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SECTION 4
ELECTRICAL ADJUSTMENTS
Notes: Perform adjustment in the order given.
* Parts location diagram relevant to the adjustment.
Servicing Precaution
The AM RF block (FE401, FE451) section
!
L103
has been carafully adjusted at the fac-
|
CT103
08
| tory.
:
|
| When it is worn out, be sure to exchange
| Pilot Cancelt
Tracking
L102
woke,
i
Control Voltage
| it all with new sectior, because it is
: Adjustment
Adjustment
| CT102 --—-—-
Adjustment
| difficult to repair.
: eee
RV303
L301
1€202
asec ds cs as ws
\ \
1C501
|
i
aes
sf]
ers
J
tFT201
ae
ig
0
oom
|
[= mee
i
4
on
o-~
RV203
1¢c401 —
j
al |
Ra
pe
/
SS
eS
IFT204
/
fe
©-—+— Rv2ai
/
/
O-+—— avasi
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O-——- rvasz
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—} + ] |
/
| af
+
[|
1F251
co
TP201 —
RV401
a7
NULL/PLE
|1C272 |
(C251
AM Meter Level
ee
Detect Distortion | TP271
|
1C271
Adjustment
Adjustment
cT271
1FT272 -—__—___
FM SECTION
FM RF SSG
1 kHz
distortion
highpass
meter
filter
Lf
1
[So
Rete ne,
celisdl,
set
Ne tee)
FM
ANTENNA
OUTPUT
(75 Q)
» Standard signals for adjustment.
FM RF Stereo Signal
FM RF Monaural Signal
\FT/IF Distortion
Adjustment
FM Muting Level/IF
Narrow Gain Adjustment
IFT/IF Distortion
Adjustment
FM Meter Level
Stereo Operation
Adjustment
FM Muting Level/IF
Narrow Gain Adjustment
{}—-+—
Muting Width
Adjustment
Carrier frequency : 98 MHz
Modulation : Audio 1 kHz, 16.25 kHz deviation (21.7%)
Subchannel
16.25 kHz deviation (21.7%)
Pilot 19 kHz, 7.5 kHz deviation (13.3%)
Carrier frequency : 98 MHz
Modulation : Audio 1 kHz, 40 kHz deviation (53%)
= coe
Control Voitage Adjustment
Procedure:
1. Turn the set to 108 MHz.
2. Adjust L104 for 21.0 +0.2 V reading on the VTVM.
3. Tune the set to 87.5 MHz.
4. Confirm that the voltage reading on the VTVM
is
within 8.0 +1.0V.
VTVM
{dc range}
[ZI
pin (6) of 1C501
Tracking Adjustment
Setting:
IF BAND : NARROW
FM RF SSG
FM ANTENNA
(78 2)
OUTPUT
Procedure:
1. Tune the set to 108 MHz.
2. Adjust CT 101, CT102 and CT 103 for maximum read-
ing on the VTVM.
3. Tune the set to 87.5 MHz.
4. AdjustL101, L102 and L103 for maximum reading on
the VTVM.
5. Repeat the step 2 — 4 several times.
Muting Width Adjustment
Setting:
IF BAND : WIDE
MUTING switch : ON
FM RF SSG
=a
I 5
%t
o
FM ANTENNA
(75 Q)
VTVM
{dc range)
7| 1€251] 49
pins @) and (70) of 1C251
Carrier frequency:
98 MHz
Modulation:
FM RF Monaural signal
Output level:
10 mV (80 dBu)
Procedure:
1. Tune the set to 98 MHz.
2. Adjust IFT251 for OV reading on the VTVM.
~14-
NULL/PLL Detect Distortion Adjustment
Setting:
IF BAND : WIDE
MUTING
switch: ON
VTVM
{de range)
|
TP271
|
Procedure:
1. Tune the set to 98 MHz.
2. Short-circuit TP201
to the ground
(The set turns
into IF through state.)
3. Set the SSG output to 80 dBu (10 mV).
4. Adjust IFT272 for 0 V reading on the VTVM (TP271).
(Null adj.)
5. Adjust CT271 for minimum distortion reading onthe
distortion meter. (PLL Detect Distortion adj.)
6. Repeat the step 4 and 5 several times.
7. Remove the short circuit of TP201.
IFT/IF Distortion Adjustment
Setting:
IF BAND : WIDE
MUTING switch: OFF
id
!
VTVM
(de range)
pin (3) of 10203
!
Procedure:
1. Tune the set to 98 MHz.
2. Turn RV201 and RV202 to fully clockwise.
3. Set the SSG output to 40 dBu (100 nV) at monaural
modulation mode.
4. Adjust IFT201 for maximum reading on the VTVM.
(IF Distortion Pre adj. MONO)
5. Set the SSG output to 40 dBu (100 nV) at stereo
modulation mode.
6. Adjust IFT202 for maximum reading on the VTVM.
(IF Distortion Pre adj. * STEREO)
7. Adjust IFT101 for maximum reading on the VTVM
(IFT adj.)
8. Set the SSG output to 80 dBu (10 mV) at monaural
modulation mode.
9. Turn RV201 and RV202 to mechanical center posi-
tion.
10. Adjust IFT203 for the minimum distortion.
(IF Distortion adj. * MONO)
11. Set the SSG output to 80 dBu (10 mV) at stereo
modulation mode. (Lch only)
12. Adjust IFT204 for the minimum distortion.
(IF Distortion adj. * STEREO)
13. IF BAND: NARROW
14, Adjust RV204 for the minimum distortion.
(IF Narrow Distortion adj.)
Stereo Operg
Setting:
IF BAND:
MUTING
s
FM RF SS
as
(
Carrier freq
Modulatio.
Output leve
Procedure:
1. Tune the se
2. Adjust RV24
FM Muting
Setting:
IF BAND :
MUTING
g
FM RF SSG
(eb
CI
Carrier freq
Modulatio
Output lev4
Procedure:
1. Tune the s4
signal gen@
2. Turn
RV25
suddenly a
level adj.)
. IF BAND:
. Turn
RV20
suddenly a
Gain adj.)
Pw
FM Meter Le
Setting:
IF BAND :
FM RF SS
eee
Carrier freq
Modulatio
Output levé
Procedure:
1. Tune the s4
2. Adjust RV2
on the sig
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