SCR and
SSR dimmers dead-short fail in a constant on state, which is what this sounds like.
I could not find this particular Jands
dimmer system on their site, but am taking a guess it's a 12 pack non-modular system ? (I.E. the dimmers are not on individual or dual modular/swappable cards). I would open up the pack (cut mains power first) and swap the dimmer card to another location to determine if the problem migrates to another
DMX address. If the problem migrates, you have a blown pair of SCR's or one half of the SSR (SSR's are typically one power cube powering 2 circuits). If the problem crops up in the same output
circuit, then the trouble is not in the actual SCR pairs or the SSR. Next test would be to swap control modules between packs (don't worry about DMX addressing at this point, to see of the problem migrates with the card - if not, then the problem is external control,
etc.....
As David Fox at ETC told me, look for the simplest solution first.
Steve B.