Sony MHC-EX7 - Page 5

SECTION 2
ELECTRICAL ADJUSTMENTS
Precautions in Repairing
If
the
front
unit
fails,
it
is
difficult
to
repair
the
inner
circuits,
so
replace the entire front end unit.
The
FM
TUNED
level
must
be
adjusted
after
the
AM
TUNED
level adjustment has completed.
AM SECTION
AM Tuning Level Adjustment
Setting :
BAND switch : MW (AM)
loop antenna B
loop antenna A
AM BF signal
generator
aly
Carrer frequency : 999kKHZ
30% amplitude
modulation by 400Hz signal
Procedure :
1.
Set
loop
antenna
A
so
that
the
loop
antenna
B
input
level
becomes 55dBuz/m .
2. Tune the set to 999kHz.
3. Adjust RV1 so that the TUNED indicator goes on.
Adjustment
Location
:
MAIN
board.
(See
page
4)
FM SECTION
FM Tuning Level Adjustment
Setting :
BAND switch : FM
FM RF stereo signal
generator
FM ANTENNA terminal
75 2 coaxial
Carrer frequency : 98MHZ
modulation : 1kHz, 75kHz deviation (100%)
Output level : 250B ut (17.812V)
Procedure :
1. Tune the set to 98MHz.
2. Adjust RV2 so that the TUNED indicator goes on.
Adjustment Location : MAIN board. (See page 4)
FM POLAR Adjustment (CIS model only)
Setting :
BAND switch : FM
FM ff stereo signal
generator
FM ANTENNA terminal
7§ Q coaxial
Carrier frequency : 69MHzZ
Output level : 6008 uz (1mvV)
Procedure :
1. Connect the frequency counter to the TP1702 and adjust the
RV1702 for a frequency of 31.25kHz + 50Hz.
2. Connect the VTVM to the TP1701, receive the signal of
69MHz + 1kHz (ikHz dev.) and adjust the reading of the
VTVM to OdB.
3. Set the modulation frequency of the FM RF signal generator to
31.25kHz (10kHz dev.) and adjust the L170] and CT1701 so
that the reading of the VTVM is OdB.
4. Adjust the RV1701 so that the reading of the VTVMto 14dB.
5. Check that the separation between pins 13 and 11 of the
CN1701 is more than 18dB.
Adjustment Location : POLAR board. (See page 4)