Fixing a Real EMS Synthi 100

1. Synthi 100 Restoration Overview

The Synthi 100 is a rare and historically important instrument. After a detailed inspection, we are confident it can be returned to full working condition. Much of the groundwork has already been laid by previous owners, and the remaining tasks, while complex, are achievable with the right expertise and care.

2. General Condition and Approach

Many of the original components are still available or have modern equivalents, and the circuitry follows principles familiar to experienced engineers. The team has already assembled comprehensive documentation and has built connections with other Synthi 100 owners and experts, which will be invaluable throughout the restoration process.

While the project is ambitious, it is manageable. The restoration will focus on both preserving the instrument’s unique character and ensuring it is functional and safe for long-term use. A balance will be struck between maintaining original features and introducing careful updates where necessary.

3. Power Supply

The Synthi requires a complex set of power supplies. Only a few are currently installed, and those in place are outdated and potentially unsafe. These will be replaced with modern, reliable units that meet current safety standards. Proper grounding between all sections of the machine will also be established to reduce unwanted noise and ensure stable performance.

4. Control Surfaces

The main panels and control surfaces are in very good condition, thanks to earlier restoration work. Critical components like the knobs (potentiometers) have already been replaced with high-quality modern parts. Some original controls, such as sliders and switches, will be carefully cleaned and lubricated to restore full functionality. The patch matrixes are in good order, though some mechanical fixings will need replacing.

5. Wiring

The internal wiring of the Synthi is one of the most complex aspects of the restoration. Much of it will need to be replaced due to past damage and the limitations of the original design. The team will carefully map out the connections and use shielding techniques to reduce signal interference. This work will also address known design issues such as signal loss and crosstalk.

6. Keyboard

The twin keyboards require significant mechanical and electrical work. Surface issues are masking deeper problems that affect playability and calibration. All necessary repairs are within the capabilities of a skilled technician, and replacement parts are generally available.

7. Analogue Circuitry

A detailed review showed that around 40% of the analogue electronics are already functioning. The remaining circuitry will be repaired, followed by careful calibration to ensure the entire system performs as intended. Some elements will only reveal their condition once the machine is fully operational, so there will be ongoing diagnostic work as the project progresses.

8. Digital Circuitry

The Synthi’s digital systems, essentially a 1970s computer, represent the most technically demanding part of the restoration. Fortunately, all components needed to repair this system are still available, and the team already has custom tools that will support the process. The work will require expertise in early computer logic and will be carried out with great care to preserve original design intent.

9. Oscilloscope and Frequency Counter

These diagnostic instruments are essential to the Synthi’s operation. Both oscilloscopes will need full refurbishment, and the frequency counter requires repair to its high-voltage circuitry. These tasks will be undertaken by specialists familiar with vintage electronics.

10. Balancing Originality and Functionality

Throughout the restoration, the team will consider how best to preserve the character of the instrument while ensuring reliability. Some ageing components, though still functioning, will need to be replaced to prevent future failure. Others may be retained for their historical or acoustic value.

Where possible, original or originally-specified components will be used. In cases where those are unavailable, high-quality modern equivalents will be carefully selected. The modular nature of the Synthi also opens up possibilities for developing portable systems that can house its original circuit cards for performance and exhibition.

11. Looking Ahead

This restoration presents a rare and exciting opportunity. The Synthi 100 is not only a unique piece of musical history but also a powerful tool for creativity. The work being undertaken will ensure it remains usable, accessible, and inspiring for years to come. The team is committed to approaching the project with sensitivity, curiosity, and a deep respect for the instrument’s legacy.