JVC RC-BX30, Service Manual

Page: 15 / 24

RC-BX30
1-15
Cassette amplifier section
Item Measuring condition Check and adjustment procedure Standard value Adjusting part
Play back the test tape VT702 (8kHz).
Adjust the head azimuth adjusting screw so that the
phase difference between the R and L channels is
minimized at an output level that is within (+2dB-2dB)
of the maximum output level in the FWD and REV
operations. After this adjustment, lock the head
azimuth adjusting screw with screw sealant to cover
more than a half of the screw head.
When the head azimuth is maladjusted, correct it with
the head azimuth adjusting screw in the FWD and
REV operations alternately.
Play back the test tape VT712 (3kHz) by the end
portion.
Connect a frequency counter and check that it reads
between 2940 and 3090Hz. If not, adjust the
frequency with the motor semifixed resistor.
Check that the wow/flutter is within 0.38%
(unweighted).
Play back the test tape VT702 while con-firming that
deviation between the 1kHz signal and 8kHz signal
should be 0(+3dB~-6)dB.
Set the FUNCTION switch to TAPE and the record
and play tape mechanism, check to see if the
frequency at the measuring point is (80kHz+2kHz
-2kHz) if not adjust L201 until the frequency counter
indicates (80kHz+2kHz-2kHz).
Set the FUNCTION switch to the radio position, set
the BAND switch to the FM position, and record the
reference 1kHz signal and 8kHz signal alternately
repeatedly. While playing back the recorded signal
differ from that of the 1kHz signal by within 0 (+3~
-6)dB.
Test tape:
VT702 (8kHz)
Signal output terminal:
PHONES
(with 32 ohm load)
Test tape:
VT712 (3kHz)
Signal output terminal:
PHONES
(with 32 ohm load)
Test tape: VT702
Signal output terminal:
PHONES
(with 32 ohm load)
Tape: Normal
Signal output terminal:
Cassette REC./PLAY
HEAD
Test tape: AC225
Signal input:
FM22.5 DEV 60dBu
with emphasis
Signal output terminal:
PHONES
(with 32 ohm load)
Head azimuth
adjustment
Tape speed and
wow/flutter check
and adjustment
PB frequency
response check
Bias frequency
check
REC and PB
frequency
response
adjustment
1.
2.
3.
1.
2.
3.
Output level:
Within (+2dB-2dB) of
maximum output
level
Phase difference R
and L channels:
Minimum
2940 to 3090Hz
Within 0.38%
(unweighted)
Deviation between
1kHz and 8kHz:
0(+3dB~-6)dB
Level difference
between REC and
PB: Within
0 (+3~-6)dB
Head azimuth
adjusting screw
(To be used only
after head
replacement)
See Fig.1 on
page 1-16.
Tape speed:
Motor semifixed
resistor
See Fig.2 on
page 1-16.
Check only
L201
See Fig.4 on
page 1-16.
Tuner section
Item Measuring condition Check and adjustment procedure Standard value Adjusting part
Set the intermediate frequency sweep generator to
MW/SW 455kHz.
Adjust the T102 for maximum and center output.
Set the intermediate frequency sweep generator to
FM (10.7MHz).
Adjust the T101, T103 for maximum and center
output.
Set the dial at low end, set the S/G at (5.75MHz
+0.4MHz-0.4MHz). Adjust the L104, check to see the
output is maximum.
Set the dial at high end, set the S/G at (17.8MHz
+0.5MHz-0.5MHz). Adjust the VC101, check to see
the output is maximum.
Set the dial while receiving a 7MHz signal from S/G at
maximum. Adjust the L101, check to see the output is
maximum.
Signal input:
Loop ANTENNA
Signal output:
IC101 pin19
Signal input:
FMANT, FMGND
Signal output:
IC101 pin19
Signal input:
Dummy antenna
ANT
GND
Signal output:
PHONES
(with 32 ohm load) MW/SW
IF adjustment
FM IF adjustment
SW tracking
adjustment
1.
2.
1.
2.
1.
2.
3.
T102
See Fig.3 on
page 1-16.
T101, T103
See Fig.3 on
page 1-16.
L104
VC101
L101
See Fig.3 on
page 1-16.