Yamaha CS-30 Service Manual page 34

CS-30(S/£ 1001 ~)
SEQ Circuit Board
1. Clock Pulse Oscillator Circuit
Turn the CLOCK/MANUAL (PSW10) switch to CLOCK and turn the CLOCK SPEED volume (PVR1) to
S as far as it will go. Make sure that the frequency is 0.1 ± 0.01Hz at TP1. If not, adjust it by turning
VR2J . Then, turn the CLOCK SPEED volume fully to F position and adjust (VR l) until 30 ± 3Hz is
obtained. Repeat this adjustment until both S and F levels are both satisfied. LED indicator must glow
in accordance with the frequency.
2. Sequencer Circuits
A. Step Circuit
a. After turning the CLOCK/MANUAL (PSW10) switch to CLOCK, STEP (PSW1) selector to 8 and
NORMAL/KBD (PSW11) to NORMAL respectively, rotate the CLOCK SPEED volume (PVR1) by
about 1/3 of its full extent and depress START/STOP button. The LED indicator should glow to
indicate that the steps are shifted from 1 to 8 in sequence.
b. Turn the STEP (PSW1) switch to [n] position and the step must be changed to 1 to [n] from 1 to 8.
B. START/STOP Circuit
After turning the switches as mentioned in paragraph A—(a) above, press START/STOP button ON
(+15V input is applied to terminals SP/ST ('X)—4)). The LED indicator will go off the moment the
START/STOP button is depressed and will start from step 1 immediately after the switch is turned
ON again.
When CLOCK/MANUAL switch (PSW10) is turned to MANUAL position, the timing step will be
halted and it should be shifted step by step turning the START/STOP button ON and OFF alter¬
nately.
C. Pitch Circuit
After turning the switches as mentioned in paragraph A—(a), rotate each PITCH volume from 1 to 8
(PVR2 to 9) fully in the counterclockwise direction. Adjust (V R 3. so that the voltage level at
terminal Qo (C§>—4) is 0 ± 50/jV. Similarly, when all PITCH volumes are turned fully in the clockwise
direction, 2 ± 0.002V should be obtained at the terminal. With an arbitrary setting of each PITCH
volume of 1 to 8, a voltage between 0 and +2V in accordance with the setting should be obtained.
D. KV Buffer Circuit
a. Insert an open plug into KEY VOLT—IN receptacle (J5) on the rear panel and short KV ( .1.-8)
across G terminal. When NORMAL/KBD switch (PSW11) is turned to KBD position, the voltage at
TP6 must be 0 ± 50/iV. If not, adjust it by means of (VR
4
].
b. Withdraw the open plug, clear the short circuit and set PITCH 1 (PVR2) volume to the center
position. When PITCH volumes 2 to" n' (PVR3 to *n') are fully turned in the clockwise direction,
+2 ± 0.002V with the PITCH 1 timing and
+4
± 0.3V with the timing of PITCH 2 to [n] should
appear in Qo ( '3 -4) terminal.
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