Film-Tech Forum ARCHIVE: Bulb or Lamphouse Problem????

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Posted by Don Anderson (Member # 397) on 08-07-2006, 09:25 PM:

We have been having a problem with bulbs burning out way before their time. Here's what we have in the booth.

Christie Rectifier/Power Supply
Orcon 2500S Lamphouse

We have used Osram 1600W/HS and Christie bulbs with what seem to be the same problem. We used to get 2000+ hours on a bulb. We originally thought the Rectifier/Power Supply was the problem (originally a ORC powersupply). So did our Service Tech, so he installed the Christie unit in place of the old ORC power supply. Have no fear, we had a bulb begin to fail over the weekend. We have been keeping an hourly chart of the amps and voltage at each showtime (beginning and during run). I started up a movie on Friday night and the Lamphouse readings we around 13v and nearly 80 amps, with barely any light on the screen.The showtime before it the readings were 66amp and 22.6 volts. So I installed a new bulb and had readings of 68amp and 20.6 volts at the time of igniting, with basically the same readings all night and throughout the weekend.

Exhaust fans are working properly, bulbs are installed properly and anoide connectors secured to the lamps tightly. WE are baffled and so is the Service guy. We even had WI Electric aka WE Energies come out and install some gadget in the 3 phase box to measure spikes, etc. Nothing wrong there, watched it for over 4 weeks. Any ideas?????

At 425.00 a bulb, its getting expensive, and we are stumped. I've have worked here 8 years and never had this happen before. When the Lamphouse is running, the amperage and voltage is fine, and has continued to stay that way, up until about 400-500 bulb hours.

I had thought it was defective bulbs, but, defective from two different manufacturers???? I'm stumped. The bulb that was recently pulled over the weekend was not blackened or smokey looking at all, it looked fine. But, when we tried installing it in another auditoriums lamphouse it died instantly and turned milky white/gray inside, with a small piece of glass loose inside the bulb.

Posted by Louis Bornwasser (Member # 3063) on 08-07-2006, 10:10 PM:

The bulb you referenced in the last paragraph has been damaged in a way that caused it to fail internally. When the electrodes are made to flex (rough handling) they flex and destroy the seal internally; that is why you saw the small piece of quartz.

$425 is a bit high for a 1600. About right for a 2k (with a better warranty)

If you are starting a 1600 watt bulb, typically you start at 75-80% of the max output. Your settings are a little high for a new start. You have no where to go when the bulb gets older.

Hope this helps. Louis

Posted by Gordon McLeod (Member # 33) on 08-07-2006, 10:10 PM:

Where did you measure the voltage
I would measure it on the output terminals of the rectifier if it is still 13volts then I would suspect a short to ground in the lamphouse otherwise the rectifier
Does it flicker?
A lamp turning milky white is a seal failure usually

Posted by Don Anderson (Member # 397) on 08-07-2006, 10:25 PM:

Gordon, I took the readings of the lamphouse amp meter, and tested the voltage the same way. There wasn't any bulb flickering that I noticed.

Louis- There's nothing for me to set or lower on the Lamphouse or Power Supply. The only control on the Christie Power Supply is a knob with the numbers 1-4, it is located on the #1 setting (lowest). I'd prefer not to have to open the power supply and tinker around, I'd end up dead! Electrical work scares me!

Posted by Louis Bornwasser (Member # 3063) on 08-08-2006, 12:26 PM:

Inside the rectifier are links corresponding to line voltage. You are probably on the low setting. Moving to 230 volt or some other---higher--voltage will mean that #1 will be much lower in current. You could then settle on 2 or 3. Louis

Posted by Mark Gulbrandsen (Member # 72) on 08-08-2006, 03:27 PM:

Hard to believe that old 2500 that I installed is still there. Actually the ORC rectifier is probably ok too. They are not bad rectifiers actually they were made by LP Associates and are pretty much bullett proof except for an occasional bad diode.

