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Author Topic: Lamp doesn't strike 2 Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 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  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 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!  |  IP: Logged Sam Hunter Jedi Master Film Handler Posts: 779 From: West Monroe, LA, USA Registered: Jan 2002 posted 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 ]  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 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?  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 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  |  IP: Logged Sam Hunter Jedi Master Film Handler Posts: 779 From: West Monroe, LA, USA Registered: Jan 2002 posted 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.  |  IP: Logged Rick Long Jr Expert Film Handler Posts: 211 From: Toronto, Canada Registered: Jul 2000 posted 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  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 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.  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 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  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 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 ]  |  IP: Logged Rick Long Jedi Master Film Handler Posts: 759 From: Toronto, Ontario, Canada Registered: Nov 1999 posted 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.  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 04-09-2003 10:58 PM                     quote: Michael Schaffer: Do not forget to check the entire electrical path for loose contacts!!!! It's a good idea to check all your power supply wires for loose, burned or corroded connections every time you change the xenon lamp. BTW: No Michael, I think he's got plenty of RAM! He probably just has installed PC-100 where he needs to have PC-133.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-11-2003 06:05 PM                     On many meter shunts the leads going to the meter itseld can be moved to calibrate the meter  |  IP: Logged

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