Fm Polar Adjustment (Rx90: Ee, Cis Only) - Sony HCD-GR8 Service Manual

FM Polar Adjustment (RX90: EE, CIS only)

Connection 1:
FM RF SSG
75 Ω coaxial
Carrier frequency : 69 MHz
: 1mV (60dBµ) (at 75 Ω open)
Output level
Modulation : AUDIO 1 kHZ, 10kHz deviation
Connection 2:
AF OSC
FM RF SSG
Audio 31.25 kHz
external
modulation
terminal
Carrier frequency : 69 MHz
: 1mV (60 dBµ) (at 75 Ω open)
Output level
Modulation : AUDIO 31.25 kHZ, 10 kHz deviation
(EXTERNAL MODULATION)
Adjustment Location :
EE, CIS:
[TCB BOARD] (Component Side)
• Abbreviation
EE: East European model
CT1701, L1701, TP1701
Sub carrier peak
Adjustment
set
FM ANTENNA terminal
(75 Ω )
75 Ω coaxial
set
FM ANTENNA terminal
(75 Ω )
RV41
AM tuned level
Adjustment
RV1701, TP1701
Sub carrier level
Adjustment
RV1702, TP1702
VCO Adjustment
Procedure :
1. Set the modulation of FM RF SSG to AUDIO 1 kHz, 10 kHz
deviation according to "Connection 1".
2. Tune the set to 69 MHZ.
3. Adjust the RV1702 so that the reading of frequency counter
connected to TP1702 becomes within 31.25 kHz ± 0.05
kHz.(VCO adjustment)
4. Then record the reading of the level meter connected to TP1701
5. Set the modulation of FM RF SSG to AUDIO 31.25 kHz, 10
kHz deviation according to "Connection 2".
6. Tune the set to 69 MHz.
7. Set the CT1701 to be mechanical center.
8. Adjust the L1701 so that the reading of the level meter con-
nected to TP1701 become maximum.
Then adjust the CT1701 so that the reading of the level meter
connected to TP1701 becomes maximum. (SUB CARRIER
PEAK Adjustment)
9. Adjust the RV1701 so that the level at the moment becomes
14dB higher value than the level recorded in step 4. (SUB CAR-
RIER LEVEL Adjustment)
RV41
TM1
IC41
RV42
RV1701
L1701 CT1701
(FILTER) TP1701
IC1701
TP1702
(VCO)
RV1702
– 38 –
RV42
FM tuned level
FE1
Adjustment
LEVEL METER
+
–
FREQUENCY COUNTER
+
–