Film-Tech Forum ARCHIVE: Growth on Anode

This is topic Growth on Anode in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by William Phillips (Member # 1162) on 07-25-2006, 11:10 AM:

The lamp in the picture has been in service for just over 2000hrs. It is a Ushio 16SCBU. The light off the lamp is stunning and the arc is very stable. The only way i found the growth was when I removed it for cleaning the mirror. There were no signs on screen of anything funny going on.
Does anyone have any suggestions as to what it could be?.
I have spoken to Jack Roe (uk) who as always are very helpfull and we both came to the conclusion that its just one of those things. None of the other lamps that have run on this machine have had this. Lamphouse is Cinemeccanica CX21H, Irem AS16040A igniter, Irem N3/ 75DN rectifier with diodes and caps replaced 5 years ago.
The light is so good the lamp has gone back into service [Big Grin]

Posted by Tommie Evans (Member # 2674) on 07-25-2006, 11:47 AM:

I think it's just a characteristic of the electrons jumping out from the cathode and firing particles of tungsten thus hitting and collecting on the anode face, usually attributed to high AC ripple? I've never seen a perfect electrode after removing a used lamp (light output still amazing) but I have seen all kinds of growths and splits on the cathode tip and anode. The lamp in your picture still looks in good condition with no blackened/whitened quartz.

Posted by William Phillips (Member # 1162) on 07-25-2006, 12:01 PM:

Cheers Tommie
The quartz still looks like new, there is just the normal dust ring around the cathode shaft, but thats it. There is no blackening at all. We have had some very freaky power down here the last few weeks, the hot weather and thunderstorms, that might have something to do with it.
This is the 7th Ushio lamp ive used in this cinema, and they have all performed very well. One of the first 16SCBU versions I had got to 4000hrs, the only reason i replaced it was I didnt want to push my luck [Smile]

In another machine I use the 21SCBU, the light is not as bright as Osram but the stability of the arc and quality is far better. I find the Ushio give a cooler light on screen.
I am also thinking of getting the AFU units for the rectifiers, one screen uses a N3-100 and the other is the N3/75DN.I know Irem have a higher ripple than others but thats what Ive got, but I can minimise it as much as possiable.
I know lets put a few big caps on the DC line [Eek!]

Posted by Tommie Evans (Member # 2674) on 07-25-2006, 12:14 PM:

Hi William

I'm not familiar with the Uisho range, what size lamp is that? I have generally worked with Osram, Cinemeccanica CC7040H lamphouses and IREM console rectifiers.

Posted by John Pytlak (Member # 331) on 07-25-2006, 12:41 PM:

Those electrodes look very good for a lamp with 2000 hours on it. Just normal wear. Perhaps you've had more hot ignitions due to your power outages?

Posted by William Phillips (Member # 1162) on 07-25-2006, 12:52 PM:

The Osram lamp would be XBO1600WHSC (16SCBU) and XBO2000WSHSC (21SCBU). I use both Osram and Ushio, and will try pretty much any lamp once.
The weird power we had was not enough to drop the contactors in the rectifiers, the phase that they were on was annoyingly ok it was the other 2 that were all over the shop.
[Mad]

Both machines once struck generally don't get turned off. Normal weekdays strike at 4pm until 11-1130pm and on weekends and holidays, 11am till 11pm all days.
The console rectifiers unless they are switch mode are pretty much the same as the N3 series, its just the casing thats different.
The CX21H lamphouses that I run give an amazing light on screen and also very easy to work on [Smile]

Posted by Randy Stankey (Member # 64) on 07-25-2006, 01:17 PM:

Don't worry about it until your xenon lamps electrodes start looking like this:

A certian amount of deformation is normal in most xenon lamps.

Some causes of excessive deformation are AC ripple and too many unnecessary strikes of the lamp. I think over powering the lamp may contribute but, that, I'm not sure of. (Over powering is bad for a lot of reasons.)

Unless it starts getting noticibly worse, don't fret it. [Smile]

Posted by William Phillips (Member # 1162) on 07-25-2006, 01:20 PM:

Ok so mine seams to be in perfect condition then [Big Grin]

Posted by Monte L Fullmer (Member # 2797) on 07-25-2006, 01:42 PM:

Now..Ive caught information that Ushio bulbs are NOT designed for cinema work..mainly for spotlight/searchlight applications...even though Ushio is the parent company for Christie, but manufacture their own bulb line.

....You ought to see a LTI bulb with 2000 hrs on it (if one can last that long..LOL) - anode looks like a moon crater being such an inferior tungsten.

