Section 3 Electrical Adjustments - Sony MDR-RF930 Service Manual

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:
AF OSC
ATT
+
+
–
–
DC voltmeter
oscilloscope
+
–
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
TMR-RF930
+
Trans-
–
mitter
600 Ω
AUDIO IN (Lch)
1 kHz 316mVrms
MDR-RF930
5 m
Head-
phones
[RX-BASE board] – Conductor Side –
– 5 –