Film-Tech Forum ARCHIVE: XPS-16S ORC Power Supply Drawing Too Much Current..

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Posted by Paul G. Thompson (Member # 655) on 11-17-2003, 01:52 AM:

First one I ever had this problem with.

Open circuit voltage is high enough to fire the lamp igniter, but I don't know what the voltage is. However, the bulb current is low. About 50 amps. About 10 seconds later, the main circuit breaker trips.

All diodes are fine. Nothing wrong with them. The reactor has no short circuits to ground. Neither does the power transformer.

There is not a whole heck of alot of things that can go wrong in this thing. It is one of the most straight forward xenon power supply units I have seen.

I have not checked the power supply for current draw off the AC line under a no-load condition yet, I might do that tomorrow.

It was a power supply that died in the middle of a show some time ago, and I finally got around to working on it. Thought I had it repaired but during the testing phase, that was not so.

Maybe one or two of the electrolytic filters may be shorting out. I don't have a capacitor checker that will even look at a capacitor that large. I don't have any spare electrolytics. I don't want to buy any unless I know it is the problem.

Anyone ever ran into one like this?

Posted by Mark Gulbrandsen (Member # 72) on 11-17-2003, 04:00 AM:

Paul,
To check the electrolytics disconnect them one at a time and check the current draw with the supply turned on just briefly. Don't leave it on long enough to possibly blow the overpressure vale on the capacitor if one is shorted...makes a big stinky mess!

Mark

Posted by Paul G. Thompson (Member # 655) on 11-17-2003, 09:44 PM:

I found my old Sprague 10-6 Capacitor analyzer and charged the capacitors up to 50 volts (the working voltage of the capacitors) and they only showed 1 millamp of leakage per capacitor after the full charge was obtained.

I guess I'll have to put an inductance checker in the power transformer and inductors to see what the kick is, and compare it with a good power supply. I have a hunch that I will find a problem with the power transformer.

Any other suggestions?

Posted by Dave Macaulay (Member # 813) on 11-17-2003, 10:09 PM:

The most likely problem given everything you've found OK is a shorted section in the transformer. Sounds like you already surmised that.
I find these fairly often in failed electronics, it seems like a transformer should be pretty failureproof but apparently they aren't. I've only run across a few cases of rectifier transformers going bad but it happens. Usually it retires the rectifier and provides a few spare parts.

Posted by Paul G. Thompson (Member # 655) on 11-17-2003, 10:34 PM:

Dave and Mark, I'll zap the transformers and inductors probably tomorrow. I'll post the results.

I agree with the transformer thoughts mentioned by Dave. In the past 20 years, I have had several L-1 failures but no rectifier transformer failures.

I hate to junk those old XPS's. They are good power supplies, easy to work on, and the only thing that seems to go wrong is diodes and contactors. Plus, they don't weigh 16 tons. [Smile]

For it's physical size as a reactance power supply, it is a remarkably powerful and reliable unit. They will handle 75 amps without even breathing hard.

Posted by Paul G. Thompson (Member # 655) on 11-18-2003, 02:24 PM:

According to the inductance check, it is indeed a rectifier transformer problem. There appears to be a leakage between the primary and secondary windings.

Posted by Ken Layton (Member # 133) on 11-18-2003, 06:26 PM:

Some ORC transformers are still available from Strong. Do you have a part number for the bad one?

Posted by Gordon McLeod (Member # 33) on 11-18-2003, 07:59 PM:

Some of the ORC transformers are available from LP Associates

Posted by John Eickhof (Member # 323) on 11-18-2003, 09:54 PM:

If not Leonard Pincus (LP) or Strong, Dick Niccum designed this one while at ORC, he may also have transformers or specs on them! Contact Dick at RichardNiccum@aol.com

Posted by Paul G. Thompson (Member # 655) on 11-20-2003, 11:26 PM:

I had one laying around in the back room. Thanks, Ken, Gordon and John. [Smile]