Roland ME-25 - D;A Conversion Checks; PHONES and OUTPUT L;R Output Tests

16
Feb. 2010 ME-25
5. D/A Check
1. Insert plugs into the OUTPUT L/MONO, R and PHONES jacks.
* Correct waveforms are not displayed unless all connections are made to the
OUTPUT L/MONO, R and PHONES jacks. Be sure shielded cords or jack
adapter plugs are inserted.
2. On the oscilloscope, set Channel 1 to 0.5 V/div, Channel 2 to 0.5 V/div,
and Time to 1.0 ms/div.
3. Input the PHONES output to the oscilloscope.
4. Verify that dA appears on the 7-segment LED display and that both the
triangular LEDs to the left and right of the 7-segment LED display light
up.
fig.test5-1.eps
5. Verify that the PHONES output value is between 850 and 930 mVp-p.
fig.test5-2.eps
6. Press [EXIT] and verify that the triangular LEDs to the left and right of
the 7-segment LED display go dark.
fig.test5-3.eps
7. On the oscilloscope, set Channel 1 to 0.1 V/div, Channel 2 to 0.1 V/div,
and Time to 1.0 ms/div.
8. Verify that the output value from the PHONES is 180 mVp-p or less.
fig.test5-4.eps
9. Change the input to the oscilloscope from PHONES to OUTPUT L, R.
10. On the oscilloscope, set Channel 1 to 0.5 V/div, Channel 2 to 0.5 V/div,
and Time to 1.0 ms/div.
11. Verify that nothing is output from the OUTPUT L, R.
fig.test5-5.eps
12. Press [EXIT] and verify that the triangular LEDs to the left and right of
the 7-segment LED display light up again.
13. Verify that the OUTPUT L, R output values are between 850 and 930
mVp-p.
fig.test5-6.eps
14. Detach the plug from OUTPUT R jack.
Verify that the OUTPUT L waveform changes as shown below.
fig.test5-7.eps
15. Insert the plug into OUTPUT R jack and detach the plug from the
PHONES jack.
Verify that the OUTPUT L, R waveforms change as shown below.
fig.test5-8.eps
16. Press [EXIT] to move to the next test.