Boss DD-3A - Adjustments; Adjusting High End of Clock Frequency (Minimum Delay Time)

8
May 2002
ADJUSTMENTS
* Adjusting the clock frequency for delay time.
1. Adjusting the high end of clock frequency (Adjusting the minimum delay time)
a. Set the VR3(D.TIME knob) to the min (fully-ccw).
b. Connect the oscilloscope to R26(1k ohm resister) or pin 5 (or pin 6) of IC3 (HD14066BP).
c. Adjust RT1 (1kB potentiometer) on MT BOARD for T=12.5±0.5uS(Fig.1).
In some types of products, turning the RT1 continuously clockwise may once go outside the adjustable range and reenter there.
Therefore, at the start, turn the RT1 fully counter-clockwise, then slowly turn it clockwise.
When the adjustable range is reached, stop turning it, then begin adjustment.
2. Adjusting the high end of clock frequency (Adjusting the minimum delay time)
a. Set the VR3(D.TIME knob) to the max(fully-ccw).
b. Connect the oscilloscope to R26(1k ohm resister) or pin 5 (or pin 6) of IC3 (HD14066BP).
c. Adjust RT2 (47kB potentiometer) on MT BOARD for T=50±2uS(Fig.2).
fig.1
fig.check3
22
21
23
5
3
4
2
1
678
9
14
1516
17
13
11
12
25
10
1819
20
IC3
R26RT1RT2
MAIN BOARD
View from part side
VR3(D.TIME)