Film-Tech Forum ARCHIVE: Cinemecannica Model 7040 7K

This is topic Cinemecannica Model 7040 7K - Losing Amps after start in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Bob Brown (Member # 1205) on 05-24-2003, 11:34 PM:

Need some advise as what could be causing the loss of amps after start.

EQUIPMENT: Cinemeccanica Model 7040 DATE CODE:0601
LAMP: OSRAM XBO 7K
RECTIFIER: IREM X3-G180

About 2 mins after lamp is lit, you can see a gradual drop in amps on the volt/amp meter. From a starting point of 150 amps, it will drop to around 145 and then you can see the amp meter bounce back and forth between 145 - 140 amps. We are also getting a real bad flicker on the screen, which I am sure is a result of the amp problem. We have checked all internal connections all are tight. I did notice major discoloration on the negative connection for the lamp. The steel connector has turned blue,(not sure if this is normal as I have nothing to refer to). I have checked and we are getting the proper amount of ventilation to the lamphouse. We have replaced three lamps in the last two months due to severe lamp flicker. This problem just started about two months ago. Before this problem, we were getting around 650 - 750 hours from the lamps, now we are changing them out with about 150 hours. Each time lamps are changed, we use a different serial number, so I do not think it is the lamps. So, I hope that someone may have some suggestions?
We have contacted Cinemeccanica, they suggested installing a voltage filter. My techs are not sure this will cure the problem.
Any Ideas?
Adam Martin....Got any Ideas? You know the equipment!!

Posted by Mark Gulbrandsen (Member # 72) on 05-25-2003, 12:33 AM:

You can check out all the normal things....especially all your heavy DC connections from start to finish. That amount of drop is not too unusual but the bouncing around at around 5 amps says to me that the arc is wandering around a bit...the lamp is not stable.

I'd be willing to bet that its the lamp. Buy a Ushio/Christie lamp next time, you'll have lots less troubles. If your dealer is selling you Osram lamps he is really doing you a dis-service.
Mark

Posted by Gordon McLeod (Member # 33) on 05-25-2003, 09:48 AM:

first the 7k lamp has about a 500 hr life span and tends to get very flacky after that point
Check the magnet in the lamphouse it may have been bumped out of position.
The connections should not turn blue if they are then I would suspect bad contact and that is why after it heats up the resistance also has gone up and the current will drop
You may have to replace the negative connector that has turned blue as if it is corroded or pitted then it will damage every new lamp installed
Also check the air vent in that area I assume you have the large square box with the ignitor mounted inside and a glass tube coming forward to jet some air on the anode

Posted by Paul G. Thompson (Member # 655) on 05-26-2003, 12:20 AM:

If it is a shutter strobe flicker, there could be a diode that may be losing it's ability to perform. If not, I agree with Gordon and Mark. By the way, check and see if the power applied to the rectifier remains at normal levels. Could be a bad breaker, too. I have seen some bus bars get flakey in Square D snap-in breaker panels and it'll drive the line voltage to the rectifiers nuts under load. Remove the breaker and do a visual inspection of the bus bar. CAREFUL - IT'S "HOT"

Posted by Jean-Michel Grin (Member # 1360) on 05-26-2003, 12:07 PM:

Mark,

By the past we used ORC Lamps. It was a lot off troubles with these lamps.
We definitly switched to OSRAM bulbs. No more troubles, a perfect light during all lamp life.
But in one lamphouse, we use USHIO 6000 Watts lamp, without any problem...
The only problem is my poor English; I beg Your pardon for that. [Big Grin]

Posted by Adam Martin (Member # 641) on 05-26-2003, 01:30 PM:

I agree with Mark about the arc wandering. We were using the Osrams in the Imax projectors there and the flickering always started at about 200 hours. Sometimes it got better after a bit, but usually not. I have never been particularly impressed with the higher wattage Osrams because of this.

My recommendation would be to give a 7K Christie a try. I've had quite good results with that lamp in the past.

Posted by Michael West (Member # 428) on 05-26-2003, 02:20 PM:

just like adam, we have the same symptoms with our imax projectors; after about 200 hours they start to flicker a bit and gradually get worse.
once we had it flicker really bad just after the lamps were changed (like ac ripple) but then we started to replace the four plastic insolaters in the lamphouse with every second lamp change and that seems to have helped alot. we also use osram 7kw lamps

Posted by Adam Martin (Member # 641) on 05-27-2003, 01:40 AM:

I just found out that the 7K Christie lamps have been approved for the Imax SR system. Bob - I emailed the technical bulletins to Dan. Michael - Email me if you would like a copy of the bulletins also. I have been extremely pleased with the stability and longevity of the Christie lamp over the Osram.

Posted by Bob Brown (Member # 1205) on 06-08-2003, 02:04 AM:

*****UPDATE******

We just had a Christie bulb installed and it seems most,if not all of our problems have disappeared. The technicians are replacing some diodes on Monday They also noticed that the lamp house did not contain any magnets/ Weird!

Thanks for all the advise [thumbsup]

Posted by Richard Fowler (Member # 893) on 06-08-2003, 02:58 AM:

The Cinemeccanica console was designed for HS type bulbs which normally requires no magnetic stabilizer. The lamphouse module with the glass reflector instead of the metal dichoric I think had stablization but I only remember seeing one early last year; so I don't fully remember. Personally I prefer a magnet, especially when a client installs a bulb type other than the lamphouse manufacturer recommends.
Richard Fowler
Kinoton America Inc.

Posted by Antonio Marcheselli (Member # 373) on 06-08-2003, 07:44 PM:

I've never heard bout this "magnet". What is that?

Bye
Antonio

Posted by Gordon McLeod (Member # 33) on 06-08-2003, 09:24 PM:

To operate a xenon buln horizontally it often needs a magnet to stabalize the arc to stop its tendancy to climb and wander