Film-Tech Forum ARCHIVE: Bad power supply/transformer?

This is topic Bad power supply/transformer? 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=007725

Posted by Aaron Wesener (Member # 2046) on 12-31-2005, 07:50 PM:

Hey guys, I have an issue with my Christie SLC Xenon console. The lamp went out mid-show; I checked all of the obvious culprits. I then noticed that the switch for the Xenon power supply was tripped. I reset the switch/breaker after a few seconds it tripped again. I ran a few tests and my 3-phase input power is good but I am not getting proper DC power after the lamp attempts to ignite (85 VDC according to my manual). Just want your input on if this is a bad power supply/transformer, or if there are more tests that need to be done.

Posted by Frank Dubrois (Member # 3042) on 12-31-2005, 09:16 PM:

Have you checked the diodes? Usually when the bulb goes out and the projector keeps running, OR a breaker gets tripped, its a diode!

Posted by Aaron Wesener (Member # 2046) on 12-31-2005, 09:24 PM:

I replaced the three diodes on the negative side, and the ones on the positive checked out OK.

Posted by Giorgio Volpi (Member # 1182) on 01-01-2006, 07:42 AM:

Aaron,
my advice is to change all diodes.
When one fail the others are not in their best condition.
Giorgio

Posted by Frank Dubrois (Member # 3042) on 01-01-2006, 06:33 PM:

That could be true. Its odd that you had to change 3 diodes. I haven't had 3 go bad all at once. I did have one go bad and another that couldn't carry a load. Basically, what that means is it will check out ok, but once you put it back in the projecter, it can't do its job. The only way to track them down is to change them one at a time until you find the bad one, or just change them all. I prefer not to waste the diodes, and invest the time by checking them one at a time. Good Luck. Also, I just wanted to make sure that you are completely disconnecting the diodes before testing them? Leaving them connected to the projector can give you bad readings.

Posted by Aaron Wesener (Member # 2046) on 01-02-2006, 02:04 AM:

All six diodes were changed just after my last post, and I'm still having the same issue. I will test all of the diodes when time permits, but for now I figured that I would just change them all. The lamp will still strike but not light, and the breaker will still kick off. I also checked and I am not getting the appropriate DC output voltage from the transformer/power supply.

Posted by Louis Bornwasser (Member # 3063) on 01-02-2006, 06:30 AM:

Remove the 3 medium sized wires on the diode bridge. Secure the ends so they don't touch anything and apply power. If the breaker trips, you have a bad transformer. If the breaker does NOT trip, you have disconnected the problem.

Then reconnect the 3 medium wires and disconnect the two +- larger wires. Try again. If the breaker trips, something on the diode bridge is wrong; no tripping: something later in the circuit is the problem.

Good luck! Louis