Never seen this before and need to figure out why

[atsugi]

I am running several scrollers and the LD needed to add more so I needed another power supply. so I hooked up the dmx to it ( power supply not yet connected to edison) and went from the out of the PSU to the in on the scroller (4 pin) It arced and got the tell tale blue puff of smoke from the power supply and the scroller. I didn't think that much power ran through DMX and 4 pin. I need to know if anyone thinks if this is human error and I done screwed up or is this something faulty with our PSU equipment. help don't want to ruin any more equipment.

 

[Brentgi]

Has any of the equipment failed due to this? I've experienced times similar to this where a PSU was not properly "drained." It's possible for some PSU's to carry residual power after they have been disconnected from power. To prevent this, it's a good idea to turn the main switch for the PSU (if it has one) to the 'ON' position with the unit unplugged from power but still plugged into the dependent fixtures.

DMX carries a minimal amount of data - max 4.5 volts, and as low as .5 volts. Also, a properly terminated DMX line would more than likely absorb any 'unused' power.

 

[theatricalmatt]

Are both PSUs from the same manufacturer? I've come to loathe four-pin because of the variety of different pin-outs and voltages that have been used in the past for it.

 

[microstar]

Has any of the equipment failed due to this? I've experienced times similar to this where a PSU was not properly "drained." It's possible for some PSU's to carry residual power after they have been disconnected from power. To prevent this, it's a good idea to turn the main switch for the PSU (if it has one) to the 'ON' position with the unit unplugged from power but still plugged into the dependent fixtures.

DMX carries a minimal amount of data - max 4.5 volts, and as low as .5 volts. Also, a properly terminated DMX line would more than likely absorb any 'unused' power.

"Residual power" likely has nothing to do with this and probably neither does the 5-pin DMX line. The 4-pin scroller cable from the power supply to the scrollers carries 24 volts DC at a few amps (dependent on current capability of the power supply) and the DMX signal.
As mentioned above, there is more than one 4-pin wiring system and if you happen to mis-match them, you can let the smoke out.
One must check the specifications carefully if you are mixing scrollers and different power supplies. Is the added power supply exactly the same as the first one? Are all the scrollers the same?

 

[Amiers]

"Residual power" likely has nothing to do with this and probably neither does the 5-pin DMX line. The 4-pin scroller cable from the power supply to the scrollers carries 24 volts DC at a few amps (dependent on current capability of the power supply) and the DMX signal.
As mentioned above, there is more than one 4-pin wiring system and if you happen to mis-match them, you can let the smoke out.
One must check the specifications carefully if you are mixing scrollers and different power supplies. Is the added power supply exactly the same as the first one? Are all the scrollers the same?

I agree but if there was no power applied to the PSU where did arc come from.

 

[atsugi]

"Residual power" likely has nothing to do with this and probably neither does the 5-pin DMX line. The 4-pin scroller cable from the power supply to the scrollers carries 24 volts DC at a few amps (dependent on current capability of the power supply) and the DMX signal.
As mentioned above, there is more than one 4-pin wiring system and if you happen to mis-match them, you can let the smoke out.
One must check the specifications carefully if you are mixing scrollers and different power supplies. Is the added power supply exactly the same as the first one? Are all the scrollers the same?

Scrollers are the Same Power supply no. So would a faulty 4 pin cable do this? Or did I accidentally

I agree but if there was no power applied to the PSU where did arc come from.

that is the question of the day my friend

 

[microstar]

I agree but if there was no power applied to the PSU where did arc come from.

That is a good question. Sounds like the system may not have been connected as illustrated. Maybe the loopback cable from the first power supply got connected to the second one and they were not compatible?? It looks like there are two loopback cables per power supply.... one from the first scroller in line and one from the last scroller.

 

[express]

[QUOTE="microstar, post: 344319, member: 18961" It looks like there are two loopback cables per power supply.... one from the first scroller in line and one from the last scroller.[/QUOTE]

I thought the same thing when I looked at it the first time.

