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This topic comprises 3 pages: 1 2 3
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Author
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Topic: Switching vs. Reactance Supplies
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Don Sneed
Master Film Handler
Posts: 451
From: Texas City, TX, USA
Registered: Aug 2001
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posted 10-16-2001 09:12 AM
HERE,HERE Paul...I totally agree with you, the switcher power supplies I rather not use, but I don't own the company I work for and the owners have the final say, I'm just bthe installer !! but the Strong Switcher Pwr Supply is better now than it was a two years, I did a install in Joplin Missouri & the switcher on a 2K lamp was going out after 20 hours, after we wire the console we run the lamp & Proj for 100 hrs. before opening, we were going though pwr supplies left & right, the theatre was ether a 12 or 14 screen (install too many theatres since then), we had a pwr supply to go out, I changed the fuses inside the switches & fire shot out !!! Not a spark but fire !! When Troy came to align the consoles I showed him, Whoooaaa Weeeee he tripped out, it was the damnest thing I ever saw !!! I now do not ever try to change the fuse anymore, just send for a replacement...Here in Japan I we do not use switcher pwr supply, but in the states over night means over night, in Japan overnight mean 5-7 days, if you are lucky !! But the Strong Switcher is much better now than 2-years ago, we only have 1 out of 12 fail.....much better !! But I still rather use a high reactance where you can service in the field.....ok I'm off the soapbox now....
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Paul G. Thompson
The Weenie Man
Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000
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posted 10-16-2001 02:59 PM
Ken, they were exciter lamps. To be more specific, they were 9 volt 4 amp pre-focused lamps. The soundhead was a Simplex SH-1004.Why the spare lamphouse? Simple. It was already interfaced with the power supply. This eliminated the need for anyone to remove covers to connect or disconnect any wires whatsoever. Just plug it in and throw the switch!! Customers are not to interested in waiting while the projectionist fiddles around 20 minutes or more trying to find out why the lamp doesn't light. But they will probably wait five minutes for you to throw a lamphouse on the pedistal and throw the switch. Each projection station was equipped with a 50 amp twist lock receptical for that purpose.
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Rick Long
Jedi Master Film Handler
Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999
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posted 10-16-2001 09:44 PM
I have to admit that switchers are much more reliable in the last couple of years. A tip to installation technicians - tighten all the connections on the 3-phase twist-lock plug.One interesting problem we have had ONLY with the newer plug-and-pray types (3 instances), is where the rectifier suddenly shoots up to full output. You get to the theatre to find out why a rectifier has been cutting out (thermal) and note that the current to your 4000-watt bulb is 200+ amps! (The potentiometer is NOT the problem, btw). Looking forward to investigating this phenomenon further when I get the time. With so many switcher-rectifier equipped theatres to service, it would be rather expensive to have a unit in each theatre. Better. we find, to keep them in a central location and deliver them as needed. (Yet another reason why technicians always have one arm longer than the other).
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 10-19-2001 07:47 PM
Both Switchers and high-reactance supplies have their uses. The concept of switching power supplies is not inherently flawed...everyone reading this is using a computer that I can just about guarantee is using a switching power supply. Sure there are computers that have their power supplies fail but as a function of usage...not an overwhelming number.That said...I think there are two ways of looking at the situation for permanent theatrical use... First there is no real weight advantage to the switcher since the goal is not to replace it but for it to work. A conventional rectifier is almost always serviceable with minimal time (I say almost since sometimes it is the transformer and most of us don't carry that nor the large filter capacitor though I get the capacitor quickly in a pinch). Certainly, all rectifiers will fail someday...how well your system keeps the ignition noise, power spikes and such away from the diodes will play a big factor on if the diode fails at show start...how well it is cooled will play a factor on how well they last thoughout the day. I'm sure most of the old timers know of rectifiers they have NEVER had to go into yet others that seem like constant repeat customers despite being basically identical designs. The second way to look at things is that using switchers, even with their failures, brings the repair down to the theatre level. That is, have your switchers on plugs and have a spare at each location...at that point, the theatre can simply plug in the spare, send out the defective one and when it comes back...the spare is at the ready. Based on the size of the complex, one should have more than one spare...in fact with the larger plexes 4 spares would not be unreasonable...heck most plexes carry more $$$ in spare xenon lamps. Since no spare xenon nor rectifier means the show won't run both should be on hand. We have one customer that uses conventional rectifiers but has them on plugs as well so when even a diode fails the rectifier can be switched out with virtually no down time. With conventional rectifiers only one per booth is all that is needed (doubtfull more than one will fail and they are servicable at the theatre). My personal vote is to use high-reactance rectifiers whenever possible in permanent installations. Their failure rate is less, meaning less customer dissatisfaction and are repairable on site for quick repair. Switchers can also suffer from semiconductor obsolecense whereas diodes and capacitors can be sourced from several manufacturers for the forseeable future. If you are a rental house...that is a different story...swichers win pretty easily...they are light weight and set up quickly...Strong has theirs done quite nicely with MS plugs and any reputable rental house will have spare switchers at the ready on site (most have a 1:1 ratio of spares to show units). Steve ------------------
"Old projectionists never die, they just changeover!"
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I have Strong 2kw, single phase Switchers in my home screening room and would not trade them for sex. They are GREAT!!!!! (Ummmm that's negotiable..... 
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