CTB16PC one channel stuck on about 50%

[bhays]

I have one channel that stayed on tonight after the show completed at about 50% intensity. Sporadically, the channel will turn off and come immediately back on. This happened about a week ago with the same channel, but a reboot of the show computer cleared it up until tonight.

I have:

1. Removed and Reapplied power
2. Performed a controller reset via the jumper on 2nd row of pins
3. Killed power to entire network of controllers and reapplied power
4. Rebooted show computer
5. Disconnected Cat5 from entire network
6. Reloaded Firmware and did clear standalone
7. Rebooted show computer

When I use the hardware utility or a sequence, the channel will fade up and down, shimmer, twinkle, you name it, just not below about 50%...

I thought a blown triac was just on all the time and wouldn't do anything else. Any ideas? I have a spare channel on another controller to move those lights over to, but wanted to try any other options first.

[-klb-]

It sounds like you have a really odd failure of of the triac. A triac is fairly similar to a pair of SCRs facing opposite directions, with the gates tied together. This is because a SCR can only conduct in one direction, so it takes two of them to conduct in both directions. Intrinsically, only the one facing the right way will conduct when triggered. If one of the two were to fail in a way that it always trigger on its half cycle, you would always get a minimum of half intensity, then as the phase angle where the other half of the triac fires is controlled by the controller, you will get the various effects played out from 50% to 100%.

So, yes, I think you have a failed triac, or possibly a failed opto isolator, since it is essentially an optically triggered triac.

[bhays]

-klb- wrote:

It sounds like you have a really odd failure of of the triac. A triac is fairly similar to a pair of SCRs facing opposite directions, with the gates tied together. This is because a SCR can only conduct in one direction, so it takes two of them to conduct in both directions. Intrinsically, only the one facing the right way will conduct when triggered. If one of the two were to fail in a way that it always trigger on its half cycle, you would always get a minimum of half intensity, then as the phase angle where the other half of the triac fires is controlled by the controller, you will get the various effects played out from 50% to 100%.

So, yes, I think you have a failed triac, or possibly a failed opto isolator, since it is essentially an optically triggered triac.

Still strange that they flicker and go completely out intermittently, though.

Ok, I will switch out the channel before the show tonight and plan on sending that controller in for repair after the season. First failure in three years on 17 controllers, so can't complain.

[bhays]

Ok,

Here's an update. I left that controller plugged in overnight ,got up, channel still on 50%. Unplugged it. Got home from work, plugged it back in. Same channel came back on, then turned off. Now just used console and was able to fade channel up and down, no problem, etc. Working fine.

Show starts in ten minutes, we'll see if it does fine and if it stays on when the show ends tonight.

Bizarre!

Brett

[bhays]

And tonight at the end of the show it shut off normally.... this is beyond strange.

[Max-Paul]

Go and get the Father down at the local parish. That box is just plain old haunted.

Glad to hear that it is now working.

[bhays]

I believe an exorcism may be in order, lol. When I came home today the same channel was on and slowly fading all the way off and back on. I have triple verified there is no standalone sequence on the box.

When the show started, the channel turned off and is currently working fine.... strange stuff.

[fair28]

I had the exact same problem (strange) with the exact results (the problem went away on it's own in time). I have 8 controllers and this is the first time I've had any issues. I may send it off to Dan after the season is completely over to see if all is ok. I'm glad in both cases the problem seemed to have resolved itself.

Take care all and Happy New Year!

[Bryan]

I had the same problem this year with my new CTB16PC. One channel stuck on about 50% and would not shut off at all, but would do shake/ shimmer and all the rest of the stuff above 50%. I did the reset and nothing changed, I had another channel open so I moved everything to it. Now 2 nights ago I had another channel on the same control do it again . I unplugged the lights on that channel and have not looked at it again. Once I get it all down I am going to hook that controller up and see if it is working right if not I will ship back for repair.

Any input would be great!! I will post my findings when I test the controller.

[Gary Levelius]

Check for moisture on the PC board and use a hair dryer to dry it off if you find any. Failing that, change the optocoupler (the 8 pin IC, usually white) associted with that triac. If you know the channel but not sure which opto to change, give the support guys a ring. They can tell you which one and send you the parts if you're comfortable unsoldering and soldering PC boards. I had a CTB16D controller with the same problem this past summer and the opto solved it. Might want to have them send a triac as well, just in case that might be it if the opto doesn't solve it.

