Adjustment - Sony WRR-800A Service Manual

3. Noise squelch adjustment
Equipment and Tools
. DC power supply: +9 Vdc
. Signal generator
. Audio analyzer (level meter, distortion meter)
. Mic amp (Noise meter)
. Oscilloscope
. Adjuster (0.4 x 1.3 mm) : (Part No. 7-221-652-81)
Preparation
Before the adjustments, turn off the POWER switch of the
WRR-800A, and perform the followings.
1. Remove the case cover of the WRR-800A.
2. Remove the tuner unit from the WRR-800A.
3. Remove the upper and lower side case lids of the tuner
unit.
4. Solder a wire (80 mm long) to the TP201(NOISE)
terminal (land), and take out the free side of the wire
(80 mm long) to the upper side of the tuner unit as
below.
TP201(NOISE)
terminal(land)
Solder
Lead wire
(80 mm long)
Tuner unit
(Lower side)
5. Attach the lower side case lid to the tuner unit, and
insert the tuner unit to the slot of the WRR-800A.
Connection
Same as " 2. Output level adjustment ".
Switch and Control Setting
Channel setting:Group 00, 6701 channel
(799.250 MHz)
VOL. Control: MAX
Muting: OFF
3-6
Lead wire
Tuner unit
(Upper side)
Procedure
Step 1: S/N check
Perform the " 2. S/N Check " of Section 3-2-2. Overall
Characteristics Check.
When checking the S/N at 15 dBuV
note the ANNTENA A or B IN connector which shows the
better S/N.
Step 2: Adjustment
(1) Connect the signal generator to the ANTENNA A (or
B) IN connector which showed the better S/N at the
( = _98 dBm) under "Step 1.
input of 15 dBuV
EMF
S/N check".
Set the signal generator as follows;
(2) Connect the oscilloscope to the wire (TP201 terminal)
as shown below.
(3) Signal generator setting
FREQUENCY (Carrier frequency): 799.250 MHz
RF OUTPUT (Output level): 15 dBuV
MODULATION (Moduation frequency): 1 kHz
DEVIATION (Frequency deviation): ± 5 kHz
RV205
Tuner unit
(Upper side)
(4) Adjust the RF OUTPUT (Output level) of the signal
generator so that Signal to Noise ratio is 20 dB ± 5 dB
( S/N; 20 dB ± 5 dB) under the " Step 1. S/N check ".
(5) Turn 1RV205(tuner unit) slowly counterclockwise to
be the DC voltage of the TP201 (NOISE) terminal
(land) change "L" (about 0 V).

(6) Adjustment

Specification: DC voltage of the TP201 (NOISE)
terminal(land) change from "L"(about
0 V) to "H"(about 4.8 V) level.
Adjustment: 1RV205/RF board (tuner unit)
Turn 1RV205 slowly clockwise for
adjustment.
( = _98 dBm) ,
EMF
EMF
(= _98 dBm)
Oscilloscope
DC range setting
WRR-800A