Sounds to me like...
#1 You are paying too much for lamps.
#2 Your starting current is too high.
#3 You need a more knowledgable service tech thats better equipped tool wise, he should have tools to measure both inrush current and ripple to determine if your old rectifier was even at fault and before he put you through the expense of the Christie rectifier... Good techs that are well equipped are not always easy to find.

Mark

Posted by Don Anderson (Member # 397) on 08-08-2006, 07:12 PM:

Mark- the old ORC was in pretty bad shape, at least the case was falling apart!

You are right about finding techs, as far as I know, there are none in Wisconsin. At least every theatre owner that I've talked to gets techs from IL or MN.

I'm not afraid of getting my hands dirty, as I have been fixing Noritsu and Agfa minilabs for over 15 years at my day job. Unfortunately, thats film processing equipment, not motion picture equipment. I which I had someone in the area that would show me the ropes, as I would rather do techwork. [beer]

Posted by Mark Gulbrandsen (Member # 72) on 08-08-2006, 08:03 PM:

Well, putting the case back together is alot cheaper than installing possibly another questionable rectifier. I would get ahold of a DC clamp on amprobe and be darn sure your Amp meter is reading correctly before you do anything else. To me it sounds like either defective lamps or a very high operating current. What brand of lamps are these?

BTW: That lamphouse nd rectifier were out of the old AMC in Naperville, IL. It was already 15 years old when it went into the West Bend Theater.... And I installed it there in the mid 80's!

Humm, I would rather learn those minilabs... I always enjoyed darkroom work.. I just don't want to live in Wisconsin.

Mark

Posted by Don Anderson (Member # 397) on 08-08-2006, 10:29 PM:

Mark- The old ORC rectifier was removed from service back in May/June, its still laying around the booth, but not in service. The Christie rectifier was installed at that time.

We use either OSRAM XBO-1600W/HS or CHRISTIE CXL-16S bulbs, and yes, the price is about 425.00 a piece.

Many of you have mentioned that we are paying too much for bulbs. But, the price for these units seems to be the same at every dealer that I have called. If you are getting them cheaper and they are the same brand/model, inform me where to buy them [Smile]

We only order 1 backup bulb at a time, and keep a used spare or two on the shelves. We are a 3 screener.

Posted by Frank Dubrois (Member # 3042) on 08-08-2006, 11:24 PM:

Dont get Mark started on that. He will tell you that you CAN get them cheaper, but wont tell you where. [puke]

Posted by Scott Balko (Member # 438) on 08-09-2006, 09:44 AM:

I'm definitely no expert, and I hope this doesn't sound stupid, but I was picking up a film at another theatre that the manager said they were having similar problems with an ORC. They said that the cover was on backwards and all the cooling air was going out the vent. Seems that the cover could be put on with the vent toward the front or the back but should have been put on toward the front so the cooling air is drawn through the bulb chamber. With it on toward the back, all the cooling air was drawn out without going over the bulb. I don't know if this applies to your model lamphouse, but I thought that might be an easily overlooked thing if it does matter. Hope you figure it out. Good luck. [Smile]

Posted by Don Anderson (Member # 397) on 08-09-2006, 10:02 PM:

Scott- You are right about some of the ORC lamphouse units. Two out of three of our ORC's have the exhaust port located at the rear of the units. The other ORC(2500c) has it located on the front. The lamphouse that were are having problems with is a 2500S, not the C version as stated earlier on in this post. I need reading glasses to see the damn small tags on the backpanel. Both the C and S actually have an extra exhaust hood that sits on top of the lamphouse cover. I can see how it could be reversed. Unit in question, has the exhaust port at the rear of the lamphouse, as shown in the operators manual. So, I guess we have it set up properly. Plus, this problem that we have been having only started this May/June, and the lamphouse has been in place for 25 years or so. Nothing has changed or altered.

Although we have 3 ORC lamphouses in our booths, each unit is a different model, and each power supply is a different type too!

