Film-Tech Forum ARCHIVE: Problem Associated with the Strong Compact Model 62-80109 Rectifier

This is topic Problem Associated with the Strong Compact Model 62-80109 Rectifier in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=004975

Posted by Aaron Mehocic (Member # 15) on 06-07-2003, 03:37 PM:

Need some advice on this one . . .

Recently our Strong 62-80005 rectifier blew and it was replaced with the model featured in the title. In my opinion both types suck, but thats neither here nor there. Since installing the newer rectifier, the bulb's arc (ORC XM2000H/VC/G) has a wierd swirling motion to it for about five to ten seconds upon ignition. Afterwards the arc normalizes and runs perfectly for the rest of the show. The bulb has less than 200 hours, the current is reading 75 amps (Super Lum-X lamphouse), and everything else is as it should be. This swriling is something I've never seen before, but my hunch is the current level will probably need increased or decreased for a period of time, or possibly forever. By adjusting the current, however, it will affect the brightness of the entire run. All I want to do is eliminate the swirl.

I appreciate any help you might offer.

Posted by Mark Gulbrandsen (Member # 72) on 06-07-2003, 04:30 PM:

Aaron,
I have had so little problem with Strong switchers that I pretty much swear by them. There are literally thousands of them working day in and day out in the field! In fact we just installed 8 of them in a new plex we are working on along with Big Sky lamphouses. Strong Switchers are extremely reliable, even in areas with iffy power conditions, and they give excellent lamp life.

IMHO your problem most likely lies in the brand of lamp that you are using. ORC lamps have THE WORST reputation here in the States, and as far as I know the 2kw lamps come out of China. Perhaps another Film Techer can confirm that.....

Use a reputable lamp such as Christie/Ushio, LTI, or Superior Quartz (prefreed in the order listed). There are no other usable, reliable brands of lamps in my experience.
Mark

Posted by Rick Long (Member # 213) on 06-07-2003, 08:48 PM:

Okay, so whats gonna make an sealed arc swirl (or move at all for that reason)? Only thing that comes to my mind is a magnetic field that is moving and fighting the effect of the lamp's magnet.

Is it possible that this particular rectifier has a low-frequency sweep in the D.C.?

You can confirm this by switching rectifiers with another theatre in the complex.

Posted by Aaron Mehocic (Member # 15) on 06-07-2003, 09:16 PM:

Thats the question: What makes this arc swirl. I'm now seriously concerned with the possibility of explosion. Unfortunately every show in this particular auditorium has ran today and the crunch schedule does not allow for any inspection time.

Mark, I hear you in that Strong makes some excellent products, but I'm not so sure I'd put rectifiers on that list. In 1996 I had four houses running this brand rectifier. Now that number has been cut in half; and I'm figuring after this, by 75%. Also you are right about ORC bulbs in that the quality in those isn't as good as a Christie (which are my favorite too). Unfortunately, I'm stuck with ORC because thats what we buy because they are cheap. Still, I don't think its the bulb since, in my opinion, it should have done this from its own installation and not the rectifier's.

Rick, tell me more about this DC sweep.

Posted by Rick Long (Member # 213) on 06-08-2003, 01:26 AM:

Asumming this is not a defective bulb:

To be perfectly honest, I am not sure, but it seems to me that the only thing that could affect the arc flame in a sealed bulb is the magnetic field itself.

This magnetic field is derived from
(1) The permanent magnet in the arc lamp, usually bolted to the floor of the lamp forward of the reflector.
(2) The magnetic induction of the arc itself.

It seems to me that these two fields work to place the arc directly on the anode where it should be, and that any variation in either of these fields could alter the position of the arc flame.

Steady-state DC from the arc should result in a steady flame. If, on the other hand the D.C. to this arc was fluctuating, perhaps too fast to be accruately read on the D.C. ammeter, or seen on the screen, then perhaps this swirling effect could be created.

This could easily be proven by substitution methods, first the lamp, then the rectifier.

Interestingly enough, I have noticed a number of over-life bulbs which I have removed, recently, to show signs of severe a.c. ripple.