Film-Tech Forum ARCHIVE: CNA-100 Problem: Lights Come On Sporadically During Show

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Posted by Shane Hoffmann (Member # 1620) on 05-19-2007, 01:52 PM:

For the past few months, the lights in one of our auditoriums have come up all the way at random points during shows. It has become much more frequent in the last week. We are running a CNA-100 Automation with a Lindsey Fairbanks Dimmer on the house.

The lights come up to full brightness every time, but the automation panel still says that they are down. Pushing the "Down" button does make them go back down.

I spoke with an engineer at Eprad earlier this week who told me to find a service bulletin on Strong's website about eratic behavior. He was pretty confident that would take care of it(it involved soldering new capacitors on each termination board). So I did that, but it didn't help.

I'm not sure if it is necessarily the automation; perhaps it's something in the dimmer. Has anyone ever had this problem before?

Posted by Chad M Calpito (Member # 3736) on 05-19-2007, 03:35 PM:

I use the same automation system & Light Dimmers for projectors #1 & #10, but, never encountered the problem you are experiencing. Unfortunately, I don't have any suggestions to give you.

Posted by Jeremy Weigel (Member # 4208) on 05-19-2007, 08:02 PM:

Can you disconnect the automation inputs to the dimmer and manually dim at the dimmer? If you can, I would try that first to see if it is errant signal from the automation. If the lights come up without the automation connected then your dimmer is the culprit.

Posted by Monte L Fullmer (Member # 2797) on 05-19-2007, 11:56 PM:

How are your CNA's programmed? Sounds like an extra cue is being left on the print (if youre a discount, or 2nd run house..) and throwing off the programmed sequence - meaning that this extra cue is telling the CNA that it needs togo into "credit" mode.

There is a procedure in programming CNA's so the start/run/credit/end of show sequence are in proper operation conditions..

(I deal with 8 of these CNA-100's and have to ensure that their programming is correct ... and don't ever mess with that CUE FAULT (grey button) button..for that shuts down the failsafe devices on your console setup.)

If you (or anyone) needs help on programming CNA's, holler at me via email and I can give you the programming instructions...

Posted by Shane Hoffmann (Member # 1620) on 05-20-2007, 04:16 PM:

We do mostly first-runs, and the entire display panel looks as it should during the show--the right cue number, the lights "down" button lit, etc. Also, it has happened several times during the same show. So I don't think it's the cues.

Last night I disconnected the automation from the dimmer (a luminary 6-4), and it still happened. So I'm now looking primarily at that dimmer box for my problem. We swapped the cards for the house and stage, but the problem did not follow it. (It's only the house lights that turn on).

The last thing I did was switch the SCR-1 and SCR-2 chips; I wanted to see if the stage lights would come up instead so that I could blame that chip. So far, though, the lights have not come up today.

Posted by Mike Olpin (Member # 1115) on 05-20-2007, 06:57 PM:

I had a similar problem. What do the LEDs on the dimmer indicate? There are two LEDs for Stage, and three fo house. When our dimmer was wigging out, the LEDs would also act eraticaly. The lights would dim fully, but the LEDs would stay at preview levels (red and green) then when the dimmer randomly decided to bring up the both sets of lighting, the LEDs would jump to yellow and red. In our case the solution was to replace the dimmer as a whole.

Posted by Monte L Fullmer (Member # 2797) on 05-20-2007, 06:58 PM:

Okey -- what was the previous film in that house like - did this problem occur with that print, or did it just begin with this print? (have to 'condemn' as much as possible here...)

I've had small issues with Luminary 6-4's with that SCR chip issue before, but luckilly,we only used the one channel making the 2nd chip as a spare.

When the lights pop on, what is the display on the CNA reading in the houselight area?

Another thing one must be aware of is that the display panel on these units will short out when they want to, for I've relaced two panels already due to fouled operations...and a simple test is to swap out panels with another CNA unit - this is how I found out my problems with the two panels mentioned above.

Just some more help and tips for you. - Monte

Posted by Ken Lackner (Member # 1002) on 05-21-2007, 08:04 AM:

quote: Monte L Fullmer
How are your CNA's programmed? Sounds like an extra cue is being left on the print....

quote: Monte L Fullmer
What was the previous film in that house like - did this problem occur with that print, or did it just begin with this print?

quote: Monte L Fullmer
When the lights pop on, what is the display on the CNA reading in the houselight area?

quote:
The lights come up to full brightness every time, but the automation panel still says that they are down.

quote:
Last night I disconnected the automation from the dimmer (a luminary 6-4), and it still happened.

Call me crazy, but I think we can rule out the CNA as the cause of the problem here. I have had a lot of issues with those LFI dimmers doing weird random things. My suggestion was going to be to swap the SCR, and I see you have already done that. Your last post said that so far the problem has not occured again. Is this still the case? If not and you are still experiencing the problem, the main board in the dimmer may need to be placed.