Sony MB-806A Service Manual page 32

3. Noise squelch adjustment
Equipment and Tools
* 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)
DC cut fixture (See the "How to make DC cut fixture"
on page 3-1.)
°
Preparation
Before the adjustments, turn off the POWER switch of the
MB-806A, and perform the following.
1. Remove the case cover of the MB-806A.
2. Remove the tuner unit (WRU-806A) to be adjusted
from the MB-806A. Refer to " Section 1. Operating
Instructions " for removal.
3. Remove the upper and lower side case lids of the tuner
unit (WRU-806A) to be adjusted.
4. Solder a wire (80 mm long) to the TP201 (NOISE)
terminal (land) on the RF-92 board, and take out the
free side of the wire (80 mm long) to the upper side of
the tuner unit as shown below.
TP201(NOISE)
terminal(land)
Lead wire
Tuner unit
(Lower side)
(80 mm long)
Tuner unit
(Upper side)
5. Attach the lower side case lid to the tuner unit, and
insert the tuner unit to the slot of the MB-806A.
Connection
Same as " 2. Output level adjustment ".
MB-806A (CE)
WRU-806A (CE, AU)
Switch and Control Setting
Front panel (Tuner (1])
Channel setting:
CE62 model; Group 00, 6301 channel (806.125 MHz)
CE69 model; Group 00, 6933 channel (858.125 MHz)
AU66 model; Group00, 6701 channel (799.250 MHz)
Muting: OFF
Rear panel
ATT(ANTENNA A, B) switch: 0 dB
Procedure
Step 1: Tuner [1] (Tuner unit 1) adjustment
The adjustment procedures describe that the WRU-806A
(to be adjusted) is installed into the Tuner [1] slot on the
MB-806A.
(1) S/N check
Perform the " 2. S/N Check " of Section 3-2-2. Overall
Characteristics Check.
When checking the S/N at 0 dBUVEMF (= —113dBm),
note the ANNTENA A or B IN connector which -
shows the better S/N.
Connect the signal generator to the ANTENNA A (or
B) IN connector which showed the better S/N atthe
input of 0 dBuVeEmrF ( = ~113 dBm) under "(1) S/N
check".
Connect the oscilloscope to the wire ( TP201 terminal)
as shown below.
(2
~~
(3
~
RV205
DC range setting
Tuner unit
(Upper side)
(4
~~
Set the signal generator as follows;
Signal generator setting
FREQUENCY (carrier frequency):
CE62 model; 806.125 MHz
CE69 model; 858.125 MHz
AU66 model; 799.250 MHz
RF OUTPUT (Output level): 0 dBUVEMF
=-113 dBm)
MODULATION (Moduation frequency): 1 kHz
DEVIATION (Frequency deviation): £5 kHz