Flickering Lighting

[royallark]

Hi,

 

I would really appreciate some advice on a lighting problem I am having.

 

Basically, the lights will flicker sporadically. When they do flicker it is each light on that particular dimmer. I am using wall mounted ETC Smartpacks and an ETC Express 48/96 run through an Empasis server. Some times they flicker as soon as they come on and some times they will be fine for a few hours before they start doing it. Also some times they may be fine for weeks before the problem arises.

 

I am fairly sure the problem is to do with the dimmers as I have saved a preset on the dimmer of each lamp on full and they still flicker so I'm pretty sure its not a DMX problem.

 

Also our electrician has been down a couple of times and run all sorts of tests and he is fairly sure it is not a power problem.

 

I have been in touch with ETC and they say it could possibly be the chips in the dimmers need replacing. Before I go ahead with this has anyone had similar problems with this equipment or is there anything else I could try to narrow the problem down.

 

The dimmers are around 5 or 6 years old and only maybe used once or twice a week so I don't think they should be failing so soon.

 

Any help would be greatly appreciated!!!

 

Many Thanks in advance..

[Mark M]

How many Smarpacks are you running and do they all do the same thing? Seems very odd that they all would have developed the same problem at the very same time?

[adam2]

If the flickering is only slight, though still iritating, then it could be a power qaulity problem (not a fault in your wireing)

An intermitant fault on the suppliers network, or the switching of a large load by another consumer can cause voltage fluctuations and result in flicker on incandescent lamps.

Try to find a 13 amp socket on the same phase of the same distribution board as the dimmer, and plug into this a low powered GLS lamp, via a d0m3stic dimmer turned up about half way.

Turn this lamp on when the dimmers are in use, if the dimmed theatre lanterns flicker, then observe if the GLS lamp also flickers ,if it does, then fluctuations in the incoming supply are likely.

If the GLS lamp lights normaly when the theatre lanterns are flickering, then the fault must be in the dimmers or the control thereto, or possibly the supply cable to the dimmer (though that should be unlikely if the installation has been recently checked by an experienced electrician)

[thetechguru]

Hi

 

I have seen similar problems before in older analogue racks and the fault has been traced to a High Impedance Neutral in the bus bar chamber. An Impedance as low as o.5 ohm in a heavy neutral connection is enough, under certain conditions, to cause flickering in the entire rig!

 

Problems have been solved by disconnecting the main Neutral in the chamber and cleaning then reconnecting. This fault would be most prevalent in badly balanced loads at around 35%( nasty point in the phase angles). Could be worth a shot by your spark.

[royallark]

Hi,

 

Thanks for all your responses. I am running 5 Smartpacks. 4 of them have started to do this over the course of about the last three months.

 

When the lights flicker it is every light on that particular dimmer. When it happens its usually one a dimmer at a time that seems to flicker.

 

I have tried softpatching and hardpatching with no luck.

[Ynot]

We have a number of Smartpacks in our theatre - in fact we had the very first rack-packs off the production line, with eser number 00001 to prove it. ;)

They are a very reliable rack and we've had few problems with them over the past 6 years or so.

 

However, we also have a couple of channels that flicker when at around 40 to 60%. This is I understand a definite dimmer cube problem, and as such I have purchased some replacement modules (cubes) to resolve the issue, though I've yet to replace them. They're very easy to do, though I would recommend that an exoerienced theatre sparks does the work. The 12-way racks have 3 modules, carrying 4 channels each, and are essentially a plug-in job. Take care, though, as it is possible to bend the contact pins when inserting.

 

Now, if your racks are of the same vintage as ours, which it sounds as though they may be, then it's worth checking the batch numbers on the modules (they look like big heat sinks). Call ETC with that info and you MAY find they're covered under the warranty as a faulty batch. I was told that regardless of age, they'd replace ours FoC as and when they went faulty, and true to their word we did have 2 swapped out a while back.

 

EDIT to add - just found the e-mail from 2004.

The power cubes with datecodes 0305 and 0306 are covered forever; the others have the standard 2-year warranty.

[royallark]

Massive thanks for that Ynot, thats really helpful.

 

I'll get ont o ETC pronto!!!!

[royallark]

ETC say that the fault with the dimmer cubes never resulted in flickering and that the batch of dimmer cubes that were replaced were locking either on or off or in some extreme cases exploding.

 

They now suggest replacing the processor unit rather than the dimmer cube but say it is very unlikely that 5 processor units would fail like this in the space of a couple of months.