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Topic: Kelmar Dimmer not dimming

Tom Kroening
Expert Film Handler

Posts: 214
From: Janesville, WI USA
Registered: Oct 1999

posted 03-16-2001 02:43 AM

Hey all, have an interesting problem. Our old kelmar dimmer stopped doing its thing a few weeks ago. You'd try to dim the lights and nothing would happen. The indicator light would go to low then pop back to high. I first just turned the dimmer off at the breaker for each show. I finally had a chance to open her up and play around. Now when you press dim it does nothing for about 3 seconds then goes totally black. When at medium or high the lights pop back on and blink on and off rapidly. Anyone think it can be fixed? Probably just time for a new unit.

Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 03-16-2001 06:48 AM

Tom -- you need to get yourself one of these:

It's a Ward-Leonard dimmer board from about 1933 and was in use until last spring.

David Hitt
Film Handler

Posts: 9

Registered: Jan 2000

posted 03-16-2001 08:15 AM

Hi Tom,

Assuming the wiring connections to your dimmer are still tight, I'm betting that it's triac is shot. It's probably time for a new dimmer.

David

Ken Layton
Phenomenal Film Handler

Posts: 1452
From: Olympia, Wash. USA
Registered: Sep 1999

posted 03-16-2001 09:16 AM

Have you tried contacting Kelmar (www.kelmarsystems.com) and discussing the problem with the service dept?

Could the automation be causing a problem? Temporarily disconnect the automation leads from the dimmer and try pushing the manual dim/raise buttons on the dimmer to see if it now works. If it does, then your automation is goofy.

If the dimmer still doesn't work, then the triac inside the dimmer is likely bad. These triacs generally cross reference to RCA SK series, Phillips ECG series, and/or NTE Electronics' NTE series of replacement components available at local electronic component distributors or mail order companies like MCM Electronics or Mouser Electronics.

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 03-16-2001 03:01 PM

Hi Tom,
Is one of the Kelmars at the Rock? If so swap triacs as these are two channel dimmers. That will answer your question. If it still stays up you'll hvae to get a new PCB for it. Don't you have a repair guy anymore?
Mark @ GTS

Neil Fish
Film Handler

Posts: 16
From: Norwalk, Ct
Registered: Dec 2000

posted 03-16-2001 03:30 PM

I agree, the first place to start looking is the triac. Definitely NOT time for a new dimmer. A replacement triac can be had for around $30. Generally, Kelmar products are bulletproof, and all components are mil-spec right down to the hardware, which you will find is stainless. Andy Marglin (the Mar part of Kelmar) is very conscientious, and his staff is always helpful, so if the triac doesn't do the trick, give them a call.

Tom Kroening
Expert Film Handler

Posts: 214
From: Janesville, WI USA
Registered: Oct 1999

posted 03-16-2001 04:37 PM

Mark, yes its one of the triacs at the rock. Unfortunately our company doesnt have a tech. Most of our repairs are done either by me or another projectionist that only works about once every two weeks. He used to be in charge off getting all this stuff fixed until he found a better paying job. Now all we have is MTS... from what i hear they said they will not fix it but they will install a new one. BTW yes its only the stage lights that dont work properly, the house go up and down still. Also, what exactly does a triac look like so i can try swapping it tonight?

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 03-16-2001 05:33 PM

Hi Tom, I definately admire you for your dedication to that place. It seems like, but it doesn't surprise me that "the boys" have eliminated all semblance of order around there as far as projection is concerned. The Rock was once a really great place to see a flim and I hope it still is.

Don't believe a word of what MTS tells you! They are so full of hogwash its pathetic. Quality work to them is a rats nest of
wiring and cigarette butts inside the back of a sound rack. I've seen the backs of allot of the racks they did for Edwards...Woof!
Kelmar still makes and sells lots of those dimmers and it's a really great piece. No need to replace it. Apparently MTS just doesn't have anyone with enough brains to take care of it.

The triac is a piece of cake to find. Its red colored(usually) and has three wires that attach with push on terminals. Both of them are mounted to the heat sink thats on the side of the dimmer, and each is secured with two screws. Be sure to note where the three wires go before you remove them so you get em back where they belong. After U switch the triacs,If the problem goes to the ceiling lights, then you know its the triac. I can get you one from Kelmar if you need one, or you can probably pick one up in Madison at that electronics supply place on the SE part of town....can't remember the name. If the problem still persists and the red LED's follow which switch you push, then there could be a problem in the control card....which can also be fixed quite easily.
Good Luck, hopefully this helps.
Mark

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 03-16-2001 08:11 PM

Since it will fade out (then go back up) indicates the TRIAC is working since it is following the ramp
It aslo indicates the ramp generator is working
When it comes back up does it snap up or fade up
If it fades up I would go looking in the automation for a jammed relay
disconect the lv cables and try the manual buttons
Also check that none of the manual buttons have gotten jammed under the cover

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 03-16-2001 08:35 PM

Gord, If a relay is stuck then the LED's on the touch buttons would also be stuck. I ahve seen triacs fail that do not short but snap on and off.
Mark @ GTS

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 03-16-2001 08:52 PM

The led's on the buttons should flash the command as they are clocked on the tailing edge they will then revert back after the debounce time has occured.
Triac failures usually are either shorted or open (like a CFS diode

)

Tom Kroening
Expert Film Handler

Posts: 214
From: Janesville, WI USA
Registered: Oct 1999

posted 03-17-2001 12:44 AM

Excellent, thank you very much. I have about a half hour to play around with it tomorrow morning before the doors open (if i wasn't an usher i'd still be there right now taking a look at it). I'm willing to bet is is the triac from the symptoms you described. It could possibly be from extra wear and tear from those damn sound sync'd slide projectors the set the lights to medium every time it goes around. I'm on spring break this week so i wouldnt have a problem making a trip to madison so long as they pay for gas. If not, ill certainly recommend we get one from you, Mark. I just wish people were taking care of these machines. Today the projectionist came and got me and showed me that one of the film gates didn't spring closed. After getting all of the gunk build up out of the way and lubing the track, worked like new. I have a strange feeling that the other projectors have gunk everywhere too.

I'm busy enough sweeping popcorn!

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 03-17-2001 08:54 AM

Another point about Kelmar is that they are very resonable about their parts prices. Their triacs are realatively cheap.

Based on the description you gave, I tend to vote for the contoller rather than the triac but the triac is certainly the easiest thing to swap. I recently had a triac that turned into an SCR so it would go between half and full....NEVER off.

Kelmar will also repair their controller boards so no need for a new dimmer.

Steve

------------------
"Old projectionists never die, they just changeover!"

Tom Kroening
Expert Film Handler

Posts: 214
From: Janesville, WI USA
Registered: Oct 1999

posted 03-17-2001 11:33 PM

Arg!!! swapping the triacs didn't help... back to square one. I told one of the managers to call Kelmar directly and describe the problem and ask if a controller card would help... There's not much more I can do other then install parts if and when they get here....

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 03-18-2001 11:04 AM

Why don't you try disconecting the connection to automation on the Lowvoltage termianal strip and see if the manual buttons work on the dimmer
If you do that you will determin if you need a new control board or look at the automation

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