-Gary-

[Brad Stucky]

Bryan wrote:

I had the same problem this year with my new CTB16PC. One channel stuck on about 50% and would not shut off at all, but would do shake/ shimmer and all the rest of the stuff above 50%. I did the reset and nothing changed, I had another channel open so I moved everything to it. Now 2 nights ago I had another channel on the same control do it again . I unplugged the lights on that channel and have not looked at it again. Once I get it all down I am going to hook that controller up and see if it is working right if not I will ship back for repair.

Any input would be great!! I will post my findings when I test the controller.

Hey Bryan, have you had a chance to test your controller or find out anything about it? I, too, had the same problem with one of my new CTB16PC boards. One channel is stuck on at 50% but would still function with events above that level. Another one of my boards (also a new CTB16PC) also had the same problem, but when I was checking it with an incandescent load of about 15 watts (instead of my normal 50ct. LED string) after about 20-30 seconds, the light suddenly went out. When I connected a data input and loaded the hardware utility, it functioned correctly. I can't get it to malfunction, now. Both of these boards have/had their problems with channel 8. This is my first year of any board malfunctions after 3 previous years with zero problems on 15 other controllers. Anyhow, I just thought I would add my two cents here since I had the exact same problem.

[bhays]

I can't seem to get it to repeat now either. I may send it in to be checked just to be safe.

[t.vanhouts]

bhays schreef:

I can't seem to get it to repeat now either. I may send it in to be checked just to be safe.

That's odd. Normaly a load on the mailfunction channel is just enough to close the gate of the triac. When that doesn't work anymore its look like the triac wouldn't close properly. Get the power of your controller for a few minutes so that capacitors are empty and try to put a load on the channel and Plug in your controller to try again. that sometimes will work. (with the load of course)

When this gives you no result than is deeper in your controller. Leave it then to the experts.

[Frank Picozzi]

I had this same problem, it happened at night long after the show was over. We had a torrential rain and wind storm. When I woke up the next morning I noticed that I had two channels on at fifty percent. I ran a sequence and everything worked including those two channels except that they wouldn't shut off all the way. I suspected moisture. I opened the box and used a hair dryer on it for about 5 minutes and the problem went away and didn't return.

[stanward]

I think it is imperative that you conformal coat both sides of the boards before final assembly, especially if those controllers will be subject to high humidity.

[t.vanhouts]

stanward schreef:

I think it is imperative that you conformal coat both sides of the boards before final assembly, especially if those controllers will be subject to high humidity.

I think that coating the board after assembly will keep the board better protected from weather influence. In this case you can be sure that also the soldering is coated and even all leeds to the components on the board. You have to be sure that all your soldering is done properly. Many failures have to do with bat soldering. And it's hard to replace a component when the board is coated.

But beside that I have to say that the humidity in the Netherlands is about 75 to 85% these days. I use the Light-O-rama encloser and a bucket with a lit for my controllers. After I had build the boards the the board works fine. After a few days I discovered some intensity problems. (Stay on at 50% no shutting down and so on. I put a snubber in every CTB16PC channel and after a few hours turn back the power and running the show everything worked fine. The boerds are always outdoors even with heavy rain and snow. Problems? NO.

I think for next year to be secured from possible humidity I gonna coat all my boards. It's a very good tip.

To see how my boards are placed in my enclosures look at my website on the page foto's. They are not coated at this time. I am sorry but the website is in dutch language.

[RiscIt]

We had this issue before Christmas on a CTB16PC card I built an enclosure for.

I discovered it while going through and labeling each distribution cord. Channel 7 was stuck on at ~50%, and it was like that the instant it was plugged in, but behaved as expected otherwise (responded to all commands except off and could not dim below 50%)

In troubleshooting I move the cord I had on channel 7 to channel 6 and vice versa... Which took care of it. Since the cord set worked fine on the other channel (and the cord from ch 6 worked fine on 7), I can only assume it was the act of re-seating the spade connector which fixed things.

...So if anyone else is in a similar situation, you might try that.

It worked fine all season