Note

All revised 901 B Oscillator printed circuit cards (91-079) have tracking pots (P2). 1. Slide oscillator out with power cord connected and allow 30-minute warm-up period. 2. Set frequency RANGE switch at 4 ft. on each oscillator. 3. Set frequency VERNIER control at seven on each oscillator. 4. On the 901A Oscillator Controller, set FIXED CONTROL VOLTAGE switch on zero and oscillator frequency VERNIER control on zero, 5. Strike highest note with a keyboard controller. 6. Using sawtooth output...

Range Switch Scaling

If using a Model 950 or 951 Keyboard, depress and hold C3. If a Model 952 Keyboard is used, depress and hold C5. Adjust (A) for 2093Hz (or two octaves above reference). B. Switch RANGE to 32'. Adjust (5) for 130.8Hz (or two octaves below reference). C. Check all RANGE positions for 0 - 1 Hz. C. Apply a unison (523Hz) - 2dB to OdB square wave to the SYNCH, input. Rotate FREQUENCY pot clockwise and counterclockwise from 0. Locking range should be at least 2 semitones on...

Retracking Of 901b Oscillators With Serial Numbers Under 1912

Reduce the FIXED CONTROL VOLTAGE controls on the oscillator so that the total is 0. The oscillator frequencies will, of course, be lowered five octaves, and may be out of tune with one another. Pick oscillator which is producing the lowest frequency. This oscillator is the reference oscillator, and will not require a tracking resistor. Connect a resistance substitution box as the tracking resistor to each of the other oscillators in turn. Find resistors that bring the oscillators in tune with...

Tuning Procedure

The 901A adjustments should be set only after the 901B oscillators have been adjusted to track properly as described for the 901B and the 901A has been allowed to run in the cabinet with the 901 B s for at least ten minutes. The instruments should be at room temperature. 1. Set the two FIXED CONTROL VOLTAGE controls on the 901A panel to 0. 2. Connect an accurately calibrated voltage source, which is stable to within 0.1 , to one of the control inputs of the 901 A. For instance, the pitch...

951 Keyboard Tuning

The keyboard has two adjustments to be made. The scale adjustment adjusts the current source so that the total drop across the resistor string is 5.000 volts. The range adjustment fixes the lowest key at zero volts. Adjustments are made with the external range and scale controls on the five mark. 2. Adjust the range setting with the trimpot. If adjustment cannot be made within the range of the trimpot, it may be necessary to short one or both of the two resistors in series with it. 3. Adjust...

Probable Cause

(3) OVP triggering with Q2, Q3, CR6 shorted (4) CR1, CR2, CR3, CR4, C1 or C2 shorted (1) Possible overload or current limit adjust R11 improperly adjusted (should be set for 120 of full load current prior to feedback) (2) Possible OVP triggering (check setting of R22) (4) C1, CR5, R4( C3, Q1, C4, R11, R14, R15, CR8 or C6 shorted (2) Q2, Q3, CR6, R3 or R16 shorted (2) SCR1, Q4, CR7, R21 or R22 shorted (1) SCR1, R17, Q4, CR7, R21 or R22 open (2) Inadequate heat sinking or heat sink bolted to...

11

Connect the 956 Ribbon Controller to the test rack. Patch TRIGGER output of the 956 to the 911 Envelope Generator, then to the 902 Voltage Controlled Amplifier. Connect SIGNAL OUTPUT of a voltage controlled oscillator to the 902 SIGNAL INPUT. Connect 902 SIGNAL OUTPUT to a monitor amplifier and speaker. Connect PITCH output to the voltage controlled oscillator CONTROL INPUT. Touch TRIGGER bar on the 956. Oscillator should be heard. Adjust the 911 and 902 for a square envelope. Set SCALE to 1...

Notes

L.Set wirewound trimpots R17 and R25 to mid-position. 2. Set FIXED CONTROL VOLTAGE to 6, FREQUENCY RANGE to 2 and REGENERATION to 0. 3. Using a dc voltmeter, check the voltages at R35 and R39. Both levels will be approximately 1.0 volts. Adjust R40 (zero trimpot on filter board) for approximately the same voltage at R35 and R39. 4. Connect DC VOLTMETER across R23 (470 ohms) and adjust 2.0 volt LEVEL trimpot (R24) for 2.0 volts. Disconnect DC VOLTMETER after adjusting. 5. Apply a 20kHz Odb...

General

The 905 Reverberation Unit utilizes a dual spring-type acoustic delay line to produce a succession of decaying echoes of an audio signal. A single panel control determines the ratio between the amounts of reverberated and non-reverberated signals that appear at the output jack. The front panel control does not alter the characteristic decay time of the echoes, since this is a function of the delay line itself. Instructions for mounting and connecting of power, and input and output...

904a Voltage Controlled Lowpass Filter Test Procedure

L.Set wirewound trimpots R17 and R25 to mid-position. 2. Set FIXED CONTROL VOLTAGE to 6, FREQUENCY RANGE to 2 and REGENERATION to 0. 3. Using a dc voltmeter, check the voltages at R35 and R39. Both levels will be approximately 1.0 volts. Adjust R40 zero trimpot on filter board lor approximately the same voltage at R35 and R39. 4. Connect DC VOLTMETER across R23 470 ohms and adjust 2.0 volt LEVEL trimpot R24 for 2.0 volts. Disconnect DC VOLTMETER after adjusting. 5. Apply a 20kHz Odb sinewave to...

Contents

TITLE PAGE SYN 2A 993-042141 Figure 1 Console 3 993-042644 Figure 2 Console 3A 993-042239 Figure 3 Control Panel Mixer 3 4A 993-042185 Figure 4 Console 35 993-042184 Figure 5 Console 901A 993-042645 Figure 6 Oscillator 901B 993-042646 Figure 7 Oscillator 901C 993-042647 Figure 8 Output 902 993-041813 Figure 9 Voltage Controlled 903A 993-041818 Figure 10 Random Signal 904A 993-041805 Figure 11 Voltage Controlled Low Pass Filter 13 904B 997-041807 Figure 12 Voltage Controlled...