Sequential Circuits Pro One Synth

To Do:

  • Install New Keybed 

  • Clean Switches, Potentiometers and Contacts

  • Replace Electrolytic Capacitors (Start w/Power Supply)

  • Replace Tantalum Capacitors 

  • Check the Regulators (replace if needed)

  • Add heat sink to 5v regulator 

  • Replace Power Cord with modern one

  • Replace Fuse and Holder 

  • Update AC Power Supply section wiring as in video 

  • Calibration and Tuning

***DAC Scaling and Tuning and Amplifier Balance elements only accessible when PCB is removed from instrument Chassey****

Tuning section in Technical Manual Here

Video Walkthrough of Tuning



Recapping The Pro-One 

(Use Nichicons or Panasonic)

BLOG POST

VIDEO


SCHEMATIC


  • C163, 164, 165, 166 — 2.2 uF Tantalum, 10v & 25v  (In the Power Supply)

+Replace with electrolytic —  go with 25v , 35v or 50v on all 4 (if possible 105 degree C). (MAY WANT TO ADD A 100nF CERAMIC ACROSS THE CAPS)

  • CC167, C168 - PSU Reservoir (2 Big Ones) - 2 x 2200uF, >25v, 105degC. 

+ Replace with 105 degree C (Long Life Nichicons?), 25v

  • C153 — CPU Reset — 1 uF 10V, Aluminum Electrolytic

+Replace with same specs


AUDIO GRADE

  • C131 — Noise Gen. — 2.2 uF, 15v, Aluminum Electrolytic (Audio)

  • C132, C133 — Noise HPF — 2.2 uF, 50v, Aluminum Electrolytic (Audio)

  • C143 — VCF Output — 2.2 uF, 15v, (Audio)

+Replace all with same specs, Audio Grade


Pro One Manuals:

Technical


Operation