Sony MDR-RF940R, Service Manual

Page: 14 / 14

– 4 –
Adjustment for Separation
Preparation:
Procedure:
1) Input a signal of 400 Hz 316 mVrms only to Lch of the adjusted transmitter.
2) Turn RV91 on the RX board so that the speaker out of Lch becomes 155 mVrms.
3) Turn RV61 on the RX board so that the speaker out of Rch becomes minimum.
4) At this time, confirm the separation between Lch and Rch should be over 18 dB.
5) Then, input a signal of 400 Hz 316 mVrms only to Rch of the transmitter.
6) At this time, confirm the separation between Rch and Lch should be over 18 dB.
Adjustment Location: RX Board
Confirmation without a spectrum analyzer
Please confirm the units by following procedure shown below.
Here a series of procedure which can be performed without a spectrum analyzer is introduced.
Tuning frequency confirmation
Preparation:
Procedure:
1) Input any signal including music into TMR-RF940R and place the unit the point where is far from MDR-RF940R and place the unit in
a location where is far from by 5 m.
2) Measure the DC voltage at the test point TP2 of RX board of MDR-RF940R.
This DC voltage corresponds to the S-curve voltage of FM detection characteristics as shown below.
If tuned frequency is in the area covered by AFC, the center voltage changes when CT41 (channel 1) CT42 (channel 2) is turned.
Adjustment Location:
AF OSC
ATT
input plug (Lch or Rch)
400 Hz 316 mVrms
600
Ω
Trans-
mitter
AC voltmeter
Head-
phones
speaker out (Lch or Rch)
+
–
+
–
+
–
TMR-RF940R
MDR-RF940R
AF OSC
ATT
input plug
AF signal or music
600
Ω
Trans-
mitter
DC voltmeter
Head-
phones
RX Board TP2
+
–
+
–
+
–
TMR-RF940R
5 m
MDR-RF940R
Sony Corporation
Personal A&V Products Company
9-923-238-81
98E0539-1
Printed in Japan © 1998. 5
Published by Quarity Engineering Dept.
(Shibaura)
Spec.
DC1.1
±
0.1 V
0
f
IC41
RV61
CT41
CT42
RV91
[RX Board] – Side A –
MDR-RF940R
PRINTED WIRING BOARD
• MDR-RF940R Service Manual page 5.
(Location F – H, 4 – 6)
[RX Board] – Side A –
DC voltmeter
+
–