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Author
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Topic: Help with a XENON SUPPLY
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Matt Close
Expert Film Handler
Posts: 226
From: Hervey Bay, QLD, Australia
Registered: Sep 2001
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posted 04-23-2002 10:28 PM
I have a Eprad xenon supply that exhibits the following ....
I have tested the outputs of the three-gang auto-transformer , and I get between 200 - 300 volts out of each one measured between terminals 2(neutral) and 3(active). Out of the the three-phase transformer, I get 20-30V from each one, and with the small boost supply wires dis-connected from the main DC output, I get around 80V un-loaded. Testing the boost supply output separately reads around 90V at switch-on, then ramps up to 180V and stays there. Someone has replaced the original relay/reed switch combo for isolating the boost supply with just a resistor at some stage .... how does this work?? Also, The lamp-house igniter seems to function fine ..... What I have on the indicators on the rectifier is a yellow fault light, marked IGNITER OR XENON LAMP...... BUT, I ran this lamphouse this morning on one of our IREM rectifiers, and it fired up fine ..... so, any ideas????? ***cries for help*** I've tested all the diodes out of circuit with a meter and they check fine 
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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 04-24-2002 04:31 AM
Matt, it has been the better part of 25 years since I have fooled with an Eprad power supply. So, I am only guessing.First, if you have an open circuit voltage as you describe, I don't think you have a power supply problem. Second, I would look at your igniter. It should have fired. It could be that your zener diode is going goofy, or maybe the igniton relay. Third, did you try to fire it manually? I think Eprad's lamphouse had an auto-strike adjustment, but I could be wrong. If your input line voltage might have been low and your auto strike adjustment might have been at the upper end of the threshold, I could see your problem one night and then be ok the next day. It might be worth looking into. Most xenon power supplys (with the exceptipn of the switchers) are basically identical. Some (but not too many) used a blocking diode, but that is really the only difference. If the blocking diode is leaky, it will cause the open circuit voltage to have a shitty day. But in Eprad's case, I cannot remember if they used a blocking diode. Please provide the model number of the lamp and power supply, and maybe some of us can help you nail the problem down. Paul
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Matt Close
Expert Film Handler
Posts: 226
From: Hervey Bay, QLD, Australia
Registered: Sep 2001
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posted 04-25-2002 06:40 AM
Guys, thanks for all your advice .... but for now , I have shelved the power supply we were talking about, and now am working on another of the same model ...... it only had a shorted brigde rectifier on the output of the small 88V transformer.... however, it runs the lamp happily for a few minutes, then the amperage starts to drop.... you can keep winding the current up on the power supply, until you have no more to give , but the amperage keeps on dropping until the lamp shuts down.... any ideas on this one? (btw, the lamphouse is the 47000) This supply and lamphouse just came from another of our cinemas, where they run 1600W lamps....... we run 2000W lamps.... the supply is rated at 80amps max, so it should work ok, yes?
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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 04-25-2002 01:55 PM
Gordon beat me to this one, but yes, I agree---something is overheating. Check your diodes to make sure they are tight, and also take a close look at your diode leads and look for burned wiring. Check the connections on the filter capacitors, as well as all your connections and terminal blocks for the DC lines to the lamp.In a short sentence, check all your connections.
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