Juno-106 Voice & Chorus Restoration
The Roland Juno-106 is a masterpiece of polyphonic analog synthesis, but it is plagued by a specific failure in its 80017A VCF/VCA voice chips. This project involved a comprehensive restoration of the voice board and the legendary analog chorus circuit to return this unit to factory-fresh performance.
The "Acetone Bath" & Voice Calibration
The primary issue with the Juno-106 is the conductive epoxy coating used on the original voice chips, which eventually causes internal shorts. My restoration process addresses this at the component level.
Voice Chip Chemical Stripping
I perform a controlled chemical stripping of the 80017A chips to remove the failing protective coating. This "un-shucking" process preserves the original Roland silicon while eliminating the source of crackling and hanging notes.
Precision Tuning & Scaling
After restoration, each of the six voices is meticulously calibrated for resonance, filter cutoff, and VCA bias to ensure perfect polyphonic uniformity across the keybed.
Chorus Circuit Noise Reduction
The Juno's chorus is iconic but often suffers from "bucket-brigade" clock noise or static. I serviced the BBD (Bucket Brigade Device) circuit, replacing aging electrolytic capacitors and adjusting the bias and balance trimmers with an oscilloscope to achieve the lowest possible noise floor while maintaining that signature lush width.