Control/Dimming LED DMX Anomolies HELP PLEASE

[JD]

One other thing to throw into the pot- Could be a faulty fixture earlier in the chain loading the DMX down even though the fixture itself is working fine. Might want to plug everything together and then pull the connector at the board end. Take a multimeter and read ohms between pins 2 and 3 on the line feeding the lights. Should be somewhere around 120 ohms. May not be, but should not be lower then 80. Then read between pins 1 and 2, and again between pins 1 and 3. Both should be fairly high. If one of those reads real low (less than 50 ohms) you have a short. Start eliminating lights and cables and when you pull the bad one, the reading will change radically.

 

[MNBallet]

In picture 4, the DMX cables just don't look right. I'm seeing some kind of funky wave design down the cable. Is that right? Do these fixtures have DMX tails that are hard wired in, or are they DMX jumpers that you plug in?

I also remember reading that your DMX cables are Hosea brand? I once bought a bunch of DMX termintators from them and as soon as I plugged one it all my DMX toys went BONKERS! I tried several different terminators from them but each one sent my toys in a tailspin. I switched out to a different brand and they all behaved.

If your event is now over, I would put all your lights out in your shop or what ever. Plug your board into the very first one. How many lights turn on, just the 7? Then skip the first one and plug directly from the board into the second one. Did the 7 lights move down the line? Then plug directly into the 3rd, did the 7 move again? If this is the case, then it's either your cables not being up to standard, the units themselves not being a good "thru"....

Oh, just thought of something. Are you running all your units on the same DMX address, or just the first as a "Master" and all the rest as a "Slave" unit?
There might be a limitation on how many "slave" units a "master unit" can controll. If that were the case the rest of your lights would be looking to the first light for the output signal and not your lightboard.

Kenneth Pogin
Production / Tour Manager
Minnesota Ballet

 

[kendal69]

JD -

God one. So since this same strangeness has happened on the last three gigs what might be happening is there is one bad apple in the bunch causing the other to go bonkers. Hmmmmmmmm. I plugged in two lights and tested the ohms and one pin had over 300 ohms and the other pin had 70 ohms?? Both lights and had nearly the same readings?? Love the light hopping technique. Where the heck do come up with this stuff, dude, your a Master.

MN Ballet,
YA those strange tails are hard wired in. They are the DMX in and out, also a daisy chain power tail in from instrument to instrument and finally a traditional edison plug tail. What a spaghetti mix.

OK I'll order some new terminators and check on that one.

I have done the salve master with these lights the first day I got them and had the problem again with the last few lights do not cooperate. When I did it with the board with NO SLAVE I got the same results. All is fine to a point then the last few lights fail to work as the others.

Hey Ken, my wife's from Minnesota up on the Iron range - She's a RANGER, OOFTA

 

[Rob]

Something we've seen with low end LED fixtures (and not only cheap Chinese knock-offs) are poor quality transceiver chips. If your console allows it, try slowing the DMX output speed down as much as possible.

But, as other posters have mentioned, what you're describing sounds like incorrect termination or a cabling issue.

Robert Armstrong
Pathway Connectivity

 

[JD]

Although the 70/300 reading sounds like a smoking gun, it may not be. Many devices use input gate protection. You may find that you read say, 70 ohms from pin one to pin two, but if you flip the lines (red and black) on your multimeter it jumps to 300 on the same set of pins. (or visa versa) Still, if it doesn't change, there may be a problem. If all the lights read that way then it may be a design idiosyncrasy. Unfortunately, you may not be reading ohms if there is gate protection as what you are actually reading is the 0.5 volt drop across the protection diode.

 

[dramatech]

I am pretty sure that you have checked this, but on lesser expensive and many chinese products, there are 10 switches in the address dip switch. It only requires 9 to do a full DMX 512 address. The tenth switch is used for several functions by different manufactures, such as master/slave selection, non-DMX operation, sound activation and in many cases, termination. If you have a 10th switch, check and make sure that it isn't a terminator and that you not are multi-terminating.

 

[MNBallet]

I am pretty sure that you have checked this, but on lesser expensive and many chinese products, there are 10 switches in the address dip switch. It only requires 9 to do a full DMX 512 address. The tenth switch is used for several functions by different manufactures, such as master/slave selection, non-DMX operation, sound activation and in many cases, termination. If you have a 10th switch, check and make sure that it isn't a terminator and that you not are multi-terminating.

in the pictures he posted, these units are led screen in the back, no dip switches.

 

[kendal69]

dramatech,
No dip switches, everything is done via those digital numbers you see on the back of the light.

1 = MAster dimmer
2 = Red Color
3 = Green Color
4 = Blue Color
5 = White Color
6 = Syrobe Effect Adjust slow to fast
7 = Preset Program Black out 000-127, fade program 128 - 255 Use 6 to adjust speed
8 = Preset Programs Black out 000-127, Color Chase 128-191 Use 6 to adjust speed
9 = Macro of colors

pathsupport..........

WOW I stopped at your site, looks like I will be spending some monet with you.

Looks like your on the same page as Fleenor.

I spent some time on the Phone today with techs at Doug Fleenor and they suggested I get a:
The DMX2DMX addresses issues associated with non-compliant DMX devices. Many lighting devices claim to accept DMX512 signals, but are unable to support the wide variety of timing parameters allowed by the DMX512 standard. The result is flickering, flashing, or erratic operation. The DMX regenerator addresses these issues by receiving any DMX512 signal, buffering the data, and then re-transmitting the data under a well-defined set of timing rules. In addition to this, the input is fully opto-isolated to provide protection and to break potential ground loops.

It will come tomorrow. looks like others are having huge problems with non compliant lights like Chauvet. They say this will slow down the signal.

New terminators on the way also from Fleenor.

 

[kendal69]

OK here's what I did yesterday.

I layed out 8 lights ( last time I had problems at light 5 and could not get the last three to work ) so I strung out the lights and use 50' of the worst DMX and a mix of DMX and mic cable and NO TERMINATOR to force a problem. Sure enough even though all lights had power and all lights were addressed correctly I had one light that would not work. I connected the The DMX2DMX box and WHAM it corrected the light and it started working.

I disconnected the The DMX2DMX box and it continued to work after leaving the lights on and playing with them for an hour.

I will test next time with 24 lights and see what happens.