Roland JD-XA, Service Notes

Page: 33 / 35

33
Jul. 2015 JD-XA
3. Pulse Width Check
This verifies the Duty ratio of pulse wave of oscillator.
+————————————————+
|A1-OSC1: PW 10%|
|Press [ENTER] |
+————————————————+
1.
Verify that the pulse width shown in the figure is shorter than 0.3 ms .
fig.test-a-3-1.eps
2.
Press
Enter
.
A screen like the one shown below is displayed.
+————————————————+
|A1-OSC1: PW 50%|
|Press [ENTER] |
+————————————————+
3.
Verify that the pulse width shown in the figure is in the range of 0.9 to
1.4 ms .
fig.test-a-3-2.eps
4.
Press
Enter
.
Execution advances to the check of the next wave form.
5.
For A1-OSC2 , A2-OSC1 , A2-OSC2 , A3-OSC1 , A3-OSC2 , A4-OSC1 and
A4-OSC2 , verify in the same way as steps
1
through
4
.
6.
Press to advance to the next test item.
4. VCF1 Check
This verifies the circuit of VCF1 (4-pole OTA Filter).
+————————————————+
|A1-VCF1: CUT Min|
|Press [ENTER] |
+————————————————+
1.
Verify that the frequency of the signal shown in the figure is lower than
40 Hz .
fig.test-a-4-1.eps
2.
Press Enter .
A screen like the one shown below is displayed.
+————————————————+
|A1-VCF1: CUT Max|
|Press [ENTER] |
+————————————————+
3.
Verify that the frequency of the signal shown in the figure is higher than
8 kHz
.
fig.test-a-4-2.eps
4.
Press
Enter
.
A screen like the one shown below is displayed.
+————————————————+
|A1-VCF1: RES Min|
|Press [ENTER] |
+————————————————+
5.
Verify that no signal is output, and then press Enter .
Execution advances to the check of the next wave form.
6.
For A2-VCF1 , A3-VCF1 and A4-VCF1 , verify in the same way as steps
1
through
5
.
7.
Press to advance to the next test item.
N egative W idth
N egative W idth