the deck to the record
mode, and adjust the output of the audio oscillator
so that the reading Of the meter is O dB. Then, ad-
just the attenuator to set it to O dB —23 dB (Fre-
quency: 1.2 kHz).
2) Record in this state and then set the frequency
the audio oscillator to 12 kHz. and then perform
cording.
3) Play back the recorded section,read the output
4. Dolby NR operation check
• Dolby B type
(I) Record using metal tape (ME C46) at 5 kHz, —40
dB with respect to the Dolby
record with ' 'Dolby OFF" and ."Dolby
(2) Play back with ' 'Dolby OFF"
output difference between
"Dolby B" is approx. 10 dB.
e Dolby C type
(1) Record using metal tape (ME C46) at I kHz, —40
termi-
dB with respect to the Dolby
record with "Dolby OFF" and ' ' Dolby
(2) Play back with "Dolby OFF"
output difference between
"Dolby C" is approx. 16 dB.
record
OUT
levels shown in the table below to adjust for each tape and
level Playback level
Adjustment Adjustment
Level
point location
RT3L, R
ATT within +1 dB
within ±0.5 dB RT2L, R
ATT
ATT Check
within +1 .O dB
ATT within dB Check
dB ATT within ±3 dB Check
check that the output difference
frequencies is within ± I dB.
4) When the output difference is out Of ± I dB range,
adjust RT3L, R properly and repeat recording/play-
ing back in the same way so that the output
ence is within ± I dB.
of Perform check only With CHROME,
re- When the output difference is out of the specifica-
tion (±3 dB), perform adjustment
and
tape again.
D-RV7
D-RV7
REC/PLAY output level adjustment
(2)
1) Connect an audio oscillator to the LINE IN termi-
nals, input a 400 Hz signal, set the unit to the re-
level. Continuously
cord mode and adjust the output
B".
lator so that the reading of the meter is —3 dB be-
and check that the
fore recording.
"Dolby OFF" and
Cassette Chassis Checking and Adjustment
6.
Item
level. Continuously
inspection
No.
C".
Pressure roller Compression
and check that the
"Dolby OFF" and
Fast forward,
rewind
2 Torque
Pl
Feeding
3 Back tension
Take-up
Feeding side
Braking
4
torque
Take-up
Adjustment
procedu re
(1)
(2)
Back
(1)
on feeding
(1)
(1)
Check that exposed
from the supply circuit
ment repaired to the customer.
between the 2
• Checking method
Power switch is set to ON.
Next, measure the resistance
both poles of attachment
differ-
and the exposed parts (Parts such as Knob, Cover,
METAL tapes.
etc. where the customer
check that the resistance
using NORMAL
more.
2) Playback the recorded section to check that the out-
put is within
3) When the output
of the audio oscil- range, adjust
ing/playing
difference
Item
Value
strength 330 ±40g To be measured with tension
70g•cm—
To measured with torque
back
side 2.5&4 .Og•cm
TO be measured using torque
(Fig. 12)
2 .Og•cm
side
50g •cm or more To be measured using tension
side
Drive force
Pressure
compression
Pressure roller {right)
compression strength
o
Fig. II
Brake
Back tension
tension
on take-up side
side
Braking torque
on feeding side
Fig. 12
parts are acceptably insulated
before returning the instru-
value between the
cup (Power supply plug)
is easy to touch.) and
value is 500 kohms or
O dB ±0.5 dB.
difference is out of the ±0.5 dB
RT2L, R properly and repeat record-
back ih the same way so that the output
is within ±0.5 dB.
Remarks
gauge. (Fig. I I)
measuring cassette.
measuring cassette in playback mode.
gauge in stop state. (Fig. 13)
roller (left)
strength
plate
Braking torque
on take-up side
Fig. 13
INSTRUNENT
( Exposed part)
Insulation tester (DC 500V)