There are two CE versions of a CMd processor for Legacy Unison systems: the standard (ETC Part Number 7083A1004-5), and the high voltage (7083A1004-5HV). What is the difference between the two? Can I only use the -5HV variant in a 230 / 277V rack?
There are actually no differences in the dimming engine circuitry between the two variants, so either processor should power up and work in a 230 / 277V rack.
The only difference between the two variants of processor are the LCD screen used. The original variant, the -5, used an LCD that was found to occasionally be susceptible to voltage spikes at 277V. Those could cause the LCD to stop working, although the other circuitry in the processor would be unaffected. That LCD was replaced with a more robust version in the -5HV variant of the processor.