Sony MB-806A, Service Manual

Page: 34 / 82

3-8 MB-806A (CE)
WRU-806A (CE, AU)
(5) Adjust the RF OUTPUT (Output level) of the signal
generator so that Signal to Noise ratio is 34 dB
±
5 dB
( S/N; 34 dB
±
5 dB) under the “ (1) S/N check ”.
(6) Turn
1
RV205 (tuner unit) slowly counterclockwise to
be the DC voltage of the TP201(NOISE) terminal
(land) change “L” (about 0 V).
(7) Adjustment
Specification: DC voltage of the TP201 (NOISE)
terminal (land) change from “L”(about
0 V) to “H”(about 4.8 V) level.
Adjustment:
1
RV205/RF-92 board (tuner unit 1)
Turn
1
RV205 slowly clockwise for
adjustment.
Step 2:
Tuner
[2]
to
[6]
adjustment
When the WRU-806A Tuner Unit is installed in the Tuner
[2]
(Tuner unit 2) to Tuner
[6]
(Tuner unit 6) of the MB-
806A, perform the adjustments from the procedure (1) to
(6) of “ Step 1: Tuner
[1]
(Tuner unit 1) adjustment” on
the respective tuner unit that are installed in the MB-806A.
When performing the above described adjustment change
the following details as shown below of the “Step 1: Tuner
[1]
(Tuner unit 1) adjustment”.
Tune
[1] →
Tuner
[2]
,
[3]
,
[4]
,
[5]
, or
[6]
Step 3:
After completing adjustment, turn off the MB-806A power
switch and perform the followings.
(1) Remove the tuner unit from the MB-806A.
(2) Remove the lower side case lid from the tuner unit,
and unsolder the wire ( 80 mm long) from the TP201
(NOISE) terminal (land).
(3) Attach the upper and lower side case lids to the tuner
unit, and insert the tuner unit to the slot of the MB-
806A.
3-2-2. Overall Characteristics Check
Perform the overall characteristics check according to the
following procedure.
Procedure
1. Output level check
↓
2. S/N check
↓
3. Frequency characteristic check
↓
4. Distortion check
↓
5. RF Level indicator check
↓
6. AF Level indicator/AF indicator check
↓
7. Muting level/RF indicator check
↓
8. BATT indicator check
↓
9. Tone squelch check
↓
10. DC + 9 V OUT voltage check
Equipment and Tools
.
Signal generator
. Audio analyzer
. Mic amp (Noise mete) with A-weighted filter
.
Function generator
.
Oscilloscope
. DC current meter
. DC cut fixture (See “How to make DC cut fixture” on
page 3-1.)