Electrical Adjustments - Sony MDX-C670 Service Manual

TEST MODE
This set have the test mode function. In the test mode, FM Auto
Scan/Stop Level and AM (MW) Auto Scan/Stop Level adjustments
can be performed easier than it in ordinary procedure.
<Set the Test Mode>
1. Set the "power select" switch (S702) is "ON" position.
2. Turn ON the regulated power supply. (All LEDs on the set lights
up, and the clock is displayed.)
Note: Press the OFF button, if the clock is not displayed.
3. Push the preset 4 button.
4. Push the preset 5 button.
5. Press the preset 1 button for more than two seconds.
6. Then the display indicates all lights, the test mode is set.
<Release the Test mode>
1. Push the OFF button.
MD SECTION
MD section adjustments are done automatically in this set.
TUNER SECTION
Cautions during repair
When the tuner unit is defective, replace it by a new one because
its internal block is difficult to repair.
FM Auto Scan/Stop Level Adjustment
Setting:
SOURCE button: FM
FM RF signal
generator
0.01 µ F
Carrier frequency : 98.0 MHz
: 22 dB (12.6 µ V)
Output level
Mode : mono
Modulation : 1 kHz, 22.5 kHz deviation (30%)
Procedure:
1. Set to the test mode. (See page 12).
2. Push the SOURCE button and set to FM.
Display
REG
3. Push the preset 3 button.
Display
REG
SECTION 4

ELECTRICAL ADJUSTMENTS

0dB=1µV
antenna
terminal
set
SHUF1
SHUF1
4. Adjust with the volume RV2 on TU1 so that the "FM" indica-
tion turns to "FM0" indication on the display window.
But, in case of already indicated "FM0", turn the RV2 so that
put out light "0" indication and adjustment.
Adjustment Location: See page 14.
FM Stereo Separation Adjustment
Setting:
SOURCE button: FM
FM RF signal
generator
0.01µF
Carrier frequency : 98.0 MHz
Output level : 70 dB (3.2 mV)
Mode : stereo
Modulation : main: 1 kHz, 33.75 kHz deviation (45%)
sub: 1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot: 7.5 kHz deviation (10%)
Procedure:
FM Stereo
signal generator
output channel
L-CH
R-CH
R-CH
L-CH
L-CH Stereo separation: A-B
R-CH Stereo separation: C-D
The separations of both channels should be equal.
Specification: Separation more than 30dB
Adjustment Location: See page 14.
– 12 –
Display
REG
SHUF1
antenna
terminal
10 k Ω
set
LINE OUT
Level meter Level meter
connection reading (dB)
A
L-CH
B
L-CH Adjust RV4 on TU1
for minimum reading.
C
R-CH
D
R-CH Adjust RV4 on TU1
for minimum reading.
VTVM
+
–