Roland OD-20, Service Notes

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15
OD-20(T)
7. DAC check
1.
Set the TYPE volume to BD-2/DS-1.
2.
Connect an oscilloscope to OUTPUT, and check the output waveform
(DSP oscillation).
fig.1
(200mV/div, 1msec)
3.
Press MEMORY SELECT. The MEMORY 4 LED will go dark, and the
output signal will be muted. Verify that the signal is less than -67 dBm
(IHF-A).
4.
Connect an oscilloscope to LINE OUT/PHONES, and check the L and R
output waveform (DSP oscillation).
fig.2
(200mV/div, 1msec)
5.
Press MEMORY SELECT. The MEMORY 4 LED go dark, and the output
signal will be muted. Verify that the noise for L and R is less than -68 dBm
(IHF-A).
8. DSP thru check
1.
Set the TYPE volume to HM-2/MT-2.
2.
Connect an oscillator to INPUT, and input a 344 Hz, 50 mVp-p square
wave.
3.
Connect an oscilloscope to OUTPUT, and check the output waveform.
fig.3
(500mV/div, 1msec)
9. Analog mute check
1.
Set the TYPE volume to BOOST/LEAD.
2.
Connect an oscillator to INPUT, and input a 344 Hz, 50 mVp-p sine wave.
3.
Connect an oscilloscope to OUTPUT, and check the output waveform.
fig.4
(20mV/div, 1msec)
4.
Press MEMORY SELECT. The MEMORY 4 LED will go dark, and the
output signal will be muted. Verify that its level is less than -77 dBm
(IHF-A).