Service manual

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TO ADJUST . . . FOLLOW THIS PROCEDURE . . .
Oscillator Tuning
(Without Equipment)
"Visualign"
Turn all MIXER switches off. Set MIXER VOLUMES at 1.
Turn on MAIN OUTPUT switch and set OUTPUT VOLUME to 8.
Set ATTACK and DECAY times to 0, SUSTAIN to 10.
Turn FILTER MODULATION and KEYBOARD CONTROL
switches off. Set EMPHASIS and AMOUNT OF CONTOUR to 0.
Set PITCH WHEEL to center, TUNE control to 0, RANGE
switches to 2 ft., WAVEFORM switches to TRIANGLE.
Turn OSCILLATOR MODULATION switch off, and
OSCILLATOR 3 CONTROL switch on. Set OSCILLATOR 2 and
3 FREQUENCY controls to mid-position. Connect a short patch
cord from the HIGH MAIN OUTPUT jack to EXTERNAL
SIGNAL INPUT jack. Turn on A-440 and rotate EXTERNAL
INPUT VOLUME control slowly clockwise until the OVERLOAD
light is just visible. Turn OSCILLATOR 1 Mixer switch on.
Depress low "A" key and hold, OVERLOAD light should be
blinking. Depress and hold high "A" key. Adjust OSCILLATOR 1
Range Trimpot (on oscillator board) for slowest possible blink rate.
Depress and hold low "A" key. Adjust OSCILLATOR 1 Scale
Trimpot (on oscillator board) for slowest possible blink rate.
Monitor the output with headphones while tuning. Repeat this
procedure for OSCILLATOR 2 and 3. Then check tracking
between any two oscillators.
Octave Range Trimmer Turn OSCILLATOR 1 Mixer switch on and set RANGE to 2 ft.
Turn on A-440. Depress and hold second "A" key from the bottom.
Adjust TUNE control for zero beats. Switch RANGE to 8 ft.
Depress same key and adjust Octave Range
trimpot (on oscillator
board) for zero beats.
Noise Level Noise level is factory-set to yield -5dB maximum in the white
position. If the level becomes low it may be increased by
counterclockwise rotation of the Noise Level Trimpot
(on Power
Supply board). It may be necessary to use an offset screwdriver to
reach this trimpot.
VCA Balance Turn all MIXER switches off. Connect headphones and set
VOLUME fully CW. Connect a jumper from point "A" on the
Filter Board (see Fig. 3) to point "A" on the oscillator board
(see Fig. 1). While listening to the headphones, adjust the 2nd
VCA Balance trimpot (on the filter board) for the minimum audio
signal. Depress and hold a key. Adjust the lst VCA Balance
trimpot for minimum audio signal. Remove the jumper.