The Emax keeps working data alive with a backup battery on the digital board. Like most 1980s gear, that NiCad cell can leak over time and corrode nearby traces — the single most common long-term failure on these units.
Symptoms: lost settings on power-down, green/white corrosion around the battery, intermittent boot failures.
Procedure: power off and discharge the unit; desolder the old cell; neutralise and clean any corrosion with isopropyl alcohol and inspect for lifted/eaten traces (repair with bodge wire as needed); fit a fresh battery — a modern coin-cell holder is a common serviceable replacement. Verify settings now persist across power cycles.
Always confirm the exact cell, voltage and polarity against the service-manual schematics before fitting. (Community-sourced procedure — verify for your board revision.)