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Author Topic: 4K lamps - Osram Vs Ushio Chris Byrne Expert Film Handler Posts: 102 From: Kirwan, Australia Registered: Jan 2003 posted 03-06-2004 06:36 PM                     I don't want to enter yet another debate about which bulb is best, but I do have a specific enquiry regarding both OSRAM and USHIO bulbs. I am running only one cinema that uses 4K lamps and when told a change to Osram was for the better I dived at the chance. From day one a brand new 3600HN lamp (ushio) would develop a slight flicker (not overtly noticeable on screen until around the 2000 hour mark.) On the other hand the 3600w/htc lamp (osram) starts out with brilliant light, yet the last and only two I have used have started to develop a noticeable flicker around the 1200 hour mark. Equipment used is a USHIOKCX140U4 rectifier and Xebex Supersol(N) lamphouse. The two Osram bulbs that I have used have both arrived with anode lead attached, however I am told this is not a standard purchase. Is there any difference to the bulb that comes separate of the anode lead? I am thinking seriously about swapping back to Ushio, should results not improve with the 3rd Osram I have on order. One thing that I can't deny is that others have had better results with the Osram style xenon.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 03-06-2004 06:45 PM                    Have you measured the ripple on this unit? Is cooling adequate?  |  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 03-06-2004 07:22 PM                        You said you were using 4kW lamps. Both lamps you listed are 3.6kW lamps. Are you sure you are running the lamps within (or around) their operating range of 120 amps (min 80, max 130)? I believe the warranty life on the Osram is either 800 or 1000 hours. The Osram lamp is supposed to come with the lead attached. I've had good luck with the XBO 4000W/HS. If you can handle the larger anode and cathode base sizes, you may want to try one out.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-06-2004 07:38 PM                     Some of the SUpersol Lamphouses had a adjustment for the current in the electromagnet for stabalization Also are you using the standby mode on the sanrex rectifier?If it is the SCR styled and the standby is set below 1/2 the rated current the ripple is very high and flicker will result  |  IP: Logged Chris Byrne Expert Film Handler Posts: 102 From: Kirwan, Australia Registered: Jan 2003 posted 03-08-2004 01:15 AM                     Hi Guys, Thanks for your help. Firstly I haven't checked the ripple and don't know how. Can anyone supply a link or give instruction how to do this? Secondly the cooling is fine. It is regularly cleaned and checked for airflow. An engineer tong tested the current flow and found a 4A differential between rectfier and lamphouse meters. I never run the lamps above 125A (within specified range.) We don't have Standby mode operational on our lamphouses, but what is the SANREX SCR you are talking about? Also, while I know the bulbs are 3.6KW, I have been informed that they are now all referred to as 4K lamps. Is this untrue? Thanks again  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-08-2004 09:33 AM                     Sanrex made 2 types of rectifiers commonly for use with the Xebex lamphouses (at least the ones over here) One style the older was a magnetic amplifier style using a saturable core reactor to regulate and adjust the output current The later ones used a 3 phase SCR bridge to allow current adjustment The problem is if turned down to far the output becomes very dirty from the chopped wave form But since you are not using standbye then that isn't an issue To measure ripple measure the AC component across the meter shunt  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 03-08-2004 09:58 AM                        Another way to measure ripple is to let a bit of the light leaking from the lamphouse shine on a silicon photocell with a resistive load, and look at the ripple on a scope: http://www.sylvania.com/business/photo/pdfs/ENGR_BLTN11.pdf Osram XBO Theatre Lamp Technical Manual See pages 17-18.  |  IP: Logged

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