Forums > MaxMSP

DMX USB PRO and LED light array / random flickering

March 31, 2007 | 5:24 am

Dear List:

I know this is probably a bit off topic, but i learned about this device on this list, and I am desperate. (Installation opens monday). I am running the USB-DMX-Pro on OSX in max-msp. I have installed firmware 1.43 and latest VCP driver from http://www.ftdichip.com/.
It is working fine for controlling my standard dimmerbox via 5-pin to 3-pin convertor (wired 1-1, 2-2, 3-3, but when controlling these LED lights I get random flickering. They use 4 dmx channels. (brightness, R,G,B). Those all are responding as expected except for the flickering.

If I quit max and just allow the usb dmx pro to continue updating the lights the same thing occurs, so I know the problem isn’t with max.

Anyone else have experience like this with this unit or DMX-LED light arrays? (I am not sure what the brand is of the lights, they are rentals and it isn’t written on the unit) I know the light isn’t broke because this happens on all of the units. (12) I’ve tried all different refresh rates, baudrates, with a terminator, etc.

Thanks,
Christopher Overstreet


March 31, 2007 | 10:01 am

hi christopher,

i’m not sure if i’m telling you anything useful, but the words DMX and LED just triggered a memory of an experience i had with a LED(array) lamp 2 weeks ago.
i connected the lamp to a dimmer (assigned as non-dimmable, so either on or off) to control it via midi.
with the first dimmer i used it seemed to work, but on the second, the lamp wouldn’t go off – even with the mainfader at 0.
it appeared that also a "ballast" lamp had to be connected, to give the dimmer the load that it needed to realize that actually something was connected.
so maybe just try to connect an incadescent lamp on the same channel & see if that makes a change..

good luck,

jan klug


March 31, 2007 | 11:59 pm

Thanks Jan,
But these lights have their DMX built in, so it is unrelated. I did try addressing my other dimmerpack to the same channels, though just in case but it didn’t help.

So far from other resources I have been hearing "Are they truely DMX compliant?" Turns out there are two types of compliancy, true and untrue. Seems these lights can’t keep up with the output of theatre quality dmx. They only work with rock and roll and night-club boards. Seems a bit weird to me.

I was thinking of trying some of those "cheap" LED DMX Tubes, but might have the same problem.

Christopher

Quote: Jan Klug wrote on Sat, 31 March 2007 03:01
—————————————————-
> hi christopher,
>
> i’m not sure if i’m telling you anything useful, but the words DMX and LED just triggered a memory of an experience i had with a LED(array) lamp 2 weeks ago.
> i connected the lamp to a dimmer (assigned as non-dimmable, so either on or off) to control it via midi.
> with the first dimmer i used it seemed to work, but on the second, the lamp wouldn’t go off – even with the mainfader at 0.
> it appeared that also a "ballast" lamp had to be connected, to give the dimmer the load that it needed to realize that actually something was connected.
> so maybe just try to connect an incadescent lamp on the same channel & see if that makes a change..
>
> good luck,
>
> jan klug
—————————————————-


April 1, 2007 | 9:05 am


April 5, 2007 | 7:37 pm

I am seeing the EXACT same thing.

I’m using Weidamark DMX PAR 64 LED lights.
I’m also using Chauvet LED BAR Colorbar panel ( 4 section panel).

When using FreeStyler with Enttec DMX USB PRO, any LED short of full brightness setting flickers. The dimmer the setting, the worst the flicker.

Yes, I have terminated and verified the load resistance using a meter.

Now, if I connect the DMX line to my old AMDJ Operator 192 controller, there is some flicker but not bad.

This appears to be an issue with the Enttec DMX USB PRO.
I see in the documentation the the refresh rate is user sdjutable, but I see NOTHING anywhere on how to do this?

I’ve tried only using the Weidamarks and the Chusvet LED by themselves and it still exibits the same proble using the FreeStyler to Enttec DMX USB PRO.

Any help on this? I’m going nut here…
Thanks, Steve


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