 

[theatricalmatt]

....You shouldn't be able to connect them that way, since a scroller will have at most one input and one output. Some scroller PSUs may have more than one return, but it wouldn't be on the same output ... not certain how that might affect things, though.

OP, at the risk of setting up the same mistake again, perhaps you could re-connect the cables in the same configuration, minus the scroller flambeau, and meter the voltage coming off of the various pins of the 4-pin cable? The manufacturer should provide some information on what the proper pin-out ought to be. Once you find out what voltage is coming out of where, you should be able to isolate the problem more easily.

 

[patrickh]

I think that the system wasn't connected as described. That would be my first guess.

Also, why is there a return cable from the first scroller? I have never seen a scroller with a DMX in, DMX out, and return cable out too...which in my head makes that physically impossible.

 

[GreyWyvern]

Hi @atsugi ,

As has been mentioned, scrollers only have one input and one output, so I too am confused about the two lines going to/from the first scroller on the PSUs. Would you mind clarifying the setup? Also, are the scrollers Smart Colors or Smart Color PROs and what make and model are the PSUs?

As far as residual power in the supplies, keep in mind that they supply's output is 24VDC at 10 amps. Once powered off, even with nothing connected, they will discharge rather quickly, mainly due to the fan drawing power. Even if a unit was connected very quickly after powering it off, the unit would immediately drain the power. The likelihood of anything sparking or arcing is very small. The most likely way you would get any sparks or arcing would be if the PSU was powered, you had a return line hooked up, were plugging the male end of a cable into the female jack on the PSU or scroller, and you missed and hit the female tab and shorted pins 1 and 4 or the +VDC pin and the case.

Maybe the loopback cable from the first power supply got connected to the second one and they were not compatible??

This seems like the most likely explanation. It is never good to have two PSUs connected together via 4-pin. Check your cabling to be sure that was not the case.

If it would be easier for you to talk things through on the phone, call me. We can then post an overview of our discussion here for future reference.

 

[atsugi]

Hi @atsugi ,

As has been mentioned, scrollers only have one input and one output, so I too am confused about the two lines going to/from the first scroller on the PSUs. Would you mind clarifying the setup? Also, are the scrollers Smart Colors or Smart Color PROs and what make and model are the PSUs?

As far as residual power in the supplies, keep in mind that they supply's output is 24VDC at 10 amps. Once powered off, even with nothing connected, they will discharge rather quickly, mainly due to the fan drawing power. Even if a unit was connected very quickly after powering it off, the unit would immediately drain the power. The likelihood of anything sparking or arcing is very small. The most likely way you would get any sparks or arcing would be if the PSU was powered, you had a return line hooked up, were plugging the male end of a cable into the female jack on the PSU or scroller, and you missed and hit the female tab and shorted pins 1 and 4 or the +VDC pin and the case.

This seems like the most likely explanation. It is never good to have two PSUs connected together via 4-pin. Check your cabling to be sure that was not the case.

If it would be easier for you to talk things through on the phone, call me. We can then post an overview of our discussion here for future reference.

Figured it out, I was quite dumb in my cabling, What happened is I didn't think I rushed through things and yep had a four pin going into one power supply and the second was going out of the other. So a word of advice to all when trying to minimize the effect of adding power supplies and scrollers while an LD is cueing get everything hooked up and then ask for a few minutes to to swap things out don't rush. Luckily I just burned up one scroller and one power supply. BTW looking for a certified repair techintian for scrollers and 250w power supply

 

[GreyWyvern]

Glad you figured things out.

BTW looking for a certified repair techintian for scrollers and 250w power supply

While there are a few of our dealers that do repairs on our products, usually the product is sent back to us for repair, either from the dealer or directly from the end-user. Contact your dealer and tell them you have some units that need repaired and what the issue is. They'll tell you what you need to do.