Film-Tech Forum ARCHIVE: Is there a way to up the open circuit voltage/Irem Rect

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Posted by Brad Allen (Member # 470) on 05-19-2005, 03:55 PM:

The Irem rectifier I have, I measure 78v open circuit. Rating plate shows 75v, so I assume it's within spec. Is there a way to increase this voltage? I understand that 100v is more desirable. Trying to cure hard starting of bulb.

Posted by John Walsh (Member # 168) on 05-19-2005, 04:45 PM:

Most do not allow adjustment of the no-load voltage. 75V should be OK for a 1.6K - 2K bulb. Have you looked at other causes of hard starting, like the RA relay, etc.? I recently had an issue where the operator had turned down the current to save bulb life, but it was too low to provide enough current to get the bulb to light reliably.

Posted by Richard Fowler (Member # 893) on 05-19-2005, 05:06 PM:

Besides the RA relay, since you have Xenex I units, you can change the zener diode on the auto-strike board for lower no load voltage.

Posted by Louis Bornwasser (Member # 3063) on 05-19-2005, 06:59 PM:

You can test the RA relay theory by TEMPORARILY unplugging the relay and connecting black wires together and red wires together. If everything works OK, then you know the relay was the problem.

Just don't leave it this way....bulb life will be shortened. In my experience, I have never seen low open-circuit voltage as a problem with IREM.

Posted by Marin Zorica (Member # 1716) on 05-21-2005, 12:28 PM:

Can you even strike xenon lamp? What is current when is on? Is it normal?
If isn't maybe one of diodes is dead?
Also look at filter capacitor, maybe is bad, just try to put some capacitor in serial

Posted by Brad Allen (Member # 470) on 05-21-2005, 01:08 PM:

Ok, I"ll plead ignorance. What does RA stand for? Are you talking about the relay on the auto ignitor board?

Yes, lamp will light, but can take 3-5 attempts at times even with a new bulb. It's always been this way.

Cap's arn't very old.

Posted by Steve Guttag (Member # 268) on 05-21-2005, 02:56 PM:

I believe that "RA" was just IREMs designation for relay. Most use "K" for relays or some use "RL" but those that work with IREMS know the "RA-Relay", often pronounced "rah-relay". It is there to help with the ignition of the lamp by switching in and out capacitance. A big clue to its failure is if the lamp strikes and immediately goes out (as the relay switches out).

Posted by Mark Gulbrandsen (Member # 72) on 05-21-2005, 07:59 PM:

Brad,

What exactly is your line voltage there? I've only had problems with IREMs no load voltage when the line voltage was low as in a brown out condition. During brown outs the current had to be upped to get em to start reliably and then quickly turned back down to normal current after ignition.

Mark

Posted by Brad Allen (Member # 470) on 05-22-2005, 01:24 AM:

I'll have to check on the line voltage. It's been a while since I checked it and don't recall.
Thanks all.

Posted by Brad Allen (Member # 470) on 05-26-2005, 02:58 PM:

Line voltage @ 3:30pm local time was 121.7

Posted by Mark Gulbrandsen (Member # 72) on 05-28-2005, 11:01 AM:

Brad,

That seems a tad low to me for that line voltage level.... I seem to remember these being around 95 to 100 volts no load. I gotta wonder if the relay board is bad.

Mark

Posted by Brad Allen (Member # 470) on 05-28-2005, 12:49 PM:

I'll tear it apart and check out the relay board next wk after the holiday. Thanks Mark and all.