VCS3 / Synthi A Point by Point Quick Setup Procedure


1. Check Mains voltage setting.
2. Plug in Card A only.
3. PSU Switch on. Adjust PR2 for +12 volts.
4. PSU Adjust PR1 for -9 volts.
5. Plug in Cards B and C.
6. PSU Recheck +12V and -9V.
7. REVERB Adjust Pr3 so that mixing occurs above 2 on the Reverb Mix knob.
8. REVERB Check the voltage control of reverb mix.
9. O/P Adjust PR4 and PR5 for zero residual signals.
10. O/P Check the tracking of Level knobs 4-5-6.
11. ENV Set Trapezoid speed to 65Hz with PR12
12. ENV Set PR13 clockwise.
13. ENV Adjust PR8 for minimum residual signal.
14. ENV Adjust PR13 until signal just reappears, then back off to zero.
15. ENV Check that maximum On time is at least 4 seconds.
16. ENV Check that maximum Decay time is at least 15 seconds.
17. ENV Check that recycling occurs with Off set at 5.
18. ENV Check that recycling does NOT occur with Off set abaove 7.
19. ENV Check that Trigger functions and does not jam.
20. FILT With filter in oscillation and Frequency control on 5, set PR6 for 261Hz.
21. FILT Check that Response control gives filtering below 5 and oscillation above.
22. FILT Check the shape of the oscillating Sine wave.
23. RM Adjust PR10 for fundamental rejection on A residual signal.
24. RM Adjust PR9 for 1st harmonic rejection on A residual signal.
25. RM Adjust PR11 for fundamental rejection on B residual signal.
26. RM Adjust PR8 for 1st harmonic rejection on B residual signal.
27. RM Check for frequency doubling when both inputs are the same.
28. I/P Check both channels for correct gain on both Hi and Lo inputs.
29. OSC1 Adjust PR17 for best sine wave shape.
30. OSC1 With Frequency on 6 set PR15 for 261Hz.
31. OSC1 With Frequency on 8 add R290 (sot) to achieve 2088Hz.
32. OSC1 Recheck last two steps.
33. OSC1 Check both waveforms.
35. OSC2 Set PR20 half-way.
36. OSC2 Pad shape resistors R227/R228 to achieve correct shapes.
37. OSC2 With Frequency on 6 set PR19 for 261Hz.
38. OSC2 With Frequency on 8 add R291 (sot) to achieve 2088Hz.
39. OSC2 Recheck last two steps.
40. OSC1/2 Adjust PR20 to achieve oscillator tracking to 2kHz.
41. OSC3 Pad shape resistors R261/R262 to achieve correct shapes.
42. OSC3 With Frequency on 8 set PR21 for 63Hz.
43. NOISE Select a (transistor) diode for good bandwidth and level.
44. NOISE Adjust PR2 for around 3 volts p-p noise.
45. NOISE Check the operation of the noise colour control.
46. METER Set signal zero on the meter itself and check operation.
47. METER Adjust PR14 for control voltage zero.
48. JOYSTICK Adjust vertical for equal excursions on meter.
49. JOYSTICK Adjust horizontal for equal excursions on meter.

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