Electrical Adjustments - Sony MDR-RF450 Service Manual

Note :
1. Use transmitter with check and adjustment already completed.
2. The transmitter section adjustments should be completed before
performing the headphones section adjustment.
3. On adjusting the headphones section, use the transmitter as a
jig.
Headphones Transmitter
MDR-RF430
TMR-RF450R
MDR-RF450
Setting :
AF OSC
L-CH (J403)
1kHz 316mVrms (–7.8dB)
ATT
600 Ω
1. Feed a signal to jig (transmitter) and connect a power supply to
DC IN 9V jack (J404).
Receive frequency check and adjustment
1. Set the transmitter channel to CH2.
2. Set the transmitter noise filter SW to OFF
3. Input a signal of 1kHz 316mVrms to onl
(J403).
4. Place transmitter and headphones at a distance of more than 5m
apart.
5. Set the VOL (RV301) to MIN.
6. Position RX boar d TUNING VOL (RV302) to the center
7. Connect a digital voltmeter (DC range) and an oscilloscope be-
tween IC301 pin @¡ and GND.
8. First check to make sure that a demodulated waveform of 1kHz
(appr oximatel y 13mVrms) is outputted to the oscilloscope
chec k to make sure the DC v
9. If a demodulated waveform of 1kHz is not outputted to the os-
cilloscope or if the DC level is not within the range specified
above, adjust the RX board L301 so that a demodulated wave-
form of 1kHz is outputted to the oscilloscope and while the wave-
form is outputted, further fine adjust the L301 so that the DC
voltmeter reading is DC 1.1V
10. When completed, make sure signals can be received when switch-
ing the transmitter channel to CH1 or CH3 by turning RX board
TUNING VOL (RV302).
Connection points and Adjustment Location :
SECTION 2

ELECTRICAL ADJUSTMENTS

Jig
Transmitter
J404
power supply
(DC 11V)
.
y the transmitter L-c
.
, then
oltmeter reading is DC 1–1.2V
.
RX board (See page 5)
Separation check and adjustment
1. Set the transmitter channel to CH2.
2. Set the transmitter noise filter SW to OFF
3. Input a signal of 1kHz 316mVrms to onl
(J403).
4. Connect an digital voltmeter (AC range) and oscilloscope to
the L-ch speaker outputs (both sides of MDD01).
5. Receive signals b
6. Adjust the VOL (RV301) so that the RX boar
outputs (both sides of MDD01) are 155mVrms.
7. Connect an digital voltmeter (AC range) and oscilloscope to
the R-ch speaker outputs (both sides of MDD02) and measure
the voltages.
8. At this time, check to make sure the level separation of L-ch
and R-ch speaker outputs is more than 20dB. If the separation
is less than 20dB,
output is minimal, then check to see if the level separation of L-
ch and R-ch speaker outputs is more than 20dB.
9. Input a signal of 1kHz 316mVrms to onl
(J402).
10. Adjust the VOL (RV301) so that the RX boar
outputs (both sides of MDD02) are 155mVrms.
11. Connect an digital voltmeter (AC range) and oscilloscope to
the L-ch speaker outputs (both sides of MDD01) and measure
the voltages.
12. At this time, check to make sure the level separation of L-ch
and R-ch speaker outputs is more than 20dB.
Connection points and Adjustment Location :
h
.
– 4 –
.
y the transmitter L-c
y turning the TUNING VOL (RV302).
d L-c h speaker
turn R V303 on the RX boar d so that the R-c
y the transmitter R-c
d R-c h speaker
RX board (See page 5)
h
h
h