When the main chip of this Kurzweil SP4-7 failed, the unit was destined for the scrap heap. However, the 76-key mechanical hardware was still excellent. Instead of discarding it, I gutted the dead electronics and transformed the original shell into a modern, standalone digital synthesizer. Cut the rear panel and sides to accommodate a 5" touchscreen and new I/O ports. Internal mounting hardware was modeled in Fusion 360 and 3D printed in PETG. An Arduino Mega manages the 76-key matrix, running the SeilerKeys open-source firmware to ensure precise velocity sensitivity and custom response curves. A Raspberry Pi 5 running Zynthian acts as the multi-engine synthesis motor (SF2, FM, Physical Modeling). Audio output is handled by a PCM5102 DAC, with plug-and-play support for external USB interfaces. The result is a professional-grade, self-contained workstation that bridges the gap between quality vintage hardware and modern open-source synthesis. https://youtu.be/NCz9auycRFU