Film-Tech Forum ARCHIVE: ORC Lamphouse won't strike bulb

This is topic ORC Lamphouse won't strike bulb 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=004992

Posted by Joe Redifer (Member # 3) on 06-11-2003, 10:28 PM:

Brown/beige ORC lamphouse. 2000 watt bulb. Lamp tries to strike but can never quite get going. Here's the scenario:

Bulb has been changed. Tap settings are right where they should be. Connections are good. No arcing that I can see. I can hear the contactor closing before ignition is attempted. Spark gap looks OK. The syptoms are exactly the same as if you switched the 3-phase "Rectifier" breaker on the console itself off and tried to manually strike the bulb. The bulb tries to strike but never makes it. There was another ignitor laying around and just for fun I tried it. It did not even attempt to strike the bulb. Obviously bad. I put the regular ignitor back in. I checked to see if any breakers were tripped and there were none. I even checked the funky ORC "reset" button on the console. I am not too convinced that it is the ignitor, but for all I know I guess it could be. Any opinions on what it could be?

PS - This is the same lamphouse I had trouble with a little over a week ago with the bad thermal switch.

Posted by Ken Layton (Member # 133) on 06-12-2003, 12:19 AM:

Does the contactor have any burned/pitted contacts? What's the "no-load" voltage you're getting?

Posted by Mike Pennell (Member # 1692) on 06-12-2003, 04:20 AM:

Joe, whats the voltage to the bulb? I've never worked with an orc but i like to blame diodes. Diodes are the work of satan, check them [evil]

then have a beer [beer]

Posted by Gordon McLeod (Member # 33) on 06-12-2003, 10:00 AM:

Most of the ORC rectifiers based on the XPS45 design have 2 large open frame relays that switch the input taps of the rectifier to high at startup and then drop it after ignition It is controled by a plug in relay above the transformers.
Check them and the plug in relay

Also the positive connection to the filter caps is made by a piece of nichrome wire to the positive heatsink (usually the upper left corner screw on the fiberglass frame)
Check it that it hasn't burned off

If you replace it with regular wire you will drastically increase the inrush current to the lamp so I usually just shorten it and put a new crimp on it
I have never founbd a source for the nichrome wire