Film-Tech Forum ARCHIVE: Xenon Lamp Problem

This is topic Xenon Lamp Problem in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jack Culpepper (Member # 724) on 04-23-2003, 12:31 PM:

I had a Canrad-Hanovia 1.6KW lamp removed from an ORC X-2500 lamphouse. When I first used this setup, it seemed to have worked o.k. The image brightness on the screen was perfect. The lamp pulled about 70 Amps. After about 3 years of use, I one day turned the projector on and noticed that the screen image brightness was less. The lamp was only pulling 45 - 47 Amps. Research indicated that a new bulb was probably needed. I ordered and received a new Ostram-sylvania XBO 1600W/HS as a replacement. The new bulb was installed. All attachments were properly made. The lamphouse was turned on and the only thing that happened was a loud POP-POP-POP-POP-POP. I quickly turned off the lamphouse and waited about 10 minutes. I turned the lamphouse back on and the samething happened. The lamp never did strike. After the new lamp cooled, it was removed and inspected. No damage seems to have happened to the new lamp. No discoloration occurred. Any information of what is happening and a solution will be most appreciated.

Posted by John Spooner (Member # 1565) on 04-23-2003, 12:54 PM:

Dear Jack. The sudden drop in lamp current as well as the inability to strike the new lamp suggests a power supply fault.
Either a faulty rectifier diode(s) or the current regulation circuit has failed. The HV striker circuit is still ok if you can hear it as you stated.
I had the same problem occur with a Xebex power supply and upon investigation found a dry solder joint on the regulator pcb. I remade the joint and all was well.
Regards John Spooner.

Posted by Paul G. Thompson (Member # 655) on 04-23-2003, 02:09 PM:

The popping sound was probably due to the positive lead from the igniter was too close to the mirror and it arc'ed off. There is a good possibility the igniter has also been blown, but I doubt that. Check the open-circuit voltage of the power supply, but make sure the igniter is disabled before you do that. Otherwise, you will probably toast the meter if, for some reason, the igniter fired.

The open circuit voltage will vary from power supply to power supply. But if you get 100 volts or so, that should be high enough.

If your current fell off that bad, I would have checked a few other things. There could be a power supply malfunction.

In order for us to determine what actually went wrong, please tell us what model power supply you have. I would guess since you have a 2500 lamp, the power supply would be an RPS-2500. Just a guess....Those power supplies can do some nasty things to you that will make your day miserable.

There is a temperature limit switch inside that power supply. Those have been a troublesome device. Also, there are (if I recall correctly) three fuses on that power supply. One main fuse, and two little ones. I'll bet the arc-off of the lead to the mirror took out one of those fuses. Check them with an ohmmeter. It should be noted that the 2500 power supply has the ignition control relays inside the power supply instead of on the igniter. That power supply can be a real bear to troubleshoot without a schematic. ORC did some off-the-wall electrical/electronic designing of that thing.

If you have a schematic of the power supply, scan it in and send it to me, and I will be more than happy to step you through on how it works and what to look for.

Posted by Gordon McLeod (Member # 33) on 04-23-2003, 08:37 PM:

Often the high voltage could be flying to the dowser try striking it with the dowser open to confirm

Posted by Paul G. Thompson (Member # 655) on 04-23-2003, 11:38 PM:

Gordon, that is entirely possible, and I failed to mention that.

Also, it is possible the anode lead is too close to the lamp frame itself. Some Xenon bulb anode cables are just simply too long. Just tie the anode cable into an overhand knot, and that seems to make it "just about right." [Wink]

Posted by Gordon McLeod (Member # 33) on 04-24-2003, 12:13 AM:

The HS doesn't have it's own lead that would be a HSC

Posted by Paul G. Thompson (Member # 655) on 04-24-2003, 12:31 AM:

The cable thing was just a general information statement.