..You ought to see a Christie bulb with over 7000 hrs on it - you don't want to pull it since the light output still looks great - even if it does have the ripple "horns" on the anode..and has very little flicker..

-Monte

Posted by Tommie Evans (Member # 2674) on 07-25-2006, 04:53 PM:

William, there are more thunderstorms/hailstorms/flashfloods heading in from the west [Cool]

. Our cinema is one of the largest metal structures for a few miles and i've known it to be struck several times, nothing that has affected elecky or anything though [Eek!]

Posted by Charles Greenlee (Member # 3856) on 07-25-2006, 06:52 PM:

I have an Osram bulb with almost 10k hours of it, over a run of about 10 years. There is darkening of the evnvelop, but about the amout a bulb at half it's life would have, if that. Still produces good pictures. In fact, the only reason we pulled it was the guy that was taking our bulb inventory about Sh*t himself when I read off the hours and install date. He had me double check the serial, and then check it on the collar of the bulb itself to be sure. He said "Change it now!", he didn't even want me to wait till after the next show which was supposed to start in less than 5min. He was like, "it could explode at any time"

Posted by Randy Stankey (Member # 64) on 07-25-2006, 09:19 PM:

10,000 hours on a xenon lamp designed for 2,000-3,000 is pushing it. Your guy was right in demanding that it be changed but, since the thing had been left in that long, it probably wasn't worth it to delay a show and inconvenience paying customers just to change a lamp. It could have been done in between shows.

Why was the lamp left in that long in the first place?

Posted by Mark Gulbrandsen (Member # 72) on 07-26-2006, 12:17 AM:

It looks like high inrush current to me. Could also be the typically higher ripple of the Irem unit you have. Ushio lamps are the samae as Christie Lamps... Ushio is actually the parent company of Christie Digital.

The longest lived 2K I've seen was a christie lamp at just over 16k hours... about 7 years of service in this location. I've seen others go well over 12K and many to 10k. The envelopes are still for the most part clear.... they just become hard to ignite. And who says that spending just a few extra dollars for a better lamp doesn't pay off...... [Roll Eyes]

.

Mark

Posted by William Phillips (Member # 1162) on 07-26-2006, 03:59 AM:

Tommie wrote
"William, there are more thunderstorms/hailstorms/flashfloods heading in from the west . Our cinema is one of the largest metal structures for a few miles and i've known it to be struck several times, nothing that has affected elecky or anything though"

Cheers for that Tommie.
At the sign of any bad weather our electricity supply goes to [bs]

We are so far away from pylons, powerstation and a city its no wounder.
Last year we had a direct hit from lightning, it killed our complete fire alarm system, but cinemas kept running happy, now thats weird. We had a complete rebuild 3 years ago and have more steel work in this building than a steel works. Lucky there a huge amount of lightning bonds. Our fly tower and smoke vents act like a gigantic lightning rod [puke]

The longest I have ever run a lamp for was 6500 hrs. It was a vertical XBO1600watt Osram. Running in a Cinemeccanica CX1600 with a single phase T&R rectifier.

Mark, none of the other lamps that have been on this rectifier have ever had any growth like this one. I have been thinking of getting the AFU units for both rectifiers. During the rebuild, the substation on our land was upgraded for us. We now have a 3phase supply of 600amps per phase [Big Grin]

Since that was done, the power has been quite bad but not enough for the supply company to install a logger.

[ 07-26-2006, 09:38 AM: Message edited by: William Phillips ]

Posted by Charles Greenlee (Member # 3856) on 07-27-2006, 02:32 AM:

Randy. I'm not sure why. All I know is that we had a lamp go out in another house, we replaced it. When we called to notify Carmike "Technical" Dept. about it so they could order a replacment, they said they couldn't because they still showed we had 2 bulbs left in spare for that wattage. After trying to convice the guy that we were out, he had me go do the bulb inventory, consisting of what bulb (SN) (Model Number) (Wattage if not part of model number), on what screen, and hours run and install date. Well, we found the 2 spares, already in projectors, no one had called on previous occasions to let Tech Dept. know. And that is the call when the Guy on the phone crapped himself, when I read him the info on the 10yr old bulb. BTW, aside from the fact it still provided good illumination, it also usually ignited on first strike, maybe second on an off day. Osram sure enjoyed hearing about it. Their rep on the phone said she's had a few accidentally run that long, but it was rare. They wanted everything about it. Serial, model, hours, install/removal dates, lamphouse model, amps/volts, etc.