Control/Dimming LED Par malfunction

[Aedyn Raven]

Ok Update. While plugged into the three-pin non-dim (that non-dim now has a question mark on it. thanks. I'll talk to the people who installed the system about it.) manually setting a color from the face panel of the fixture works. While plugged into pure power (wall outlet) manually setting a color works. From both power sources the DMX signal gets garbled. I'm thinking this has it narrowed down to either a problem with the cables I'm using or the console. ETC Ion console and 5-pin DMX. Yes DMX, not XLR.

 

[Amiers]

The “non dim” power screwed up your PSUs. If you were running the “non dim” full at 50 then it’s not “non dim”

Noting else to blame.

 

[derekleffew]

don't go bashing my rectal scope. It's quite useful!

After all, hindsight IS 20/20, is it not?

 

[Aedyn Raven]

OK so in short, a dimmer module (even when used to produce a discrete output) clips the sine wave of the power, producing "dirty" power that is bad for some LEDs. And this dirty power can disrupt the PSU to a point that even when "clean" power is attached later it has become unable to interpret DMX signal?

 

[Amiers]

Short answer yes.

 

[microstar]

Ok Update. While plugged into the three-pin non-dim (that non-dim now has a question mark on it. thanks. I'll talk to the people who installed the system about it.) manually setting a color from the face panel of the fixture works. While plugged into pure power (wall outlet) manually setting a color works. From both power sources the DMX signal gets garbled. I'm thinking this has it narrowed down to either a problem with the cables I'm using or the console. ETC Ion console and 5-pin DMX. Yes DMX, not XLR.

So if you take take the fixture and plug it into a standard wall outlet (pure AC power, as you know) and connect it to your console with a short actual DMX cable (not mic cable, as you know) does it work properly using DMX?
If not, the DMX chip might have gotten fried by any number of mishaps. If the chip is socketed, the repair would be quite simple. If soldered in, a little harder. One of the first things to look at internally if you've eliminated all of the external causes.

 

[n1ist]

Be real careful using an oscilloscope to monitor line voltage. The ground on the scope probe is tied to AC ground and (back at the service entrance or transformer) to AC neutral. I saw this once; someone hooked up the probe, hit the power switch, and the probe's cord lit up like a lightbulb before burning through. I always use a differential probe on my scope to monitor the line, but for many measurements, a small transformer (say 120v to 6.3VAC) would work. For monitoring current, you usually use a current probe or current transformer (CT). These are isolated; they work like a clamp-on ammeter so they are safe.

As for your fixture, I agree with Microstar; sounds more like a communications issue than a power supply one. Open it up and look for the DMX line receiver. It usually is an 8-pin chip, likely 75176, MAX485, or similar. Swap it out and see if that helps.

/mike

 

[Aedyn Raven]

Plugged into a standard wall outlet with dmx straight from the console the fixture still doesn't work properly. I'll see about swapping out the DMX chip

 

[Amiers]

Sucky lesson to learn. I would say it is prolly a combination of bad power and maybe a power surge.

Rule of thumb is clean off the tap power for ML and Led Fixtures.

 

[taneglaus]

Hi, I've seen strange behavior like this before and it's been due to DMX polarity. Check the back of the console for a polarity switch. I've had people mistake it for the power switch. Are any of your DMX cables/terminators custom made? That could be another point for the polarity to get switched.

 

[Control point]

I am having some problems with some Altman Pars not listening to DMX signal, and I can't seem to figure out what is causing it. I am using Altman Cycs, Source Four Lustrs, and VL1100s as well, but none of them are showing the same issue. The pars will start strobing and changing colors seemingly at random. When I check the face panel the numbers in the ones place are cycling on their own very rapidly.
I have tried several fixes suggested by Altman and Mainstage, but none of them worked. This includes:

• Disabling RDM in the maintenance section of the Ion
• Patching the fixtures without sACN
• Terminating the DMX lines
• Running DMX directly from the board

I have also read the ESTA DMX512 standards and made sure that:

• The wattages of the fixtures do not add up to more than 1440 Watts
  
• There are not more than 32 fixtures on the DMX chain
• The power circuits are parked at 100%

Has anyone run into the same problem before? How did you fix it?

Aedan,
First, everyone is correct, find and use a constant A/C source or invest in a relay module at the dimmer rack.
The mistake you are making by setting a dimmer circuit to non - dim profile is common as venues are buying LED’s and movers and not taking care of how to get power to them.
I would probably look at the physical route of your DMX to this string of fixtures - a bunch of questions :
1- are these Altman fixtures on a “ string “ of their own ?
2- where does that string come from ? A DMX splitter ? A DMX output port from your console ?
3- are you following the DMX standard to the letter on this segment of DMX ? Cable proper? Number of units on the segment below 32? Length? Terminated at end of segment?
4- to be sure check the profile in your console patch and make sure the fixtures themselves and the profile selected in the patch are EXACTLY the same mode and profile.
Always divide and conquer when troubleshooting, fixture/power/data/ patch/ routers or splitters - isolate each.

 

[jtweigandt]

So in summary, the problem is that conventional SCR, TRIAC, or IGBT dimmers alter the sine wave of the 120v, 15A 60Hz power and many LED fixture power supplies don't like the altered sine wave. The fact that you park the dimmer at full or in relay mode does not make the AC voltage bypass the SCR's or other types of power devices which operate on the principle of chopping the AC sine wave.
ETC has come out with ThruPower dimmer modules which do allow you to change them to true non-dims by bypassing the power devices, which unless yours is a very very new installation you don't have. Hope this helps.

I have a couple of the etc true relay devices in the rack replacing dimmers. We just label the stage sockets that these are on with red tape and power all our LED from those. Since each LED device effectively frees up a dimmer circuit anyhow, giving up 4 to power 28 or more fixtures was kind of a no brainer. Using the basic relays instead of the thrupowers also assures that no JUGHEAD comes in and ruins a bunch of stuff by changing a setting. I also made up some metal flex conduit runs with multiple edison outlets for each of my over stage battons. They stay up there all the time, connected to the "LED power" circuits, so even if we are moving lights around nobody has any incentive to make/get a stage to edison to power an LED they just had to have in some position other than our standard hang. https://www.bhphotovideo.com/c/prod...fC00-lZZY_jaXvmw_qSMXEwtZLnI1PEkaAr5FEALw_wcB