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MICROFILM
SERVICE MANUAL
WIRELESS STEREO HEADPHONES
US Model
Canadian Model
SPECIFICATIONS
MDR-RF930
MDR-RF930 is headphones
in MDR-RF930K.
Notes on chip component replacement
· Never reuse a disconnected chip component.
· Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
Ver 1.0 1998. 06


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­ 2 ­
SECTION 1
GENERAL
This section is extracted from
instruction manual.


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HOUSING (R) ASSY, HANGER (R)
9 two screws
(P2
× 8)
2 screw
(B1.7
× 4)
1 ear pad
3 driver ( L-CH )
8 housing (L) assy
7 ball shaft holder
6 screw
(P2
× 6)
4 battery cover
5 hanger (L)
4 two screws
(P2
× 6)
4 two screws
(P2
× 10)
7 ball shaft holder
8 housing (R) assy
6 screw
(P 2
× 10)
5 hanger (R)
2 screw
(B1.7
× 4)
1 ear pad
3 driver (R-CH)
· This set can be disassembled in the order shown below.
SECTION 2
DISASSEMBLY
HOUSING (L) ASSY, HANGER (L)
HOUSING (R) ASSY, HANGER (R)
BATTERY CASE
RX BOARD
SET
Note: Follow the disassembly procedure in the numerical order given.
HOUSING (L) ASSY, HANGER (L)


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RX BOARD
4 two head bands
5 suspender assy
1 two screws
(P2
× 10)
2 battery case
3 tension spring
4 push (1 key) SWITCH
6 two head bands
7 suspender assy
1 RX board
3 RX shield plate
5 tension spring
2 two screws (B1.7
× 4)
BATTERY CASE


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­ 5 ­
Note:
1.
The adjustments should be performed in the order given.
2.
The transmitter (TMR-RF930) already checked and adjusted should be used.
3-1.
Receiving Frequency Check and Adjustment
Preparation:
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-RF930) 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 voltmeter 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 specified 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 received when the channel is changed over 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.)
SECTION 3
ELECTRICAL ADJUSTMENTS
AF OSC
ATT
AUDIO IN (Lch)
1 kHz 316mVrms
600
Trans-
mitter
Head-
phones
+
­
+
­
TMR-RF930
5 m
MDR-RF930
+
­
+
­
oscilloscope
DC voltmeter
[RX-BASE board] ­ Conductor Side ­