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2k Blonde - softstart/dimmer required?


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#1 Marc Roessler

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Posted 17 August 2012 - 02:12 PM

Hi,

is it a requirement to use some fort of soft-start or dimmer for a 2k Blonde (230 Volts version)?

I never had any problems with any 2k wattage lights so far, but this blonde I just bought seems to give me trouble. Just installed a brand new Osram FEX bulb in it (without toughing the glass envelope of couse) and the bulb blew within 2 minutes: it seems upon startup, one of the ends of the filament burnt loose (with a small blue flash). The loose end of the filament managed to fall right on the metal connector inside the bulb, so it continued to burn until I switched it off after 2 minutes - this is when I saw the problem. The lamp was in upright position and there was no vibration (light stand was used).

Are the FEX 2k bulbs for the Blonde more finicky? Or did I just happen to get a lemon as a bulb? Do they need a dimmer/soft start? The filament does look a bit more sturdy (though less well supported mechanically) than the 2kW's commonly used in fresnels, so does this maybe cause it to have a higher inrush current when switched on?

Greetings,
Marc

Edited by Marc Roessler, 17 August 2012 - 02:13 PM.

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#2 Stuart Brereton

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Posted 17 August 2012 - 02:43 PM

I've never heard of any need for a softstart or dimmer for these lamps, or for any tungsten lamp below a 20k. Perhaps you just got a bad bulb.
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#3 Brian Drysdale

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Posted 17 August 2012 - 04:08 PM

Never had a problem with a 2K blonde, sounds like a dud bulb. Redheads tend to blow more easily.
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#4 Marc Roessler

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Posted 17 August 2012 - 04:47 PM

Thanks guys. Tried another bulb (luckily I ordered two of them), this one worked.
When switching on still tends to blow the 16A fuse one the other time due to the inrush current, otherwise works like a charm.

Seems it was a bad bulb.
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#5 Lucas Griego

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Posted 17 August 2012 - 08:55 PM

Glad it was something as simple as a dud bulb. To echo what had already been said... there is no need for a dimmer to start up 2K's and the 2K's rarely seem to have much problem with blowing compared to something like a redhead.
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#6 Matthew Parnell

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Posted 18 August 2012 - 01:47 AM

Blondies and redheads blowing an excessive number of globes tends to be a pretty convincing symptom of problems with the lampholder.

While they are pretty robust heads overall, and tend to last in service for years with little more than a dust off and a little dry lubrication of the flood-spot worm gear and runners. Over time the lampholders tend to be affected by heat, handling in transit, the incorrect installation of the globe and the continual changing of globes amongst over things.

I would be giving the lampholders a quick inspection everytime you change the globe. Check for corrosion on the conducting nipple, check for discoloration and cracks in the ceramic. When you install the globe make sure it is neither too tight or too loose in the head.
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#7 Marc Roessler

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Posted 18 August 2012 - 04:33 AM

Blondies and redheads blowing an excessive number of globes tends to be a pretty convincing symptom of problems with the lampholder.


Had checked that before installing lamp, all looked good.
Good tip though, will check them once in a while.
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