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In Search of Some Ballasts


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#1 Tim Tyler

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Posted 30 December 2005 - 01:54 PM

I scored a couple of old LTM HMI sun guns on eBay for $10 (seriously) but I'm having some difficulty finding ballasts. The globe details are at http://www.osram.com.../hti250WSEe.pdf

I have a feeling the ballasts might be easier to locate in Europe. I'd be grateful if anyone had any leads.

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#2 Stuart Brereton

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Posted 30 December 2005 - 02:12 PM

Tim,

you've probably already tracked them down, but LTMs' US address is:

LTM Van Nuys

7755 Haskell Avenue, Van Nuys, CA 91406

Phone 1 (800) 762-4291

Phone (818) 780-9828

Maybe they can help. If not, is there any reason why an Arri or Strand ballast won't work?
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#3 Tim Tyler

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Posted 30 December 2005 - 02:25 PM

Yes, thanks. I talked to Stuart Guerrero at LTM last week and he's got nothing at his shop or in his circle of clients. We've got a call into the France office though, but they're out till next week.

I don't know if you can mix-n-match ballasts.
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#4 Phil Rhodes

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Posted 30 December 2005 - 04:45 PM

Hi,

Unless it's the same lamp type (and probably in the same housing) there is no guarantee of commonality between HMI ballasts. Different lamp designs require different starting and current regulation.

That said, you could always try building one. I would. But I'm nuts.

Phil
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#5 Rolfe Klement

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Posted 30 December 2005 - 04:51 PM

I think I saw a load of LTM gear lying around at Cinebuild in the UK : Call Tony Neale on
+44 (0) 20 7582 8750 or cinebuild@btclick.com

Not sure if they still have it

thanks

Rolfe
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#6 Tim Tyler

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Posted 03 January 2006 - 01:35 PM

No reply from Cinebuild yet.

A salesperson at Bron Kobold called the 270's 'extinct' :(

LTM Paris open up again on the 6th. I think they might be my last hope, unless...

Anybody know how to make an HMI ballast?
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#7 Hal Smith

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Posted 04 January 2006 - 03:48 AM

I researched obtaining a ballast for a fixture modification a couple of months ago. GE Lighting was able to help me some but when got deeper into the process I found out that its real hard, if not impossible, to get any engineering level information on ballast coils themselves. Ballasts seem to be exclusively constructed on an OEM basis for fixture manufacturers. A lamp manufacturer knows what's required to strike and regulate their products, but it's the engineers at the fixture manufacturers who design and/or specify the ballasts.

I am the original DIY guy, I've cobbled up all sorts of work-arounds but I hit a blank wall when I tried to improvise a ballast for my project. I did learn one thing from GE: hot restrike lamps do not have to be operated on a hot restrike ballast, they will work correctly off a properly designed ballast, in fact they last longer if NOT hot restruck.

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#8 Phil Rhodes

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Posted 04 January 2006 - 09:49 AM

Hi,

As long as you can find out what the lamp current is supposed to be when it's running, it should be possible to build a ballast. You might end up hand winding some inductors and doing head-bending mathematics in the design phase, and it would be most ideal to know what the strike range is (at least so you can find out if this is the reason it isn't starting properly).

Probably the easiest way to do it would be to use one of the standard switched-mode power supply controller ICs and an array of large MOSFETs, but you would almost certainly be winding custom inductors and it can be quite difficult to design these things to be highly efficient (although flicker-free is easy).

I should imagine it would be quite easy to drive them badly without knowing it.

Phil
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#9 Rolfe Klement

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Posted 04 January 2006 - 01:28 PM

Tim - I sent you a mail. Cinebuild have them - but for obvious reasons they are not keen to seperate out units - so they would want you to get the inverter ballast, mains power and lamp head, batteries, cables

Call Tony - UK lunch times

Or if it doesn't work out or is too much then I am sure you can build one

thanks

Rolfe
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