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Hot Striking HMI Bulbs

HMI Hot Striking Arri Fresnel Fixtures Ballast Saftey

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#1 Sam Bignell

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Posted 11 March 2017 - 11:38 AM

Hello Guys,

 

I know this has been posted before but I never found a conclusion to it.

 

I've always learnt that you can't restrike/hot-strike HMI bulbs meaning to turn them off and straight back on without blowing the bulb full-stop.

 

Every shoot I've ever been on this has never been the case nor even close to a concern from the DP. They restrike the bulb just 30 seconds after it being shut off even when the bulb has been on for 10-15mins or so, it makes a nasty sound from the bulb trying to re-light but other than that it's fine everytime.

 

So if someone can clarify some questions for me?

  1. The term Hot-Strike literally means from striking the bulb when it's HOT HOT, like full temperature hot, then it will blow or not restrike?
  2. Does the ballast & bulb actually have a major impact on how safe it is to restrike in reality, not theory.
  3. If the top question is true, how long is it best to wait? The higher the wattage = the more heat so the longer the wait?

Cheers Guys, will appreciate this.


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#2 Phil Rhodes

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Posted 11 March 2017 - 12:08 PM

There's no problem with immediately hot-starting HMIs, at least up to the 6kW level where I've used them. It is slightly rough on the lamps and will reportedly shorten their life somewhat, so don't do it just for fun, but in the grand scheme of things I've never seen evidence that it's a very big deal.

 

Even the best ballasts will sometimes fail to hot-start a lamp, particularly if you literally switch off then immediately back on again. Usually counting slowly to ten, then trying again, results in a successful start.

 

P


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#3 Sam Bignell

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Posted 11 March 2017 - 12:42 PM

Thanks for your response Phil, are you by any chance The Phil Rhodes.


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#4 Phil Rhodes

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Posted 11 March 2017 - 12:51 PM

Well, that's a first - nobody's ever asked me that before!

 

Er - which one were you thinking of? I'm not sure what sort of response is best!

 

P


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#5 Sam Bignell

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Posted 11 March 2017 - 12:54 PM

Haha, well probably not then I just happen to know a guy in the same area as you with an identical first and second name  ^_^ urhmm.


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#6 Jack OGara

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Posted 11 March 2017 - 04:02 PM

Some bulbs don't like it. I had a Philips bulb blow once because we had the generator low on fuel.

OSRAM has been fine though. 

 

They do specify if they can be on the packaging box for the bulb.


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#7 Phil Rhodes

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Posted 11 March 2017 - 04:34 PM

I had a Philips bulb blow once because we had the generator low on fuel.

 

How do you know the generator fuel situation caused it?

 

Can't see how. Did the generator actually run out of fuel? Even then, any but the most basic ballasts (and generators, for that matter) should deal happily.

 

Bulbs do occasionally explode, and it's not necessarily specifically because of whatever was going on at the time.

 

P


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#8 Adrian Sierkowski

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Posted 11 March 2017 - 05:38 PM

HMIs are often like lovers, sometimes you just don't know what's wrong and they explode on you..


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#9 JD Hartman

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Posted 11 March 2017 - 06:09 PM

Some bulbs don't like it. I had a Philips bulb blow once because we had the generator low on fuel.

OSRAM has been fine though. 

 

They do specify if they can be on the packaging box for the bulb.

What make, model and size generator was the HMI on?  Tow plant or putt-putt?


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#10 Jack OGara

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Posted 12 March 2017 - 02:59 AM

The generator was pretty much out of fuel and started to drop bellow the volts required by the ballast. So the ballast kept turning on and off. 

As in it hot striked the lamp a couple times.


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