URGENT: Apollo Smart Power - DMX signal dropouts

[greatdebate]

We have two of the 450 watt (not sure on exact wattage, but one of the first gen versions) Apollo Smart Power supplies that handles up to 12 scrollers. During rehearsal last night, we noticed that one of the power supply units stopped receiving DMX (scrollers stopped responding and the DMX signal LED was dead). We checked the connections (DMX, power) and all was well. We have a Rosco fog machine and second power supply that have feeds from the same opto-DMX splitter, and those operated fine throughout.

Upon unplugging the power from the constant power source and then plugging the power supply back in re-discovered the DMX signal. It would work fine for approximately 20-30 minutes before the same issue occurred.

The musical opens this Thursday, so I'm giving myself today to try and troubleshoot any issues. If it's still not resolved by tomorrow's final dress, I'd probably order a new power supply and have it one-day shipped to have it by Thursday.

Thanks!

 

[TheaterEd]

I've never worked with this unit before so this is just an idea.

Looking at apollo's website, they say that a color scroller uses 38 watts. If you are using 12, then you are over your 450 (although they currently only sell 400 watt supplies). Is it possible that you are just over loading it, and dropping the DMX signal is its way of protecting itself? You might try powering it up and not actually running the scrollers to see if the problem still occurs.

That or I am way off base and someone from Apollo will be by shortly to lend their expertise. Either way, good luck.

 

[sdauditorium]

Good idea. According to the specs, it's supposed to handle 12 scrollers on a 400-watt supply. However, I do have a 75w supply that I will plug four of the scrollers into to see if that does help. Another thought was to switch the two 400-watt supplies to take the other's load of scrollers to see if the issue appeared in the other scroller. That would seem to lend credence to your idea.

 

[Kelite]

It does sound as though more Wattage is needed than the current PSU supplies are rated for. Placing 4 x 38W scrollers on a single 75W PSU doesn't seem to solve the problem...

 

[sdauditorium]

It does sound as though more Wattage is needed than the current PSU supplies are rated for. Placing 4 x 38W scrollers on a single 75W PSU doesn't seem to solve the problem...

Are you saying that taking a few scrollers off that problem supply unit to reduce the load and moving them onto another (different) power supply wouldn't reduce the overload? Sorry, I'm a bit confused reading the reply. Thanks Kelite!

 

[sk8rsdad]

Are you saying that taking a few scrollers off that problem supply unit to reduce the load and moving them onto another (different) power supply wouldn't reduce the overload? Sorry, I'm a bit confused reading the reply. Thanks Kelite!

I think what Kelite is suggesting is that moving 4x38W (152W total) to a single 75W supply is going to overload the 75W supply.

 

[sdauditorium]

Correction: I just referenced our Tech Specs and the third PSU that we have is actually 150 watts. Not being able to be in the facility until this afternoon, I was trying to shoot from memory which is apparently shot from the last two weeks of late-night rehearsals.

Is it possible this overload would cause the PSU to stop receiving the DMX signal?

 

[Wood4321]

Correction: I just referenced our Tech Specs and the third PSU that we have is actually 150 watts. Not being able to be in the facility until this afternoon, I was trying to shoot from memory which is apparently shot from the last two weeks of late-night rehearsals.

Is it possible this overload would cause the PSU to stop receiving the DMX signal?

It shouldn't cause it to stop receiving signal, but I would think it could make the power supply shut off. This would cause the DMX light to turn off, until power was cycled to the unit. The unit would technically still be receiving signal, but without power it wouldn't be able to show you.

 

[sdauditorium]

Thanks for the reply. The red power LED was still lit but maybe that was just due to whatever residual power was left in the PSU?

 

[Kelite]

I apologize for the lack of response on my part, keeping active within lighting forums is beneficial but I have other opportunities demanding my attention too. My apologies!

As sk8ersdad commented accurately, the shifting of scrollers from an overburdened PSU to another power supply will likely solve the power problem. If the second PSU is overburdened, it too will face the same symptoms as the original PSU.

IIRC, an overloaded PSU will cause some of the scrollers (or all,depending upon available 24VDC power) to 'drop out' of the cycle. I don't recall this causing a PSU to turn off or not receive DMX data from the console however...

 

[hobbsies]

Correction: I just referenced our Tech Specs and the third PSU that we have is actually 150 watts. Not being able to be in the facility until this afternoon, I was trying to shoot from memory which is apparently shot from the last two weeks of late-night rehearsals.

Is it possible this overload would cause the PSU to stop receiving the DMX signal?

There's also cable resistance to take into account. You could probably only reliably get one 38W scroller onto one 75W PSU. I had this same issue with Apollo scrollers. They use a lot of power. For a 150 W PSU, you could get three scrollers (114W + 15ish watts for cable resistance).

 

[sdauditorium]

Thanks for the suggestions. I do have the 2nd 400-watt PSU connected to the first via the DMX pass-through. Could this be an issue as well? If so, it'd be easy enough to run a separate line from the opto-splitter to the other PSU.

 

[FMEng]

You should not daisy chain power supplies together. They will not equally share the load. Whichever one is slightly higher in output voltage will do all the work. If the system is loaded beyond 400 Watts, the "leader" supply will overheat, then the second one will overheat after the first one shuts down. Separate the system into two.

It is possible to design supplies to allow them to be combined for redundancy, but it is unlikely be the case here. Even if they were, the redundancy would not increase the load capability.

 

[sdauditorium]

You should not daisy chain power supplies together. They will not equally share the load. Whichever one is slightly higher in output voltage will do all the work. If the system is loaded beyond 400 Watts, the "leader" supply will overheat, then the second one will overheat after the first one shuts down. Separate the system into two.

It is possible to design supplies to allow them to be combined for redundancy, but it is unlikely be the case here. Even if they were, the redundancy would not increase the load capability.

That sounds like that might do the trick. I hadn't thought about the daisychaining issue with power supplies. I will run another DMX line from the splitter to the other PSU and give an update later.

 

[PeteEngel]

There should be no issue with DMX passing through one PSU to another for control. The DMX signal to the PSU isn't load dependent so the daisychain is just like passing DMX through any other fixtures or products. There should not be any "load" involved with this segment of the control system. Does the PSU self terminate or is there a terminator on that DMX line? You may just have a failing DMX card/component. Also, another idea would be since this is an older system, could you have a failing scroller that is drawing down the PSU?

 

[Kelite]

Pete is correct. As long as the 5 pin DMX line is passing through one PSU to another, load has no affect on the DMX side. Daisy chaining PSUs together via the 4 pin scroller cable is certainly a no-no, as mentioned by FMEng.

 

[sdauditorium]

Good news. I pulled out the 150 watt PSU we had and threw a couple of scrollers on it. I also ran another DMX line from the splitter and re-configure the loads for each 400-watt PSU. Everything worked great for the last rehearsal plus programming changes (5-6 hours), so I'm confident we're golden. Thanks again to all who had suggestions. We absolutely couldn't be happier with the Apollo products we have (24 scrollers, PSUs, 2 Right Arms).

 

[Kelite]

Thanks to all the ControlBooth members who care enough to help troubleshoot systems. Kudos to you guys!

 

[LD4Life]

One other thing to keep in mind for future reference since you were mentioning DMX dropping out, is that each run of scrollers can't be longer than 200' and must loop back to the Smart Power in order to get consistent DMX signal. I've had that issue in the past, and it caused very similar issues to what you were having.