3 phase in lower booths, and a newly installed 3 phase in our upstairs booth. Why did we put 3 phase upstairs?? We couldn't locate a single phase rectifier/power supply in the WI/IL area, and ending up buying one from IL. It would have cost too much to ship one it from anywhere else.

As for the old ORC power supply that Mark installed in our upstairs booth, it had seen better days. Yes, maybe it didn't have anything wrong with it, but it was unsafe, the cover was shot. It would constantly pop the breaker on the side of the case. Plus, the Electrian that wired the booth made a comment about it!

Posted by Mark Gulbrandsen (Member # 72) on 08-09-2006, 11:33 PM:

FYI: The Strong 1-3K switcher runs on single or three phase power. It probably would have cost less than what your electrician probably charged you to install three phase in that upstairs booth. I installed the downstairs booths not the upstairs.

Frank,
Haven't you figured the diode thing out yet? Its no more difficult than selecting motor oil for your car from a chart.

Mark

Posted by Frank Dubrois (Member # 3042) on 08-09-2006, 11:57 PM:

Mark,

To ME, it is not that easy. I emailed you with another question about the selection of diodes and you never responded, so I am still stuck. Perhaps it will just come to me one day and I'll go back to that site and order the hell out of the diodes...but until I get struck with that information OR someone is patient and answers questions, I'll continue to have my company pay $30 a piece. Thanks for the help! [thumbsup]

Posted by Gordon McLeod (Member # 33) on 08-10-2006, 12:24 AM:

Most of the older ORC lamphouses the exhaust must be located towards the back

Posted by Michael Schaffer (Member # 1204) on 08-10-2006, 12:29 AM:

I don't know if this has been mentioned before, but in addition to the things discussed above, a look should also be taken at the reflector. Sometimes when the reflector gets old and the reflective coating hazy or even starts to come off in tiny flakes, the light output is bad and since the dichroic properties of the coating are lost, it gets much hotter inside the lamphouse than is good for the lamp.

Posted by Don Anderson (Member # 397) on 08-10-2006, 01:15 AM:

Gordon- The lamphouse that were are having problems is vented from the back of the unit.

Mike- I installed a brand new reflector in the 2500S about 1 1/2 years ago. So, that's not the problem. But, I could use a new reflector in one of the lamphouses in the main floor both!

Mark- The electrican is a friend of mine, he actually did it fairly cheap. He also wired up our outlets for our digital screen advertising setup which was more of a pain than the 3 phase. he ran a line up from the lower level booth, under the balcony seating and into the booth. Did it in about 2 hours. I had to explain to him what needed to happen when the digital was powered up, and what it was to do upon the automation kicking in. Works like a charm!

Posted by Mark Gulbrandsen (Member # 72) on 08-10-2006, 09:14 AM:

quote:
To ME, it is not that easy. I emailed you with another question about the selection of diodes and you never responded, so I am still stuck. Perhaps it will just come to me one day and I'll go back to that site and order the hell out of the diodes...but until I get struck with that information OR someone is patient and answers questions, I'll continue to have my company pay $30 a piece. Thanks for the help!

| IP: Logged

Sorry Frank but out of respect to other dealers here that also sell them I can't post that info. I'd be happy to explain in great detail to you the space shuttle main engines start sequence if that would be of any help...... [Cool]

.

"The HPOT consists of two single-stage centrifugal pumps (a main pump and a preburner pump) mounted on a common shaft and driven by a two-stage, hot-gas turbine. The main pump boosts the liquid oxygen's pressure from 422 psia to 4,300 psia while operating at approximately 28,120 rpm. The HPOT discharge flow splits into several paths, one of which is routed to drive the LPOT turbine. Another path is routed to and through the main oxidizer valve and enters into the main combustion chamber. Another small flow path is tapped off and sent to the oxidizer heat exchanger. The liquid oxygen flows through an anti-flood valve that prevents it from entering the heat exchanger until sufficient heat is present to convert the liquid oxygen to gas. The heat exchanger utilizes the heat contained in the discharge gases from the HPOT turbine to convert the liquid oxygen to gas. The gas is sent to a manifold and is then routed to the external tank to pressurize the liquid oxygen tank. Another path enters the HPOT second-stage preburner pump to boost the liquid oxygen's pressure from 4,300 psia to 7,420 psia. It passes through the oxidizer preburner oxidizer valve into the oxidizer preburner and through the fuel preburner oxidizer valve into the fuel preburner. The HPOT is approximately 24 by 36 inches. It is attached by flanges to the hot-gas manifold."

