Sony MDRRF-950 Service manual
MDR-RF950
SERVICE MANUAL
Ver 1.0 1998. 06
MDR-RF950 is headphones
in MDR-RF950RK.
SPECIFICATIONS
US Model
Canadian Model
TABLE OF CONTENTS
1. GENERAL ................................................................. 2
2. DISASSEMBLY ......................................................... 3
3. ELECTRICAL ADJUSTMENTS
3-1. Checking/Adjusting Receiving Frequency ..................... 5
3-2. Checking/Adjusting Degree of Modulation
of Main Carrier (L + R) .................................................. 6
3-3. Checking/Adjusting Separation...................................... 7
4. DIAGRAMS
4-1. Printed W iring Boards..................................................... 11
4-2. Schematic Diagram......................................................... 13
5. EXPLODED VIEWS................................................ 15
6. ELECTRICAL PARTS LIST ............................... 17
Notes on chip component replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be damaged by heat.
WIRELESS STEREO HEADPHONES
MICROFILM
This section is extracted from
instruction manual.
SECTION 1
GENERAL
– 2 –
• This set can be disassembled in the order shown below.
SECTION 2
DISASSEMBLY
SET FRONT PLATE ASSY
Note: Follow the disassembly procedure in the numerical order given.
RX-BASE BOARD SW BOARD
HANGER COVER (L)
FRONT PLATE ASSY
4
Remove two solders
of driver lead.
3
front plate assy
RX-BASE BOARD
2
hanger cover (R)
2
three screws
(P2
1
×
6)
3
Remove four solders
of leads.
4
RX-BASE board
ear pad
1
two screws
(P2
1
two screws
(P2
×
6)
×
10)
3
Remove three solders
of leads.
– 3 –
SW BOARD
y
)
2
screw (P2 × 6)
3
switch support
5
SW board
1
two head bands
4
head cushion ass
HANGER COVER (L)
1
two screws
×
10)
(P2
1
two screws
×
6)
(P2
3
Remove two solders
of battery lead.
2
hanger cover (L
– 4 –
SECTION 3
ELECTRICAL ADJUSTMENTS
Note:
1. The adjustments should be performed in the order given.
2. The transmitter (TMR-RF950R) already checked and adjusted should be used.
3-1. Receiving Frequency Check and Adjustment
Preparation:
AF OSC
+
+
–
–
DC voltmeter
oscilloscope
+
–
ATT
+
–
600
AUDIO IN (Lch)
1 kHz 316 mVrms
TMR-RF950R
Transmitter
Ω
MDR-RF950
5 m
Headphones
[RX-BASE board] – Conductor Side –
Procedure:
1. Set the channel of the transmitter to CH2.
2. Turn OFF the noise filter switch on the transmitter.
3. Enter 1 kHz 316 mVrms signal only to the Lch on the transmitter.
4. Place the transmitter away from the headphone (MDR-RF950) more than 5 m.
5. Set the volume control (RV301) on the RX-BASE board to the minimum position.
6. Set the tuning control (RV302) on the RX-BASE board to the center position.
7. Connect a DC voltmeter and an oscilloscope between IC301 pin @¡ and ground on the RX-BASE board.
8. After confirming that demodulated 1 kHz waveform (about 13 mV) appears on the oscilloscope, check that the DC v oltmeter indicates
DC1 V to 1.2 V.
9. If demodulated 1 kHz waveform does not appear on the oscilloscope, or if the voltage is out of the specif ied value, adjust the air-core
coil (L301) on the RX-BASE board so that the demodulated 1 kHz waveform appears on the oscilloscope, and under this condition,
adjust finely the air-core coil (L301) so that the DC voltmeter indicates DC1.1 V.
10. Finally, check that signals are receiv ed when the channel is changed ov er to CH1/CH3 on the transmitter , then when the tuning control
(RV302) on the RX-BASE board is rotated.
Adjustment Location: RX-BASE board (See page 9.)
– 5 –
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