Philips ST-D777ES - Repair Precautions; FM Discriminator Adjustment

14
FM Discriminator ADJUSTMENT
(NULL and MONO Distortion Adjustment)
Setting:
Procedure:
1. Tune the set to 98 MHz.
2. Adjust IFT202 for 0V reading on the digital voltmeter.
................... NULL
3. Adjust IFT203 for a minimum reading on the distortion meter.
................... MONO Distortion (THD)
4. Repeat the adjustments of 2 and 3 several times.
Note : When replacing the ceramic filter, perform this alignment.
SECTION 3
ELECTRICAL ADJUSTMENTS
Precautions in Repairing
If the front end unit fails, it is difficult to repair the inner circuits, so
replace the entire front end unit.
• Standard Setting of FM Stereo RF Signal Generator.
FM SECTION 0dB = 1µV
set
FM RF SSG
1kHz
highpass
filter
distortion mete
r
FM ANTENNA (75Ω)
LINE OUT
STEREO STANDARD SIGNAL
MONAURAL
STANDARD SIGNAL
Carrier frequency : 98MHz
Modulation : Audio 1kHz
Main channel (L+R) : 33.75kHz
deviation
Sub channel (L–R) : 33.75kHz
deviation
Pilot : 7.5kHz
Deviation
Carrier frequency : 98MHz
Modulation : Audio 1kHz
75kHz deviation
set
FM RF SSG
1kHz
highpass
filter
distortion mete
r
FM ANTENNA (75Ω)
Modulation : Monaural Standard signal
Output level : 6mV (76dB) (at 75 Ω open)
LINE OUT
Digital Voltmete
r
(DC range)
TP201
NULL terminal
All the settings are performed in the Factory Preset state. (Refer to page 13.)