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ADJUSTMENT – 1 <TUNER>
7
1
7
A
MAIN C.B
L771
L772
1
IC770
TP3
(CLK)
TP6
(DC)
TP9
TP8
(RCH)
(LCH)
3
4
6
7
9
10
< TUNER SECTION >
1. Clock Frequency Check
Settings : • Test point :
TP3(CLK)
Method :
Set to AM 1602kHz and check that the test
point is 2052kHz ± 0.045kHz
2. AM VT Check
Settings : • Test point :
TP4(VT)
Method :
Set to AM 1710kHz and check that the test
point is less than 8.5V.
Then set to AM 530kHz and check that the
test point is more than 0.6V.
3. AM Tracking Adjustment
Settings : • Test point :
TP8(Lch), TP9(Rch)
• Adjustment location : L981(1/3)
Method :
Set to AM 999kHz and adjust L981(1/3) so
that the test point becomes maximum.
4
7
8
TP7
(STOP)
TP5
L981
3
(DC)
TP4(VT)
2
FFE801
5
4. AM IF Adjustment
Settings : • Test point :
TP8(Lch), TP9(Rch)
L772 ........................... 450kHz
5. FM VT Check
Settings : • Test point :
TP4(VT)
Method :
Set to FM 87.5MHz and check that the test
point is more than 0.5V.
Then set to FM 108.0MHz and check that the
test point is less than 8.5V.
6. FM Tracking Check
Settings : • Test point :
TP8(Lch), TP9(Rch)
Method :
Set to FM 98.0MHz and check that the test
point is less than 9dB.
53
7. DC Balance / Mono Distortion Adjustment
Settings : • Test point :
TP5, TP6
(DC balance)
TP8, TP9
(Distortion)
• Adjustment location : L771
• Input level :
54dB
Method :
Set to FM 98.0 MHz and adjust L771 so that
the voltage between TP5 and TP6 becomes
0V ± 0.04V.
Next, check that the distortion is less than
1.3%.
8. Auto Stop Level Check
<AM>
Settings : • Test point :
TP7(STOP)
• Input level :
50dB
Method :
Set to AM 999kHz and check that the auto
stop is at input level of 50dB +10 /–15dB.
<FM>
Settings : • Test point :
TP7(STOP)
• Input level :
25dB
Method :
Set to FM 98.0MHz and check that the auto
stop is at input level of 25dB ± 10dB.
9. Output Level Check
<AM>
Settings : • Test point :
TP8(Lch), TP9(Rch)
• Input level :
74dB
Method :
Set to AM 999kHz and check that the test
point is 30mV ± 3dB.
<FM>
Settings : • Test point :
TP8(Lch), TP9(Rch)
• Input level :
54dB
Method :
Set to FM 98.0MHz and check that the test
point is 120mV ± 3dB.
10. FM Separation Check
Settings : • Test point :
TP8(Lch), TP9(Rch)
• Input level :
54dB
Method :
Set to FM 98.0MHz and check that the test
point is more than 25dB.
PRACTICAL SERVICE FIGURE
<TUNER SECTION>
<FM SECTION>
IHF Sensitivity :
Less than 10dB
(THD 3%)
[at 87.5MHz]
Less than 9dB
[at 98.0 / 108.0MHz]
S/N 50dB Quieting sensitivity :
Less than 36dB
[at 87.5 / 98.0 / 108.0MHz]
Signal to noise ratio :
More than 68dB (MONO)
(Input 54dB)
More than 66dB (STEREO)
[at 98.0MHz]
Distortion :
Less than 1.2% (MONO)
(Input 54dB)
Less than 2.0% (STEREO)
[at 98.0MHz]
Auto stop level :
25dB ± 10dB
[at 98.0MHz]
Stereo separation :
More than 30dB
[at 98.0MHz]
Intermediate frequency : 10.7MHz
<AM SECTION>
Sensitivity :
Less than 62dB
[at 603kHz]
Less than 58dB
[at 999 / 1404kHz]
Signal to noise ratio :
More than 36dB
(Input 74dB)
[at 999kHz]
Distortion :
Less than 1.5%
[at 999kHz]
Auto stop level :
50dB + 10/– 15dB
[at 999kHz]
Intermediate frequency : 450kHz
54
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