This is topic Lamp doesn't strike 2 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Antonio Marcheselli (Member # 373) on 04-08-2003, 03:40 AM:
 
Hi everyone.

Yes, I'm still fighting with the same problem! I have a Cinemeccanica lamphouse that is burning lamps.
Lamps become prematurely black, and have problems at striking, particularly when hot.

This time we had the opportunity to check the amperes with an ammeter clamp. When the Cinemeccanica's ammeter says 100A, the ammeter says 148A. The voltage says 32V.
If we set the V at 30 the Amperes are at 135A. 3k lamps should stays at 100A...

Is there that I can deduce from this?

Bye
Antonio
 

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Posted by Michael Schaffer (Member # 1204) on 04-08-2003, 06:11 AM:
 
Yes, Antonio, you can deduct the costs for all those Xenon lamps from your quarterly budget
Where exactly did you measure? Have you checked that all connections in the currency path are proper and tight?
Lamphouses have NO RAM!
 

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Posted by Sam Hunter (Member # 1119) on 04-08-2003, 08:39 AM:
 
Antonio, what model lamphouse do you have? What type bulb are you using and what kind of rectifier are you using?
It wouldn't really be a connection issue would it? The current is apparently too high on the lamphouse. Is it possible that you are having rectifier issues? Maybe a diode or filter has been gone south. I dont know much about Xenon lighting systems and lamp specs but if your handheld meter is correct and you are measuring in the correct place then maybe the regulation device has failed. I would hit the manual and see what the operating specs are and go from there.
Good luck Antonio.

[ 04-08-2003, 07:39 PM: Message edited by: Sam Hunter ]
 

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Posted by Daryl C. W. O'Shea (Member # 1303) on 04-08-2003, 10:39 AM:
 
Sounds like the built-in ammeter doesn't work too well. Adjust the rectifier using the clamp meter so that you've got the correct operating current (100A).

Blackened envelopes and early failure are certainly results of running a lamp at 50 amps over its intended operating current.

If you did add more RAM, would you see a performace increase? Couple fl maybe?
 

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Posted by Antonio Marcheselli (Member # 373) on 04-08-2003, 06:48 PM:
 
Sorry for the typo on my previous message!

Lamp is Osram 3k, Lamphouse is Cinemeccanica 7040H/7 and Rectifier is IREM G3.

Let's suppose that the lamphouse ammeter isn't working properly. So why at 30V I see 140A (on my ammeter, not build-in)? Shouldn't I see about 100A?

The lamp has always difficult to strike when hot.

I've changed the diodes this summer. Do you believe that it could be a capacitor issue?

Michael, I measure at the cable going from the rectifier to the lamphouse.

Bye!
A
 

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Posted by Sam Hunter (Member # 1119) on 04-08-2003, 07:37 PM:
 
I checked on the specs on this type lamp and 32 volts is too high and current will follow accordingly. I checked on the IREM G3 supply and found this information:
http://www.irem.it/en/Rps/RPSset.htm

Anyway, it looks like you need to back off on your voltage feeding that lamp. If you can drop your voltage down to 28-29 volts your current should drop to nominal levels.
My .02 cents worth.
 

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Posted by Rick Long Jr (Member # 541) on 04-08-2003, 09:38 PM:
 
Like Daryl says, you need to back off the current to 100A. It's not uncommon for Cinemeccanica Ammeters to lie to you. Trust the clamp-on ammeter. Don't worry about the voltage, just turn the "steering wheel" on the rectifier counterclockwise, until you hit 100A. The voltage will incidentally fall as well to probably in the 27-30 range. You will continue to kill bulbs prematurley if you run 50 amps hot!
By the way, what kind of clampmeter are you using? I have the Fluke 336. Good for up to 600Amps DC
 

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Posted by Michael Schaffer (Member # 1204) on 04-09-2003, 06:23 AM:
 
Probably in addition to the miscalibration of the amp meter, there is a loose or burnt connection somewhere in the current path.
 

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Posted by Antonio Marcheselli (Member # 373) on 04-09-2003, 06:47 AM:
 
Thanks to all suggestions.

I'll try to set the current for 100A. Last time the lamp didn't strike at that tension/current but it was already "burned".

Is there a way to set the shakemeccanica ammeter?

Bye

Antonio
 

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Posted by Michael Schaffer (Member # 1204) on 04-09-2003, 10:15 AM:
 
Do not forget to check the entire electrical path for loose contacts!!!!
Also check if the lamphouse has enough RAM.

And report to my thread at the top of Film-Yak!

[ 04-11-2003, 07:35 PM: Message edited by: Michael Schaffer ]
 

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Posted by Rick Long (Member # 213) on 04-09-2003, 10:47 PM:
 
If the ammeter is not too far damaged, you can reset the "zero-adjust" screw in the ammeter to agree with your clamp-on at 100 amps or whatever the required bulb current is. It may not zero properly, but when it sez 100 AMPS it means 100 AMPS.

More than likely, from my experience with Cinemeccanica, however, you will find burnt contacts on or around the shunt. This will definetly have an effect on the the voltage dropped by the shunt which feeds the ammeter.
 

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Posted by Randy Stankey (Member # 64) on 04-09-2003, 10:58 PM:
 

quote:

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Michael Schaffer: Do not forget to check the entire electrical path for loose contacts!!!!

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