30/05/2026
Roland SH-101 – Structural restoration, CPU recovery, and high-precision calibration
This SH-101 arrived in the lab in critical condition, with clear signs of past non-standard repairs and evidence consistent with an old liquid-related event. Several ICs had already been replaced, suggesting a historical failure that affected the power and logic sections, including key voice circuitry around the Roland IR3R03 area and the CEM3340.
A major issue was the internal harness. The original mainboard-to-CPU wiring had been rebuilt with unsuitable wire and adhesive, and multiple solder points near connectors were compromised. Several IC sockets appeared to be donor parts, with stressed pads and unreliable contact. Before any calibration could be trusted, the platform had to be rebuilt for mechanical and electrical stability.
We rebuilt all critical inter-board connections using new, stable wiring designed to avoid movement-related intermittency. The power section was returned to correct configuration by removing adapted parts and replacing non-compliant components, restoring a stable +5 V reference rail required by the CPU and logic functions. The CPU pins showed oxidation; the pins were cleaned and the CPU was reinstalled using a new gold-contact socket. Damaged traces and heat-stressed areas were reconstructed and reinforced, applying the same method to the Roland and CEM sections to ensure continuity and stable voice behavior. The ON/OFF switch assembly and pitch bend board were also restored to eliminate intermittent behavior.
Because this is an early-series unit, calibration required rebuilding the correct CEM3340 reference network. A non-matching reference configuration was preventing stable scaling. Once restored, calibration became consistent and repeatable.
Final scale check shows excellent accuracy: the two-octave ratio test (F3 to F5) reached 99.957% ratio accuracy, equivalent to about -0.74 cents over two octaves. Less than 1 cent error over two octaves is a rare result on an analog SH-101 and approaches the consistency typically associated with more rigid digital-referenced systems.
