Sony WRT-847A, Service Manual

Page: 21 / 54

3-5 WRT-847A/847B
3-2-4. Reference Frequency Deviation
Adjustment
Equipment and Tools
DC power supply
DC output voltage: + 3.0
±
0.1 V dc
DC ammeter
Audio analyzer
Modulation analyzer
RF adjusting cable (Part No. J-6402-390-A)
RF conversion connector (Part No. J-6402-490-A)
AF input cable (Part No. J-6407-010-A)
Adjustor (Part No. 7-721-052-81)
Connections
(For connecting the DC power supply, refer to the “Prepara-
tions” on page 3-2.)
Switch and Control Setting
First, Perform the same setting as described in “4. Switch and
Control Setting during Adjustment and Checking,” on page 3-
3, then perform the following setting:
RF power setting:“H” (= 50 mW)
Procedure
(1) Input 1 kHz, _ 55 dBV ( _ 52.8 dBm) signal to the AF
input connector (CN301/MB-914 board) with AF input
cable.
(2) Connect the modulation analyzer to the antenna connec-
tor (CN402) with RF adjusting cable (and RF conver-
sion connector).
Set the modulation analyzer as below;
MEASUREMENT: FM
MEASUREMENT RANGE: AUTO or
±
10 kHz
(manual operation)
HPF: 50 Hz
LPF: 15 kHz or 20 kHz
DE EMPHASIS: 50 u s
(3) Adjust 1 RV303 so that the frequency deviation for the
modulation analyzer reading meets the following speci-
fication.
Specification: Frequency deviation = Maximum
Adjustment: 1 RV303/MB-914 board (B side)
(4) Adjust 1 RV304 so that the frequency deviation for the
modulation analyzer reading meets the following speci-
fication.
Specification: Frequency deviation = Maximum
Adjustment: 1 RV304/MB-914 board (B side)
(5) Adjust 1 RV402 so that the frequency deviation for the
modulation analyzer reading meets the following speci-
fication.
Specification: Frequency deviation =
±
5 kHz
±
0.1 kHz
Adjustment: 1 RV402/RF-96 board (A side)
(6) After the adjustment has been completed, perform the
“3-2-5. Maximum Frequency Deviation Adjustment”.
DP-341 board RF-96 board
Modulation
analyzer
RF adjusting cable
Oscilloscope
AF OUT RF IN
AF input cable
Oscillator
Level meter
Audio analyzer
CN301
RF conversion connector
CN402
MB-914 board (A side)
RV402
1
MB-914 board (B side)
RV301
RV303 RV304
1 1
1