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Author Topic: Kelmar Deluxe Dimmer Problem Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 10-17-2012 08:46 PM                     My Kelmar dimmer had recently had some issues. When the circuit breaker for the house lights is powered on, the led's on the dimmer light up normally and the house lights come on in the HIGH position. However, when the automation pulses the dimmer for MID or LOW, or if the buttons on the dimmer are manually pushed, the LED changes into the desired lighting level, but the lights do not dim! The low level knob on the dimmer is in the lowest setting. The bypass circuit is not wired. After powering off and back on, the problem is still there. Any ideas?  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 10-17-2012 08:51 PM                     Yep the Triac for the output is shorted. Check all your attached lighting for shorts and if they are ok replace the triac and you'll be happily dimming again.  |  IP: Logged Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 10-17-2012 09:12 PM                     You mean check the actual light fixtures for shorts? There are 8 recessed lights in the auditorium. How exactly can I check this?  |  IP: Logged Richard May Phenomenal Film Handler Posts: 1057 From: Floral Park, NY USA Registered: Aug 2004 posted 10-18-2012 06:49 AM                     It usually happens when they are changing bulbs with the lights on. The bulb breaks in the socket and shorts. Takes the triac out all the time. See if any bulbs are broken or blown. Then ask if they broke any while changing them.  |  IP: Logged Stephen Frazza Expert Film Handler Posts: 161 From: Nutley, NJ, USA Registered: Mar 2004 posted 10-18-2012 08:36 AM                        I agree. 99% of the time, any problems I have with Kelmar dimmers it has been the triac.  |  IP: Logged Richard Hamilton Phenomenal Film Handler Posts: 1341 From: Evansville, Indiana Registered: Jan 2000 posted 10-18-2012 09:17 AM                     Why is this in the "Digital" forum? Are Triacs and lightbulbs digital now? Maybe there should be a "Tech-Forum" for issues that affect both film and digital?  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 10-18-2012 03:30 PM                     It's here to make you ask why Richard. Yep, good point on the changing bulbs issue....that is a #1 cause of triac failures any any dimmer. Also, in rare cases, when an incandescent bulb blows it can create a momentary short that can take a heavily-loaded or marginal triac out. Tom, only real way to test for shorts in any given fixture is to disconnect each one and use a meter on the ohms setting, checking for shorts hot to neutral, hot to ground and neutral to ground. It is a job for an electrician in most cases.  |  IP: Logged Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 10-18-2012 05:28 PM                     Thanks for the suggestions. Here is what is weird...this has happened once per week for the past month. The problem lasts for one day forcing us to turn the lights off and on with the breaker during shows. Then the next day it works normally. This is the case again today. Dimmer has worked perfect all day. Not sure how this is possible.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 10-19-2012 12:46 PM                     Ok, other things to check: Swap a control board from another auditorium and see if the problem moves with the board. If so, bad control board. If not, bad triac is still #1 suspect. Best advice for now though is get an electrician in to check for proper voltage coming in to the dimmer, and any loose connections in the breaker panel feeding the dimmer as well as the feeder to that panel. Also try disconnecting the automation wires next time it acts up. If it works normally with the automation disconnected, then your automation has a short or bad relay.  |  IP: Logged Jim Cassedy Phenomenal Film Handler Posts: 1661 From: San Francisco, CA Registered: Dec 2006 posted 10-20-2012 02:41 PM                     Several years ago I had a problem at a very old theater where the original motor driven autotransformer type dimmer had been replaced with a solid state one which blew triacs every few months. In this theater, rather than wire a new control circuit from the auditorium to control the full-power 'cleaning lights', they had decided to keep the original set-up, which used a double pole switch key switch in the back of the auditorium that switched the houselights from the the dimmer output to an entirely different 120V circuit. Most of the time, this switching took place after hours when the janitors came in, but there were occasions when it got switched at full load and that would somtimes blow the triac. We eventually 'solved' the problem by inserting a huge filter choke , which we made from one of the big transformers out of an old arc rectifier, into the dimmer output circuit. This worked to 'absorb' the spikes when the house light circuit was switched to or from the dimmer under load conditions. We did this almost two years ago, and as far as I know, they've never had a triac blow since. (Or I've had heard about it!) Obviously, if anyone else tries this, you've got to make sure the windings of whatever you're using to make the 'choke' coil can handle the full amperage load of you lighting circuits or it will overheat or burn up.  |  IP: Logged Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 10-23-2012 12:04 PM                     Ok, so I still have not determined the problem. But, I have more interesting info. The dimmer only acts up on Sundays. A church uses the auditorium on Sunday mornings so the dimmer is turned on at 7am and by the time we show movies around 1pm the dimmer does not dim! The dimmer then does not function properly until Monday after it has been turned off overnight. Then it works fine until the next Sunday. Here is what is interesting. Last night I left the dimmer on in that auditorium overnight because we were getting our floors waxed. When I came in today, the dimmer would not dim! So, apparently, when the dimmer is left powered up for several hours without the lights being dimmed, it seems to not work. I don't get it...  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 10-23-2012 06:33 PM                     Ok, so something is overheating and not allowing the dimming action. Still leads me to the triac as #1 suspect, BUT I would try moving the control board to another auditorium, leave it on all night in that other auditorium and if it doesn't dim, the control board is bad. If it DOES dim...triac in the first (problem) house is bad.  |  IP: Logged Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 10-23-2012 06:37 PM                     Ok I'll give it a try. Thanks!  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 10-23-2012 06:55 PM                        These are electronic dimmers. SOMETIMES wiring can be an issue. The voltage wire is probably correct. The neutral must be isolated and exactly parallel the hot wire. 20 ft from panel to dimmer and 50 feet to load; the neutral should be the same. I have seen shared neutrals and neutrals that were teed off that worked strangeley. louis  |  IP: Logged Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 10-26-2012 03:23 PM                     First I would like to thank everyone for the help. I replaced the triac and the dimmer now works great. To make sure, I left the house lights on overnight and when I came in today it worked. I'll keep the triac in mind for future issues. Thanks again!  |  IP: Logged

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