1.4-Mhz Demodulation Circuit Adjustment - Sony HXCU-100 Service Manual

6-6-2. 1.4-MHz Demodulation Circuit Adjustment

Preparation
. Disconnect the coaxial cable from the connector CN3901
on the DPR-300 board, and then connect the FM signal
generator to CN3901.
. FM signal generator settings
Carrier frequency: 1.4 MHz
AF frequency: 1 kHz
_15 dBm
Output level:
?3 kHz
Dev:
Tuning Adjustment
1. Equipment: Oscilloscope
Test Point: TP1502 (E-6)/DPR-300 board
GND: E1501 (F-6)/DPR-300 board
Adjusting Point: 1LV1502 (E-6)/DPR-300 board
A = 1.3 ?0.2 V
Specifi cation:
2. Equipment: Audio analyzer
(Unbalanced, high-impedance,
HPF: 400 Hz, LPF: 20 kHz)
Test Point: TP1503 (E-6)/DPR-300 board
GND: E1501 (F-6)/DPR-300 board
Adjusting Point: 1LV1503 (E-6)/DPR-300 board
Specifi cation: Minimize the distortion.
3. Equipment: Audio analyzer
(Unbalanced, high-impedance,
HPF: 400 Hz, LPF: 20 kHz)
Test Point: TP1503 (E-6)/DPR-300 board
GND: E1501 (F-6)/DPR-300 board
Adjusting Point: 1LV1502 (E-6)/DPR-300 board
Specifi cation: Minimize the distortion.
4. Repeat steps 2 and 3 to minimize the output carrier
level.
Check that the distortion is 0.4% or less.
5. Check that the DC level "A" of terminal TP1502 on
the DPR-300 board is 1.3 ?1.0 V.
6-12 (E)
A=1.3 ? 0.2 V
GND
HXCU-100