Sony WRT-807B, Service Manual

Page: 27 / 64

3-11
WRT-807B (U/CE)
Procedure
n
Perform the checking with the AF input connector (CN303/
CN-1868 board) short-circuited.
(1) Connect the spectrum analyzer to the antenna connector
(CN305) with SMA-BNC (J) connector (and RF con-
version connector).
(2) Connect a jumper wire between the TONE terminal
(land) and GND by soldering as shown in the above
“Connections”.
(3) Set the spectrum analyzer as follows:
CENTER FREQUENCY (fc):
CE57 model ; 770.000 MHz
CE62 model ; 810.000 MHz
CE67 model ; 850.000 MHz
U30 model ; 578.125 MHz
U42 model ; 650.125 MHz
U62 model ; 770.125 MHz
U66 model ; 794.125 MHz
REFERENCE LEVEL : 20 dBm
FREQUENCY SPAN : 200 kHz (20 kHz/DIV)
RBW (resolution band width) : 3 kHz
VBW (video band width)
: 1 kHz
ATT : 20 dB
(4) Decrease gradually the DC output voltage of the DC
regulated power supply and confirm that the battery
alarm signal turns on (The BATT indicator on the LCD
will blink.) at 1
±
0.1 V.
(5) Check that level difference between carrier frequency
(center frequency level) on the spectrum analyzer and
tone signal is with in 29
±
1 dB.
2. Frequency check
Connections
(For connecting the DC power supply, refer to the “Prepara-
tion” on page 3-2.)
Procedure
n
Perform the checking with the AF input connector (CN303
CN-1868 board) short-circuited.
(1) Connect the modulation analyzer to the antenna connec-
tor (CN305) with SMA-BNC (J) connector (and RF
conversion connector), and connect the frequency
counter to the AF OUT connector on the modulation
analyzer.
(2) Set the modulation analyzer as below;
MEASUREMENT : FM
MEASUREMENT RANGE :
±
10 kHz
HPF : 4 kHz
LPF : >20 kHz
DE EMPHASIS : OFF
(3) Set the DC output voltage of DC power supply to 1
±
0.1V so that battery alarm signal goes on. (The BATT
indicator on the LCD will blink.)
(4) Check that frequency counter (resolution: 0.1 Hz) read-
ing is 32.782 kHz
±
1 Hz.
(5) After the checking, remove (unsolder) the jumper wire
between TONE terminal (land) and GND on the MB-
860 board (B-side).
fc
32.782 kHz
V : 10 dB/div
H : 20 kHz/div
29 ± 1 dB
20 dBm
Modulation
analyzer Frequency
counter
MB-860 board (B side)
CN305
TONE
GND
Jumper wire
Connect a jumper wire between TONE land
and GND land by soldering.
(TONE signal : OFF)
SMA-BNC (J) connector with
RF conversion connector