Read Sony MDX-C7890R Service Manual online
– 14 –
SECTION 4
ELECTRICAL ADJUSTMENTS
TEST MODE
This set have the test mode function. In the test mode, FM Auto
Scan/Stop Level and MW Auto Scan/Stop Level adjustments can
be performed easier than it in ordinary procedure.
Scan/Stop Level and 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 (S700) is “A (ON) ” position.
2. Turn ON the regulated power supply. (All LEDs on the set
1. Set the “power select” switch (S700) is “A (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
1. Push the
[OFF]
button.
2. Return the “power select” switch (S700) to initially set posi-
tion.
MD section adjustments are done automatically in this set.
Cautions during repair
When the tuner unit is defective, replace it by a new one be-
cause its internal block is difficult to repair.
cause its internal block is difficult to repair.
Note:
Adjust the tuner section in the sequence shown below.
1. FM Auto Scan/Stop Level Adjustment.
2. FM Stereo Separation Adjustment.
3. MW Auto Scan/stop Level Adjustment.
4. RDS S-Meter Adjustment.
1. FM Auto Scan/Stop Level Adjustment.
2. FM Stereo Separation Adjustment.
3. MW Auto Scan/stop Level Adjustment.
4. RDS S-Meter Adjustment.
FM Auto Scan/Stop Level Adjustment
Setting:
[SOURCE]
button: FM
MD SECTION
See the adjustment location from on page 16 for the ad-
justment.
justment.
TUNER SECTION
0 dB=1 µV
Carrier frequency : 98.0 MHz
Output level
Output level
: 22 dB (12.6
µ
V)
Mode
: mono
Modulation
: 1 kHz, 22.5 kHz deviation (30%)
FM RF signal
generator
0.01
µ
F
set
antenna jack (J1)
Procedure:
1. Set to the test mode.
2. Push the
1. Set to the test mode.
2. Push the
[SOURCE]
button and set to FM.
Display
3. 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.
But, in case of already indicated “FM0”, turn the RV2 so that
put out light “0” indication and adjustment.
Display
Adjustment Location: See page 16.
FM Stereo Separation Adjustment
Setting:
[SOURCE]
button: FM
Procedure:
FM Stereo
Level meter
Level meter
signal generator
connection
reading (dB)
output channel
L-CH
L-CH
A
B
R-CH
L-CH
Adjust RV4 on TU1
for minimum reading.
R-CH
R-CH
C
D
L-CH
R-CH
Adjust RV4 on TU1
for minimum reading.
L-CH Stereo separation: A-B
R-CH Stereo separation: C-D
The separations of both channels should be equal.
R-CH Stereo separation: C-D
The separations of both channels should be equal.
Specification: Separation more than 30 dB
Adjustment Location: See page 16.
SHUF
REG
SHUF
REG
Carrier frequency : 98.0 MHz
Output level
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%)
19 kHz pilot: 7.5 kHz deviation (10%)
FM RF signal
generator
0.01
µ
F
set
antenna jack (J1)
+
–
–
speaker out terminal
level meter
4
Ω
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