Re: Letting the smoke out on Palettas

Much has been written about dimmers parked ON.  All of it is to advise not using devices that need clean power on parked dimmers.  Among all the other issues, could be having the rack control  electronics set to adjust and regulate to incoming line voltage, which could cause the dimmer to potentially reduce output voltage as it compensates.  Sensors can have this function turned off in the CEM, not sure about Strand.

In any event, once you get the fixtures repaired, I'd find another power source, or swap dimmers to relays or constant breaker modules (if you can get the gear from Strand).

It sounds like you've created an "On" profile in the console (0% > 100%, 100% > 100%), and that's really not a good way to do this.

Aside from the possibility of accidentally changing the assigned dimmer curve (eg by loading a different show file), this isn't the same as a dimmer set to Switched or Always-On.

Many modern dimmers support automatic regulation of voltage to reduce the effect of small spikes and dips in the mains supply on tungsten lamps, and this causes the supply to the fixture to be discontinuous whenever the mains supply is higher than the 'regulated' output target.
- Obviously if the supply voltage is lower than the target then the dimmer can't do anything about it.

If you wish to power a Selador fixture through a dimmer, then you should set the dimmer circuit to be a Switched or Always-On, Unregulated supply so that the dimmer controller knows your intentions and won't attempt any features designed for dimmable loads.

These modes are available in the majority of dimming systems, often named something like "Switched", "1/0", "Non-Dim", "Always On" etc.

Finally, it is worth noting that not all 'intelligent' fixtures (LED, moving light etc) can be powered in this way, and you should always check with the manufacturer of the fixture before powering them through any SCR dimming system.

Hi Jennifer,

It would be interesting to know exactly what smoked on the circuit boards in the fixtures. If you are comfortable opening them up yourself you can do so, if not you should contact your ETC dealer to get them back for repair. Narrowing it down to an area of the fixture might give us a clue as to what happened.

How old are these fixtures? Depending on age they may have a replaceable DMX chip, so if the smoke came from the DMX section of the circuit that might be something you could replace yourself.

One final thing to look at might be the wiring of the mains cords to the fixtures. I did come across a situation once with a cord which had a hot and ground swapped that produced a similar effect..

-Tom

Thanks!

The Paletta manual indicates that they would run just fine on dimmers whose profile has been modified to be, for all intents and purposes, a non-dim (switched), which is why we had no concerns about powering them in this fashion.

(Now, maybe we were living in a fool's paradise.)

For our units that do care (VLs, etc) we have true non-dims that we move around the C21 racks, as necessary (yes, Strand has all that gear.)

We just added to our inventory of dual non-dim, dim/nondim, and nondim/dim drawers and so the Palettas will be powered by true nondims as of this season.

That will ease worries that the modified waveform could cause damage.

I don't believe the C21s behave like Sensors, but I don't have any experience with Sensors...

The output from our profiled dimmers ranges from 114v - 122v rms, which is within the stated range of 100 - 240VAC/50-60Hz.

Again, the way we've got it set up the dimmers are always full on and won't dim unless someone selects Channel 1003 and fades it to 100% in a count.  

My crew knows not to do that.

Typos can happen but in this case we weren't writing cues.

We had just hung and circuited (we have a rep plot, so no changes there) and turned on the console to begin focus.

We had no cues in the board.

We believe our system to be fairly idiot-proof until they invent a better idiot.

But obviously something happened...

FWIW - our VLs in one specific position also had a mind of their own. (They are plugged into true non-dims, and always have been.)

We're working on that one.

To me this has all the earmarks of a control issue, but we have another (12) 42" and (13) 11" Palettas which are unaffected and are controlled by dimmers profiled the same way and in the same channel as the ones with issues.

Thanks for the feedback and please let me know if any of the above info gives you additional ideas.

I appreciate getting insight from others in the industry.

Thanks for this info.

You are right about the possible problems that could arise, although as I've said, we've pretty much done what we can to cover our bases.

Re: loading a different show with a different curve - we run with a rep plot and default patch. All shows are built off of that patch, so it is unlikely, although certainly not impossible, for the profile to be changed.

As you've probably read in a post I just sent, we are aware of what instruments should and shouldn't be jury-rigged in this fashion, but the manual that came with the Palettas seemed to state that these units would be okay with this system.

In any case, it's not a clear cut case of 'power poison' - three quarters of the Palettas, some powered by the same dimmer, work just fine.

Hi Tom,

From what I have been told the smoke came from the vents between the second and third cells of the affected 4-cell units. The majority of the affected units (4) were the 42", but we did lose one 11".

I have to check serial numbers, but our oldest units were only purchased back in August of 2010.

Our newest batch came in February, 2011.

I may be inclined to open up the 11" to satisfy my morbid curiosity, but overall I'll more likely send them out for repair.

I'm just curious to see if anyone else has seen anything similar to what I've described and, if so, what was the cause.

Anyway, I've I've said - thanks for all the insights.

Jennifer