DHC-EX77MD, DHC-MD77, MHC-EX66, ST-EX77, ST-EX770 - Sony Audio Service Manual (repair manual). Page 8

Read Sony DHC-EX77MD / DHC-MD77 / MHC-EX66 / ST-EX77 / ST-EX770 Service Manual online

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)
SECTION 3
ELECTRICAL  ADJUSTMENTS
AM RF
signal generator
30 % amplitude modulation by 
400 Hz signal
Carrier frequency : 999 kHz (at 9 k step)
              1,000 kHz (at 10 k step)
Output level         : 25 dB
µ
loop antenna
set
loop antenna
supplied accessories
60 cm
AM antenna terminal
field strength dB(
µ
V/m)=
RF SSG output level dB (
µ
V/m)–26 dB

Procedure:
1. Set loop antenna A so that the loop antenna B input level be-
comes 55 dB
µ
/m.
2. Tune the set to 999 kHz or 1,000 kHz.
3. Adjust RV1 so that the TUNED indicator goes on.

Adjustment Location : MAIN board.
 FM  SECTION
FM Tuning Level Adjustment
Setting :
BAND switch : FM
Adjustment Location :
[MAIN BOARD] – Component Side –
CN101
TM1
RV2
FM Tuning Level Adjustment
RV1
AM Tuning Level Adjustment
FE2
IC1
CN102

Procedure:
1. Tune the set to 98 MHz.
3. Adjust RV2 so that the TUNED indicator goes on.

Adjustment Location : MAIN board.
– 8 –
FM RF Stereo signal
generator
Carrier frequency : 98 MHz
Moduration           : AUDIO 1kHz,75 kHz 
                               deviation (100%)
Output level          : 26 dB
µ
 (17.8 
µ
V)
set
FM antenna terminal
(75 
Ω
 coaxial) 

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