[SML] Dimmers won't turn off

[Dan Sheehan]

On Thu, Aug 27, 2015 at 12:11 PM, nathan best via Stagecraft <
stagecraft at theatrical.net> wrote:

> I had a power outage recently and now certain lights won't turn off. My
> Sensor+ dimmer rack says those dimmers are receiving signal, but I'm not
> sending anything. I've even disconnected the DMX cable. I get no errors on
> the rack. Any thoughts?
>
> Nathan
>
OK, some thoughts, but I lack direct Sensor experience, so take with grain
of salt:

disconnecting the DMX cable could leave the inputs in an ambiguous state,
even (or especially !) if the terminator remains in place...
not sure what the Sensor will do in that case...

do other dimmers show no-signal with disconnected cable ?
if so, I'd suspect damage to the control module which shows false signal
presence

do other dimmers work OK when desk connected & running ?

like Dorian said, the power drive semiconductor device sometimes fails by
melting down into a conductive blob, which is uncontrollably full ON.
Don't think that's a likely result of a power outage, esp on several
channels,
more likely result of a shorted load which the protection didn't act fast
enough.
(are Sensors "supposed" to be short-circuit-proof ?)

are all affected channels on the same control module ?

swap affected dimmer module with one not so affected,
if fault moves with dimmer, it's in the dimmer,
if known-good dimmer now shows fault it's in the controller.

-- 
...Dan Sheehan
Fixer of things that break
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