Cassette Amplifier Section; Tuner Section - JVC UX-G1 Service Manual

4.6

Cassette amplifier section

Item Measuring condition
Head azimuth Test tape : VT703
adjustment Signal output terminal :
PHONES
(with 32 ohm load)
Tape speed Test tape : VT712
and Signal output terminal :
wow/flutter PHONES
check and (with 32 ohm load)
adjustment
PB frequency Test tape : VT738
responce Signal output terminal :
check PHONES
(with 32 ohm load)
Bias frequency Test tape : normal
check Signal output terminal :
Casssette R/P head
REC and PB Test tape : AC225
frequency Signal input : FM 22.5
responce dev, 60dBu with
adjustment emphasis
Signal output terminal :
PHONES
(with 32 ohm load)
4.7

Tuner section

Item Measuring condition
AM IF Signal input : Loop
adjustment antenna
Signal output : IC201
pin 18
AM tracking Signal input : Loop
adjustment antenna
Signal output : PHONES
(with 32 ohm load)
Tuner 114 kHz Signal input : IC101
filter the waves pin 19
adjustment Signal output : IC101
pin 18
Check and adjustment procedure
1.Plyback the test tape VT703.
2.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 of the
maximum output level.
After this adjustment, lock the head
azimuth adjusting screw with screw
sealant to cover more than a half of the
screw head.
3.When the head azimuth is maladjusted,
correct it with the head azimuth adjusting
screw.
1.Plyback the test tape VT712 by the end
of position.
2.Connect a frequency counter and check
that it reads between 2940 and 3090 Hz.
If not, adjust the frequenct with the motor
semifixed resistor.
3.Check that the wow / flutter is 0.38%
(unweighted).
Playback the test tape VT738 while confir-
ming that deviation between the 1 kHz
signal and 8 kHz signal should be
0 (+3 to -6) dB.
Set the TUNER or CD function and with
TAPE to record. Check to see if the
frequency at the measuring point (R335 or
R336) is 60 kHz +/-1 kHz if not adjust T360
until the frequency counter indicates
60 kHz +/- 1 kHz.
At TUNER, set the BAND to the FM
position, and record the reference 1 kHz
signal and 8 kHz signal altemately
repeatedly. While playing back the
recorded signal differ from that of the 1 kHz
signal by within 0 (+3 to 6) dB.
Check and adjustment procedure
1.Set the intermediate frequency sweep
generator to AM 450 kHz.
2.Adjust the T203 from maximum and
center output.
1.Set the TUNER at 522 kHz adjust T201
until the test pin of R245 voltage at
1.55 V +/- 0.1 V.
2.Set the TUNER at 1629 kHz, check the
pin of R245 voltage at 8.4 V +/- 6V.
3.Set the TUNER ang S/G at 612 kHz,
adjust T202 for maximum output.
4.Set the TUNER and S/G at 1404 kHz,
adjust T201 for maximum output.
5.Repwat the above step 3 and 4.
1.Set the unit in standby mode. Input 114
kHz signal to IC101 pin 19.
2.Adjust the T204 for output voltage
minimum.
Standard value Adjusting part
Output level : Head azimuth
within +/-2dB adjusting screw
of maximum (to be used only
output level after head re-
placement)
Phase defference
L and R channels:
minimum
2940 to 3090 Hz Tape speed :
motor semifixed
resistor
within 0.38%
check only
(unweighted)
deviation between
1 kHz and 8 kHz :
0 (+3 to -6) dB.
L203
Level difference
between REC and
PB : within 0
(+3 to 6) dB
Standard value Adjusting part
T203
T201
R245
TC201
T204
(No.MB412)1-15