Case Files / No. 001 · Closed
Sequential Pro-One
Both oscillator chips replaced with current CEM3340 rev G, op-amps and audio driver renewed, then calibrated and scaled to factory spec.
| Make | Sequential |
|---|---|
| Model | Pro-One |
| Year | — |
| Category | Synthesizers |
| Service | 02 Restoration |
| Status | Closed |
Received
A Sequential Pro-One with the J-wire keyboard, due for a proper overhaul rather than a quick clean.
Work performed
- Replaced both oscillator ICs with CEM3340 rev G chips — current production, not 35-year-old stock.
- Most of the component-level work centered on Oscillator A: its timing capacitor, sync transistor, and pulse-width pot were all replaced.
- Replaced both LM348 op-amps and the 5532 audio output driver.
- Cleaned and adjusted the J-wire keyboard and cleaned the keyboard bus bar.
- Calibrated the VCA and keyboard, then tuned and scaled to factory spec. Checked the audio output and the CV/gate inputs.
- Refinished the wood end cheeks.
Result
Tuned, scaled, and calibrated to factory specification, with every oscillator, keyboard, and CV path checked.
Parts
| Part | Qty |
|---|---|
| CEM3340 rev G | 2 |
| LM348 | 2 |
| NE5532 | 1 |
| OSC A timing capacitor | — |
| OSC A sync transistor | — |
| OSC A pulse-width pot | — |