As for the diodes I guess you could purchase them from
another dealer that stocks them and then you'd have the type number... there.... that wasn't too hard to figure out was it...

Mark

Posted by Dave Barker (Member # 3864) on 08-10-2006, 01:03 PM:

From an electricians point of view, current(amps) and Voltage(volts) are inversely proportional. When you limit the voltage it will raise the current until the demand is satisified or until the limit of current is reached. If normal operating voltage on an arc lamp is 24 volts and normal operating current is 65 amps you can take the volts and multiply that times the amps and get 1560 watts. Reasonable for a 1600 watt lamp, should light and burn bright.
Now limit the voltage using some type of flaw or failure in the supply leads, rectifier, incoming voltage, whatever the case might be, even if you deteriorate a connection between the lamp and the supply output. The leads may not be very long and just measureing with an ohm meter wont discover a resistance that could cause limiting under a high current condition. Also if any of the connectors or the leads were sized too small in a replacement procedure it could be causing more resistance to bring that voltage down as well. So you say we have reduced the voltage down to 12 volts now? Not exactly 12 volts but for the sake of explanation and easy math. What just happened to the current (amps) demand? You are asking a power supply that is rated at perhaps 80 amps to give you DOUBLE what you had before. 12 volts x 130 amps is guess what...1560 watts....... The power supply can not take the required load so your output is reduced in your lumens that actually reach the screen.
Now the reason for the lamp failure could be the high current that is causing deeper than normal pitting and also heating up the lead ends that would cause even higher resistance and more heat. This in turn could cause minute fractures of the glass envelope that would let air in causing a "milky cloud" coating on the inside of the lamp. (This is where you get dangerously close to exploding a zenon lamp inside a housing that will shatter a glass reflector.) So it acts like an airflow problem but actually is supply.
So why are they failing so soon and new lamps dont experience the same problem if it is a supply flaw? The only thing on a lamp that changes over its life under even perfect conditions is the electrodes. Pointy end (laymens term) gets pitted and shortened and the bulky end gets all kinds of speckles of material that came from the pointy end's pits. This changes the distance between and the surface structure of the two arc surfaces which changes the pattern in the arc as well as the wattage.
Why does the wattage go up instead of down when light is less? If the 'trodes are closer together from the raised surfaces, the resistance is lower and the arc pattern will be narrower in shape. Less arc, less light. If you've ever done any arc welding this will be easy to comprehend.
So you want an answer not a math and electrical survey of what you already know is not working? Double check EVERY connection, follow EVERY wire, look for excess heat at connections, remove connections one at a time and inspect and clean them carefully, scrape them to bare metal if there is any discoloration, factory crimps are ok but if you have any field crimps check them they should be rock solid with no movement in the wire. Also double check that the proper diodes for your rectifier are being used. If you got those used, you may have something that was someone elses nightmare that was modified outside of factory specifications.
What might have changed to start this problem now and wasnt doing it before? Could be an indication of a problem in the AC supply leading to your supplies that only shows under load. Have current checks done on all 3 legs of the 3 phase to make sure they are even. Your electrician can do this with an Amprobe. Do it over a period of time during operation measured at the rectifier where the power comes in so no other equipment is measured. If you have an imbalance that can cause abnormal voltages on the lamp supply as well.
Seems to me your startup voltage is ok at 20 to 22 volts but it should gradually run up to 25 volts after 5 minutes. It might be that you do need to "pump up the transformer" jumper bars on the AC side for the correct voltage supply. 3 phase is 3 phase but there are different variations on voltages. The variations of 208, 220, 230, and 250 volts are enough to cause a lower voltage at the DC side.
You might get less damage to your lamps at startup if you had a higher voltage that could start arc quicker than if you use a lower setting for your 1600 watt lamps.
Well I am drained, good luck. Just remember, all the obvious things that may be overlooked. You might be looking for a haystack and not the needle.

