Test of Quadrature PC for use as freq. shifter ..................................................... 1. Plug outputs J and K into scope 2. Adjust R2 to midpoint of turn 3. Adjust R1 for exactly 1.768 Volts A.C ( 10mV) at pad K using a voltmeter switched to its AC range. Something wrong if the resulting oscillation is not 160 Herz plus/minus 30%. 4. Adjust R4 for for 0.000 Volts D.C. (remember to switch voltmeter to DC) at pad K 5. Adjust R5 for for 0.000 Volts D.C at J. 6. Adjust R2 for exactly 1.768 Volts A.C at pad J (AC voltmeter) 7. Repeat 4. and 5. 8. Adjust R3 for volt per octave response. Input VC at pad A. ..................................................... Quadrature Oscillator as separate module 1. Do all steps above, except that the natural frequncy will be 5 Herz, plus minus 30%. But input inte VC input to raise the Freq. so that AC volt can be read. 2 Check that the outputs at L and M fall within the range of plus/minus 2.3 Volts peak down to plus/minus 1.4 Volts peak. If out of range, suspect R17, 18, 19, 20, 21, 22, 39, 40. If these are ok, replace 3280 (the 3280 is still "good" if any output is seen, and can be saved for other uses). 3. Plug gate into hold input, and watch for hold. Note: "1.4 Volts peak" as seen on scope means that the top peak of the wave is 1.4 volts above the baseline, and trough 1.4 Volts below the line, i.e 2.8 Volts peak to peak.