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Author Topic: Dimmer chaining Dominic Espinosa Phenomenal Film Handler Posts: 1172 From: Boulder Creek, CA. Registered: Jan 2004 posted 07-15-2008 07:19 PM                     Here's a new one for me. I have a theater with a pair of Xetrol dimmers AND a Kelmar dimmer. The Kelmar appears to be the "master" with half the house lights attached to one of the xetrol's and the other half by the other one. For some reason now, one of them is not dimming when the show starts, it has to be manually dimmed by hitting the button on the front panel of the dimmer. Any ideas?  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 07-15-2008 09:06 PM                     The Kelmar control works on pulling the control lines to ground some of the older Xetrols went high Most likely they have added a seperate relay to buffer the two  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 07-15-2008 09:38 PM                     Xetrols just had a 12vac power supply which operated the 'up' relay, or the 'down' relay. The 'common' connection was not grounded. I think Gordon is right; there is nothing wrong with either dimmer, just the relay (or whatever) that operates them both at the same time. If so, that's harder to help figure out because it just depends on how your installer wired it. If you still need help with this, it might help to tell us which dimmer is not working, and go from there. I assume it works OK when the lights are raised?  |  IP: Logged Noel Mackisoc Film Handler Posts: 8 From: Newton, NJ, USA Registered: Jun 2008 posted 07-21-2008 04:12 PM                        You might first check the operation of each individual dimmer by jumpering the appropriate control terminal (up/dn) to its common. This would tell you if the control problem is with a specific dimmer or an external source, such as an isolating relay as John suggests. Yes, the control lines for Kelmar and Xetrol dimmers are incompatible and must be isolated from each other.  |  IP: Logged

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