7. ADJUSTMENT PROCEDURE

 

7-1 Power supply check

1. Positive ripple.

Should be no more than 2mVp-p.

Set oscilloscope vertical gain at 10mV/cm and check that power supply ripple is 2mV or less.

2. Negative ripple.

Same as positive, should be no more than 2mVp-p.

7-2 Pitch adjustment

1. VCO-1.

Perform adjustment with synthesizer controls at "normal setting" (Scale=8, Waveform= N Master Tune, Pitch, and all other knobs at "0"). See figure 1.

a. Play C-3 (high C) on the keyboard and adjust the high trim 1 semi-fixed screw until you obtain the correct tuning as indicated by WT-10A (connected to the SIG OUT jack).

b. Play key C-1 and adjust the low trim 2 semi-fixed screw.

c. Repeat steps a and b as many times as necessary until both are tuned to the correct pitch.

 

 

 

d. Check the tuning of C-1, C-2, and C-3 on the WT-10A meter to make sure pitch deviation is with +2 cents for each.

e. Change the scale to 32', 16', 8', and 4' and check the tuning of all four C keys to make sure that the pitch deviation of each is within +10 cents.

7-3 KBD CV adjustment

Use a 4-1/2 digital voltmeter to measure the KBD

CV OUT signal.

a. Measure output voltage first when you play key C-3, then when you play key C-2. The output voltage for C-3 should be exactly half that for C-3. Adjust the KBD CV high tim 3 semi-fixed screw as necessary so that C-2 produces half the voltage of C-3.

b. Measure C-2 and then C-1 in the same way. Adjust the KBD CV low trim 4

semi-fixed screw as necessary so that C-2 produces exactly half the voltage of C-3.

c. Repeat steps a and b as many times as necessary until the output voltage of each of C-1, C-2, and C-3 is exactly half that of the next.

 		   

7-4 VCF Fc adjustment

Connect a frequency counter to the Sig out jack.

1. VC LPF

Refer to the settings shown in figure 2. Set the Fc knob at "5", and the LPF PEAK knob at "10". Then adjust the Q semi-fixed screw as necessary so that the LPF oscillation frequency is 500Hz.