Film-Tech Forum ARCHIVE: Xenon Bulb Question

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Posted by Mitchell Dvoskin (Member # 751) on 04-09-2001, 11:07 PM:

I have a Kneisley L-100-3 lamphouse with an Osram 500 Watt bulb, installed in November of 1994, and if the meter is to be believed, has 813 hours on it. The bulb was rotated once for a 1/2 turn, about 400 hours ago.

Of late, but not all the time, it is taking multiple tries to get the bulb to light. Once it does, it performs fine, with no flicker or instability.

I was wondering if rotating the bulb again would help the situation, and if so, should it be a 1/2 turn, or a 1/4 turn?

I was also wondering if boosting the power up one notch (slightly over recommended rating) would help, or would I be risking the bulb exploding?

Any suggestions would be appriciated.

/Mitchell

Posted by John Walsh (Member # 168) on 04-09-2001, 11:34 PM:

Osram only makes one 500 watt bulb; the XBO 500 W/H OFR. It is rated for 2000 hours.

The igniter (part of the power supply) may have a problem. I do not think rotating the bulb will help, and may make it a little worse (more flicker.) I would try changing the bulb first before doing anything complicated. Is the bulb dark-colored?

What is the definition of "one notch?" The max suggested current is 28 amps, max voltage is 17 v. That comes out to 476 watts, so if you mean turn it up to 500 watts, that would probably be OK, but no farther.

Posted by Josh Jones (Member # 447) on 04-09-2001, 11:51 PM:

Hey, I have this same lamphouse

mine is burning at 20 amperes and doesn't appear to flicker. what power supply are you using? and I hear Kniesley isn't making the bulb assemblies for these anymore. how did you deal with that?

I also need a manual for this beast. mine doesnot like to strike when the bulb is hot.

Josh

Posted by Darryl Spicer (Member # 711) on 04-10-2001, 12:12 AM:

The old theater i used to work for used kniesley 2000 watt lamphouses. We had problems trying to strike the bulb when it was hot also. What we had to do was replace the igniter with one that was ment to be for a strong lamphouse. It worked very well and did not have anymore problems striking bulb when hot.

The tech at the time told me that the design of the lamphouse had the existing ignighter positioned to close to the reflector mounting brackets and energy was arcing over to the brackets causing a strike problem when hot.

Do not know if that is the same problem you are having but that is what they did to fix our problem at the time.

Posted by Josh Jones (Member # 447) on 04-10-2001, 12:42 AM:

well, I suppose you could put some teflon or corona dope over that bolt to prevent arc over.

Josh

Posted by Mitchell Dvoskin (Member # 751) on 04-10-2001, 09:13 AM:

When I get home from work tonight, I will open up the lamphouse and check out the bulbs condition. I'm expecting it to be fine. I am currently running at about 25 amps, using the Kneisley power supply that came with the lamp house, model R-2180-4.

As far a changing the bulb, I have a new ORC 500 bulb. Are they any good? Are they safe? I have previously always used OSRAM.

Josh - As far as I know, Kneisley has disowned these units. I called them about 6 years ago looking for a manual, and was told that they do not have any manuals (not even photo copies), parts, etc. for them. What "bulb assembly" are you refering to. I know they no longer make the reflector, but mine is in good condition and should last for many years to come.

Posted by Josh Jones (Member # 447) on 04-10-2001, 10:45 AM:

When it came time to change the bulb in these suckers, the reflector and bulb came as one piece. now that they dont make the reflectors anymore, you have to get the bulb out of the reflector assembly and put a new bulb in.

Josh

Posted by Mitchell Dvoskin (Member # 751) on 04-10-2001, 01:11 PM:

Josh,

Kneisley may have sold the assembly with the bulb pre-installed, but they are definately not one peice. I last changed my bulb back in 1994, so I don't remember the details, but the bulb is mounted into and locked down in the back of the reflector assembly, but it is not part of it. At the time I changed the bulb, I did not realize how easy it was to remove the whole reflector assembly, so I changed the bulb by removing the front glass and taking the bulb in and out though the front, leaving the reflector in the housing.

If I remember correctly, there is an allen screw in that locks down the bulb in the assembly. I'll check tonight when I open the lamphouse and let you know.

Posted by Aaron Sisemore (Member # 145) on 04-10-2001, 02:10 PM:

>>I have a new ORC 500 bulb. Are they any good? Are they safe? I have previously always used OSRAM.<<

IMO, ORC (Now called PerkinElmer) bulbs SUCK HORRIBLY. They are a bitch to strike after only a few hours, and don't usually last very long in horizontal applications. Safe? I have had only ONE ORC bulb explode in operation, all the others just blacked out or the ceramic crumbled on the electrodes. I figure they are as safe as any other xenon, provided you take the precautions when handling one.

Stick with the Osram.

Aaron

Posted by Gordon McLeod (Member # 33) on 04-11-2001, 01:21 PM:

Both Norelco and Kniesly made a lamphouse that used a intigrated 500watt xenon reflector lamp. The lamp was made by Osram and GE. It was very quickly discontinued and for a while a seperate reflector was available. I doubt if it is now. You may want to look into the cermax® line of intigrated xenon lamps as a replacement