Film-Tech Forum ARCHIVE: Lamp/rectifier/power supply problem.

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Posted by Stephen Furley (Member # 1277) on 03-25-2007, 06:17 AM:

Strange problem yesterday evening. Kinoton lamphouses, Irem rectifiers.

Starting the adverts and trailers for the 6 O'clock show. Just as I opened the curtains the lamp went out; couldn't restrike it. Shut everything down and re-started, lamp won't light. Check the main three phase breaker for the rectifier; it's tripped. Reset the breaker and try again; as soon as the lamp strikes the breaker trips again. At this point the audience has been staring at a blank screen for the best part of a minute, so I abandon the adverts, reset the masking for scope and start the feature. After about five minutes I try to strike the lamp on the problem machine, and it's fine. Try again about 30 minutes later, still fine. Decide that the problem seems to have fixed itself, and go ahead with the changeover to that machine; no problems, and everything was fine with the next, and last, show.

No strange sounds, smells, sparks, smoke etc. from lamphouse or rectifier, but I'm a bit concerned that the breaker should have tripped twice; I've only ever had it happen once, and that was several years ago; I can't remember if it was the same rectifier.

Faulty breaker possibly? I can't see anything wrong with the equipment. The cinema is closed today; I'll e-mail the chief in the morning and let him know.

Posted by Louis Bornwasser (Member # 3063) on 03-25-2007, 04:29 PM:

In USA 3 phase breakers get worn and only 2 connections are made. Then when you strike, it is too much without the third. Is this possible? In any event, I would swap the breaker as a precaution especially if you use it everyday to cut off power when you leave. Louis

Posted by Michael Schaffer (Member # 1204) on 03-25-2007, 07:35 PM:

And, of course, trace and check all the connections visually and mechanically (meaning check for visible discoloration anywhere and loose connections).

Since you typically can't switch between manual and auto strike on the Kinoton lamphouses - at least not as far as I can remember, and it has been a few years since I have played with any of the older lamphouses which I think you have -, it is not easy to check if the tripping occurs when the rectifier is switched on or when the lamp strikes. One way to check that is to switch off the lamphouse with the switch on the back, open the rectifier and push and hold the contactor in firmly (there should be a little push button at the side) with an insulated screwdriver.

Obviously, this is a little [Eek!]

dangerous

when you don't know what you are doing, but I think you are a big boy and you do know what you are doing. Just a standard warning to remind people who read this not to do it unless they are sure they understand the risks.

You just wait for a few seconds and see if anything happens, next you flip the lamphouse switch to on and see what happens then. That should bring you a little more clarity.

If I remember incorrectly, it may also be that the contactor pulls in when you run the motor, even if the lamphouse is switched off. But I don't think so. In any case, you should close the big douser on the front, if you have it and/or run the motor anyway because it's not good if the lamp comes on when the front of the lamphouse is open and the machine is not running.

Posted by Demetris Thoupis (Member # 833) on 03-26-2007, 01:54 AM:

What we call it in greek is "apolia", loss in connection or something like this in the electrical speech! It means that you either have some humidity build up in the breaker or the cables or the piping or the connections that make a small contact between each phase or a phase with a neutral of a phase with the earthing that causes the breaker to trip. Probably the humidity dried out after a while and that is why the breaker stood up! I don't know if I explained it correctly.