Electrical Adjustments - Sony TMR-RF940R Service Manual

2. ELECTRICAL ADJUSTMENTS

Note:
• Perform countermeasure for distortion before adjustments.
Adjust and confirm the unit by following procedure shown below after this countermeasure.
• Please adjust the transmitter and the headphone together.
Procedure for Measurements and Adjustments
Lastly, we would like to explain the procedure for adjusting this model. As this model adopts a Stereo Modulation method called "FM-
FM", it is difficult to perform the adjustments with common measurement equipments.
The following adjustment should be performed with a spectrum analyzer.
Measurement of White noise level
1) Set the models and necessary equipments as shown in the figure1.
2) Observe the waveform of the oscilloscope. In case that a beat can be seen in the waveform, select a channel (CH1 or CH2) with less
beat.
3) Use the CCIR/ARM Filter for the noise meter and measure the white noise level. If the value is below –63 dBV (0.7 mVrms), the level
is acceptable.
AC adaptor
AC-E455D (supplied)
AC 230 V 50 Hz
Connect nothing to the plug
of noise filter.
Adjustment of Transmitter
Set the transmitter and a spectrum analyzer as shown below.
Observe the waveform on the spectrum analyzer
without Audio input signal into transmitter.
AC 230 V 50 Hz
AC-E455D (supplied)
noise filter
(supplied)
Figure 1.
spectrum analyzer
Connect nothing.
Figure 2.
– 3 –
1 m
Use supplied VOL MAX.
Ni-cd battery.
SP1 Lch
or
SP2 Rch
noise meter
Use CCIR/ARM filter.
ANT
oscilloscope