Film-Tech Forum ARCHIVE: Screwed up ORC xenons! (pics inside)

This is topic Screwed up ORC xenons! (pics inside) in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Dan Lyons (Member # 1454) on 12-05-2003, 07:56 PM:

Anyone care to guess what's wrong with this picture? hint: note the threaded end on the right, then look at the placement of the anode and cathode!!!

A glut of these 750w xenons has been up on Ebay over the past year. Who knows how many people running ORC M1000 lamphouses have bought one, only to have disastrous results!! [puke]

Anyone ever seen these before? What are they used for?

Danny

Posted by Bruk Mogos (Member # 2043) on 12-05-2003, 08:30 PM:

The images are to dark, can't really see it clearly to determine what's wrong with it, but from what I can see it look's like the fan in not blowing directly to the bulb like it suppose to. So there is to much heat to cause the malfunction.

Posted by Richard Fowler (Member # 893) on 12-05-2003, 09:08 PM:

This bulb is for a follow spot and search light with reversed anode and cathode location.....not for cinema lamphouses.

Posted by John Pytlak (Member # 331) on 12-05-2003, 09:16 PM:

Here's what the cinema lamphouse lamp should look like:

( from http://www.donsbulbs.com )

Posted by John Eickhof (Member # 323) on 12-06-2003, 12:11 AM:

Richard is correct, they are designed for the early Strong Super Trouper xenon conversion kit that went in the Super Trouper carbon arc lamphouse! They reversed the anode in order to prevent a sharp spot on the optical system of the spotlight. Modern Xenon Super Troupers still have the bulb reversed, but the mounting is designed to take the conventional bulb.

Posted by Dan Lyons (Member # 1454) on 12-06-2003, 02:38 AM:

Yep, you guys got it. It's reversed~! Thanks for the info about what it's used for.

Danny

Posted by Pete Lawrence (Member # 130) on 12-06-2003, 05:35 PM:

I was wondering what the reversed anode - cathode lamps were used in. Some one gave me several new Ushio UXL16MSVK lamps a couple years ago. I did catch the reversal before I tried to use them in anything. [Smile]

Thanks Dan for bring up the subject.

Posted by Scott Norwood (Member # 30) on 12-06-2003, 06:05 PM:

[cue annoying Abba song]

Hmm...the carbon arc version of the Super Trouper works just like a cinema lamphouse, with the positive carbon closest to the "front" end of the followspot. Why did they decide to reverse the orientation for the xenon version (which I haven't seen up close)?

Doesn't the xenon conversion kit use a vertical bulb?

Posted by Phil Hill (Member # 371) on 12-06-2003, 06:08 PM:

Hey Scott...how dare you? Get with it! There is NO annoying ABBA song! [beer]

>>> Phil

Posted by Richard Fowler (Member # 893) on 12-06-2003, 07:25 PM:

The main reason for the reversal on early Strong and the Ushio follow spots was to lessen a hot spot caused by the variable lens carriage at certain e.f. points and flicker problems when pointing the followspot in a downward angle.

Posted by Mark Gulbrandsen (Member # 72) on 12-06-2003, 08:26 PM:

Serveral of the Chicago downtown art theatres had down tilt so great that they had to utilize the lamphouse fror the Super Trooper(Lum-Ex actually) with the reverse lamp configuration just to keep the lamp lit!

Mark

Posted by Steve Kraus (Member # 476) on 12-06-2003, 10:05 PM:

I'm a little puzzled. If the lamp is reversed does the light mostly go forward and not utilize the reflector? Perhaps I'm thinking too much like carbon arc lamps where the light mostly comes from the positive crater as opposed to xenon where it's a ball of hot plasma.

Posted by Gordon McLeod (Member # 33) on 12-12-2003, 10:04 AM:

All the xenon followspots utilise the reverse mounted lamp
In live theatre and particularly broadcast even small amounts of flicker or wandering arc is a big issue and because most spotlight applications ahve a downward angle of about 45 degrees the normal lamp configuration would have the cathode far to high above the anode for stable let alone safe operation

Even in the reverse mode magnetic stabalization is still difficult to maintain a stable arc especially if the lamp is being apnned around quickly

Of all the xenon followspots the Xebex line is probably the best of the lot for stability the strongs almost always are very lamp fussy

The reverse mounting does reduce the efficiency of the system as the anode shadow vs the hole on the reflector is an issue

Posted by Ken McFall (Member # 845) on 12-13-2003, 07:26 AM:

If I rememeber correctly the early three electrode Thorn xenon lamps used in the BTH lamphouse were also reversed....

Posted by Gordon McLeod (Member # 33) on 12-13-2003, 02:52 PM:

Ken you just brought back a lot of bad memories 3 electrode xenons though in this case they were on GK lamps bang bang bang