Boss Roland GT-8 Service Notes page 20

Dec.2004
12. INPUT A/D
Input a rectangular wave, and observe the output waveform with the
oscilloscope.
INPUT: Rectangular wave, 400 Hz, 40 mVp-p
Press the [WRITE] button.
fig.12-01test
12.INPUT A/D
[IN----->OUT]
Confirm that the following type of waveform is output.
fig.006.eps
Rotate the OUTPUT VR from MAX to MIN and to MAX again, and confirm
that the amplitude of the waveform changes smoothly as the knob is turned.
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to "13. DSP INT0."
13. DSP INT0
Press the [WRITE] button; the DSP's internal oscillator-generated pitch
interrupt signal is checked.
If an error occurs, the type of error is indicated in the display, and if operation
is normal, "OK!" is displayed.
If OK:
fig.13-01test
13.DSP INT0
--- OK ! ---
If an error occurs:
fig.13-02test
13.DSP INT0
---ERROR!---
Press the PARAMETER [>] button to proceed to "14. Noise(IN->OUT)."
14. Noise(IN->OUT)
INPUT -> A/D -> DSP -> D/A -> OUTPUT
(Connect noise meter and observe)
Note: Check with both L(MONO) and R jacks.
When the OUTPUT jacks are used individually, the left and right channel
signals are mixed internally, so be sure to insert a blank plug in the R channel
output when measuring the L(MONO) channel; when checking the R channel,
insert the blank plug in the L(MONO) channel jack.
Press the [WRITE] button.
fig.14-01test
14.Noise(IN>OUT)
[IN----->OUT]
OUTPUT Level:MAX
Confirm that the residual noise is no more than -86.0 dB (JIS-A).
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to "15. Noise(LOOP)."
22
15. Noise(LOOP)
INPUT -> A/D -> DSP -> D/A -> SEND -> RETURN -> A/D -> DSP -> D/A -
> OUTPUT
(Connect noise meter and observe)
Note: Check with both L(MONO) and R jacks.
When the OUTPUT jacks are used individually, the left and right channel
signals are mixed internally, so be sure to insert a blank plug in the R channel
output when measuring the L(MONO) channel; when checking the R channel,
insert the blank plug in the L(MONO) channel jack.
Press the [WRITE] button.
fig.15-01test
15.Noise(LOOP)
[RETURN->OUT]
OUTPUT Level:MAX
Confirm that the residual noise is no more than -84.0 dB (JIS-A).
Press the [EXIT] button and then press the PARAMETER [>] button to proceed
to "16. Calibrate EXP."
16. Calibrate EXP
Set the EXP pedal minimum and maximum values and the EXP pedal switch
threshold.
Press the [WRITE] button.
fig.16-01test
16.Calibrate EXP
Set Pedal to MIN
Bring the EXP pedal back completely, release, and press the [WRITE] button.
When set, "OK!" appears in the display, which subsequently shows the
following.
If operating properly:
fig.16-02test
16.Calibrate EXP
Set Pedal to MAX
If an error occurs:
fig.16-03test
16.Calibrate EXP
- Area Over ! -
Press the EXP pedal fully forward, release, and press the [WRITE] button.
When set, "OK!" appears in the display, which subsequently shows the
following.
fig.16-04test
16.Calibrate EXP
Threshold:
Rotate the [PATCH/VALUE] dial to "6" and press the [WRITE] button.
When set, "OK!" appears in the display.
This completes Test mode.
Press the PARAMETER [>] button to proceed to "17. Factory Load."
Press the [EXIT] button to quit Test mode.
16.Calibrate EXP
<-->
press [WRITE]
<--> 16.Calibrate EXP
press [WRITE]
6