Sony TC-730 Service Manual page 33

Procedures
(1) Play back the Ist tone (400 Hz) of SONY
alignment tape (J-19-F2).
Test Setup:
x
LINE OUT jack
16.Playback S/N
Ratio
Measurement
(2) Note the VTVM reading.
(3) Remove the alignment tape.
(5) Place the unit in the FWD or REV mode without
the tape threaded.
(6) Note the VTVM reading.
(7) Make sure that the level difference between
step (2) and step (6) is more than 48 dB.
Switch Setting:
MONITOR switch .............5-6.
Specification:
more than 48 dB in both FWD and REV modes
(8) Reverse the power plug to the AC outlet and
repeat the step (1) through the step (6).
Make sure that the level difference is also more
than 48 dB.
17.Erase Ratio
Measurement
Deliver a 1 kHz signal of -50 dB(2.45 mV)to the
MIC jack.
(3) Record the signal on the tape, noting where the
reading begins for a later reference.
Disconnect the audio oscillator.
MIC jack eee
aa antT Rewind a half of the recorded tape.
Terminate the MIC jack with a 300 22 resistor.
Erase the tape by recording with no input signal.
LINE OUT jack (8) Rewind again to the beginning of the recording.
Place the unit in the playback mode.
Control/Switch Setting:
Play back the tape, reading the VTVM, and make
sure that the difference between the two parts is
more than 60 dB, and that the level fluctuation
width is within 5 dB.
If not, check the tape path adjustment.
*Record volume control
specified position on page 25
*MONITOR switch ...............
Specification:
*Erase ratio.......-.---- more than 60 dB
*Level fluctuation width ....... within 5 dB
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