Automated Fixtures Moving Heads running off Dimmers???

AlexJoKeys

Member
Hi all -

I'm currently a music/sound student and know about the audio side than lighting however I have a temporary job which requires that I use a DMX lighting system... - the basics of this is fine - theirs a strand 200 lighting desk which is simple as moving faders for dimmer brightness...ect.. However, on the lighting rig, their are 8 moving heads (Mac 500s). I was asked to use them and spent an hour looking for a switch to turn them on.. I eventually noticed that they were plugged into the strand dimmer system.. THEN on the strand desk, their were 4 faders with red tape half way up the channels. I pushed these 4 up, and the moving heads powered up?

Theirs also a Jester Zero 88 desk... The moving heads are linked to the Jester desk via DMX (and daisy chained). So I can control the heads from there.

While making presets and lighting scenes on the strand I hit blackout - the heads of course lost power instantly. When they came back on 2 displayed TEMP and wouldn't fire up.. After letting them cool, they came on... They seem temperamental...

Is this rigged up incorrectly? I read the Mac500 manual and it says nothing about power down procedure or cooling time like a video projector?... Could using these lights in this setup damage them? - also they are 230 volts.. So if they are getting "dimmed" power, I'm guessing they are receiving a lower voltage/amperage? I'm scared that the setup could damage them...ect.
 
Also note that - if you reduce the strand faders connected to the heads, they start to malfunction/flicker on their LCDs before dropping power... - I noticed this when sliding the faders down to switch them off...
 
Well, what you did was a hard shutdown - removing power completely rather than the standard Lamp-Off command followed by a hard shutdown. The wait period is similar to stadium lighting. The lamps are metal halide and can take a while to come up to full brightness. Alternately, they will need to cool before they can restrike, lengthening the process in the event of an unexpected power loss. As for the error code -- probably just a message informing you that the lamps were too hot for a restrike. This is completely normal.

Now, they *could* have them powered through dedicated relay packs which are profiled to be full on above 50%. However, taking the flickering in to consideration when you move the fader, I don't think this is the case. Relay packs are all or nothing. Sounds like they are running them off of dimmers which is a horrible idea, even if the slider is kept at full.

I can't believe people don't realize this and honestly I'm beginning to think that they deserve to fry their power supplies as a harsh lesson...
 
Well, what you did was a hard shutdown - removing power completely rather than the standard Lamp-Off command followed by a hard shutdown. The wait period is similar to stadium lighting. The lamps are metal halide and can take a while to come up to full brightness. Alternately, they will need to cool before they can restrike, lengthening the process in the event of an unexpected power loss. As for the error code -- probably just a message informing you that the lamps were too hot for a restrike. This is completely normal.

Thanks for the reply... Yes they are definitely powered off of the dimmers... I'll have a look into programming a Lamp-Off command...

I have done a search on the manual and it doesn't mention cool down periods? Is their like an unwritten rule in the lighting world about these fixtures?

Do you have any advice for using these lights in this scenario apart from not using the blackout function on the dimmers..?
 
Thanks for the reply... Yes they are definitely powered off of the dimmers... I'll have a look into programming a Lamp-Off command...

I have done a search on the manual and it doesn't mention cool down periods? Is their like an unwritten rule in the lighting world about these fixtures?

Do you have any advice for using these lights in this scenario apart from not using the blackout function on the dimmers..?

The practice of allowing a cool-down has been a source of debate here along the same lines as when to douse.

I personally observe a cool-down with the fans running for at least ten minutes. Most would think that the fixture temp can't possibly rise while the lamp is off, but when you remove the forced-air cooling provided by the fans, the heat from the still-hot lamp can build and damage components [citation needed, but honestly it really can't hurt to lamp off and run the fans while you go about your other post-show responsibilities]. Of course, any good you do there might be cancelled out by the fact that they are running off dimmed power and minimizing that time might be of benefit...

As for advice, there isn't much you can do short of putting the fixtures on dedicated non-dims. At least not where preserving the fixture's life is concerned. You might be able to "park" the fixtures' channels so as to lock out blackout and power-off's by inadvertently moving the faders (see your console manual). As mentioned, that won't make the fixtures any happier when running, but it might give you a few less headaches when programming or running a show.
 
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You must put the fixtures on non-dimmed power. Powering them through dimmers is asking to blow out the power supply and/or ballast. You should be able to purchase non-dim relay or constant modules for your rack, even if the rack is an older Strand CD80 (I would advise constant, prevents someone from accidentally killing them at the board, means that only people with access to the dimmer room can power them on).

Once you have them on non dims, you will either power them on through the dimmer room or park the channels on at the console.

Lamp down before powering units off is definitely necessary. This comes from someone who has worked with fixtures that have had issues due to this. Cutting power to a light with the lamp on can cause undue heat stress on the components inside that are supposed to have a fan blowing over them constantly. If you kill the lamp by killing power to the light, you are not allowing the internals time to cool. This can cause a sharp temperature rise which can damage components, especially the finnicky ones like sensors. VL2500s, for instance, MUST be left running with the lamp off for 5-10 minutes or else you can cause irreparable damage to the color and/or gobo sensor PCBs. I would allow at least 5 minutes for the units to cool down before cutting power to them, but 10 would be much better and could definitely contribute to the longevity of your lights (especially considering their age).
 

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