Dave

Posted by Frank Dubrois (Member # 3042) on 08-10-2006, 01:23 PM:

quote: Mark Gulbrandsen
"The HPOT consists of two single-stage centrifugal pumps (a main pump and a preburner pump) mounted on a common shaft and driven by a two-stage, hot-gas turbine. The main pump boosts the liquid oxygen's pressure from 422 psia to 4,300 psia while operating at approximately 28,120 rpm. The HPOT discharge flow splits into several paths, one of which is routed to drive the LPOT turbine. Another path is routed to and through the main oxidizer valve and enters into the main combustion chamber. Another small flow path is tapped off and sent to the oxidizer heat exchanger. The liquid oxygen flows through an anti-flood valve that prevents it from entering the heat exchanger until sufficient heat is present to convert the liquid oxygen to gas. The heat exchanger utilizes the heat contained in the discharge gases from the HPOT turbine to convert the liquid oxygen to gas. The gas is sent to a manifold and is then routed to the external tank to pressurize the liquid oxygen tank. Another path enters the HPOT second-stage preburner pump to boost the liquid oxygen's pressure from 4,300 psia to 7,420 psia. It passes through the oxidizer preburner oxidizer valve into the oxidizer preburner and through the fuel preburner oxidizer valve into the fuel preburner. The HPOT is approximately 24 by 36 inches. It is attached by flanges to the hot-gas manifold."

See, and I thought it was just a matter of counting down from 10 to 1. I don't spose you'd let me know where I can find a oxidizer preburner oxidizer valve?

Posted by Mark Gulbrandsen (Member # 72) on 08-10-2006, 02:26 PM:

Sure,

Just contact Rocketdyne... be sure to have the serial number of your engine handy so you get the correct version of the valve... [thumbsup]

Mark

Posted by Eric Robinson (Member # 2966) on 08-10-2006, 05:07 PM:

As a sidenote, if one were to measure the dc voltage from the positive output terminal to the positive connection at the bulb, while the bulb is lit, ideally you would measure zero volts becuase the conductor from the supply to the bulb would have close to zero ohms resistance (in a perfect world.) Therefor, since the conductor is of good quality with very low resistance, it will not drop any voltage. The same goes for the negative conductor from the supply to the bulb connection. There may of course be some obstacles in the path such as a shunt or ignitor which may show that a small voltage is present though.

Although you mentioned that you have several different versions of equipment, you could compare voltage measurements as I described above between two similar lamphouses running at roughly the same output. This can be tricky though because firstly it would require you to place a measurement lead at a bulb connection and the lead wire must not be too close to any other metal during the ignition phase. Also the dvm leads can not be connected to the DVM during ignition due to the high voltage discharges during ignition which would likely kill your DVM.

In conclusion, this is probably a horrible idea to try, but it would illuminate any possible unsuspected voltage drops in your DC electrical path.

Posted by Mark Gulbrandsen (Member # 72) on 08-10-2006, 05:40 PM:

quote: Eric Robinson
As a sidenote, if one were to measure the dc voltage from the positive output terminal to the positive connection at the bulb, while the bulb is lit, ideally you would measure zero volts becuase the conductor from the supply to the bulb would have close to zero ohms resistance (in a perfect world.) Therefor, since the conductor is of good quality with very low resistance, it will not drop any voltage. The same goes for the negative conductor from the supply to the bulb connection. There may of course be some obstacles in the path such as a shunt or ignitor which may show that a small voltage is present though.

Actually there exists cyrogenically cooled cable that comes pretty close to that perfect wire theory. Its used in particle accelerators and physics expereiments that are done on huge scales....

Mark