Film-Tech Forum ARCHIVE: Dimmer Problem

This is topic Dimmer Problem in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by James Ness (Member # 4631) on 01-29-2010, 08:56 PM:

So we have these Drive-In Theater Mfg. Co LD-35 dimmers
and we've had one thats been not completely functioning for a while, it will only manually dim using the dial.
We had another in a different theater go out today and you can only turn it all the way on or all the way off using the ON/OFF switch, none of the other controls do anything.

Can anyone help? This is a huge pain!

Posted by Tony Bandiera Jr (Member # 2365) on 01-29-2010, 10:44 PM:

The first one has some sort of problem with the automation interface, check out the connections at both the dimmer and automation to make sure they're correct, also check that the automation is sending the pulses (or contact closures) as it should.

The second dimmer has a shorted triac, which will need to be replaced AFTER you carefully check ALL of the luminares in the auditorium and make sure none are shorted out (most common cause for blown triacs in dimmers.)

Posted by Gordon McLeod (Member # 33) on 01-30-2010, 12:09 AM:

disconnect the automation and see how it behaves
the triac may be shorted in the second one or possibly the driver has failed