Chineses Fixture Flikering

[vipola]

Hi, I have a Chauvet Xpress 512-Plus v106, it work great for most of my light..

but I have some issue with my LEDFX-20 (http://novamarketing.ecwid.com/product?8003741), yes I know, cheap chineses fixtures, they fliker really fast, just like if the signal sent was X-0-X-0-X (X been the programmed value and 0 been a 0 value), they react very well with my hardware dmx controller (obey-40 like).

I tought upgrading from v105 to v106 would fix the issue, but without sucess.. :/

I also tried to unplug the DMX cable from the Xpress512 in the middle of the usage (while it's sending a color signal to the fixture so the lamp is on (flashing), if I unplug the cable it will suddenly stop flashing.. depending on the timing.. sometime it will stay OFF, other tiem it will stay ON (without flashing).. so it's really like the DMX Controller is sending a some 0-value between..

If i use a X/Y Channel, it will do the trip to the right place, and then go back to 0 position, and then go back to the place.. and do it back and forth..
they react that way because they are cheap fixture and when you give a position it will ignore all new command until it reach that position, that's why they will go up to the full programmed position before going back to 0 instead of going back to 0 before reaching the dmx..

I searched everywhere in the software for a 'clock' or 'refresh rate' but i didn't found anything..

Also If I upload a scene to the interface and run it out of the software I have the same issue..

Maybe would there be a DMX Filter that could smoothen the signal or something?..

Any ideas welcome

Thanks

[dkumpula]

I've experimented with many different fixtures over the years, but have never seen a device that ignored other DMX commands until it reached a desired XY position. Are you sure it isn't just a symptom of a bad DMX board in the device?

I have seen several cheap devices over the years that do not respond reliably to DMX signals like you describe, but the problem has been one of the following:

• 1. A defective DMX board in the unit
  2. A bad DMX cable connection in the unit
  3. A poor signal level at the device due to a defective or over absorbing unit further up in the serial chain or a bad cable or too long a cable run

In the case of #3, I leave the over signal absorbing unit as the last in the chain after checking the cable, of course. I also use optical DMX repeaters to ensure a good signal to all devices.

After experience with poorly designed and constructed devices without support or high shipping costs, i eventually decided it was less problematic to buy from in-country suppliers with a good reputation.

David

[vipola]

Thanks for your ideas and feedback..

Actually I have 3 of theses devices from two different batch and that's how they were reacting to my Hardware DMX controller also, tried many dmx cable many lenght and even that as the only device plugged in.. so I think they are really poorly designed that way.. They also say it's 8 channel but I never found what channel 1,6,7,8 were for.. (2,3,4,5 are for X/Y/Color/Strobing).

They will order to one command at the time, if it's to light in red, move, light in blue, it will wait that the move is completed before switching to blue, whatever time that take.. it's very not friendly to program anything with them so most of the time I simply set them at one position for the whole scene and just play with the color and the on/off..

But because of that strobing dmx glitch (witch is not related to wating one command before doing another one), I can't have them steady on, they are always strobbing and I can't position the X/Y because they always travel back and forth between 0/0 and the desired position.. so they are pretty much unusable with my Chauvet Xpress 512-Plus (but they were okay with the Chauvet Obay 40)

It's a Chinese fixture but they are sold in some dj retail store over here because they are very low cost (under 100$), at the time I bought them I wasn't into DMX and those stuff, so I din't really noticed that particularity and I would'nt really care. I am now replacing them for some Martin MiniMac Profile.. but since I already have them I try to make them work..
All I try is to have a steady dmx signal to the unit, not flickering signal..

But I agree with you that now that I play with DMX I really appreciate and aquire quality fixture, they also offer way more DMX Command, and most of the time you can trigger some pre-programmed template instead of coding everything from scratch.

What I find strange is if it was just something about a signal beeing to quick or something the fixture would always react the same way when I unplug the dmx cable.. but now sometime they get the 0value and just stay dark and sometime they get the desired value and stay at their x/y/color position.. was the signal sent by the Chauvet Xpress512-plus ever been watch trought a osilloscope and compared to a hardware dmx controller like the chauvet obey 40?..

Thanks

[dkumpula]

What I find strange is if it was just something about a signal beeing to quick or something the fixture would always react the same way when I unplug the dmx cable.. but now sometime they get the 0value and just stay dark and sometime they get the desired value and stay at their x/y/color position.. was the signal sent by the Chauvet Xpress512-plus ever been watch trought a osilloscope and compared to a hardware dmx controller like the chauvet obey 40?..

Hi Vipola,

Yes, it looks like you've tried everything you could and it is simply a poorly designed fixture. As far as unplugging the cable goes and having it "remember" the last value, I've seen this on simple RGB LED controllers (the type used for under cabinet or building facade lighting). Those also act pretty funky, but they aren't designed for fast DMX response or playing nice with other devices.

Sorry I don't have a better suggestion than to do what you are already doing - buying something more upscale. I suspect eBay is your friend for unloading these devices to someone that simply wants to leave them in auto mode.

Warm Regards,

-David

[vipola]

Thanks for your reply, it's nice to see that someone take the time to read and think to this issue..

what I don't understand is, if it was something about fast signal DMX, it would always send the same signal, so when I would unplug it it would always act the same way, not sometime on and sometime off.. right ?..

[dkumpula]

Hey Vipola,

Sure, happy to help where I can!

What I intended to say is that the unit's DMX board apparently has two problems. The first is that it only does one thing at a time. Personally, I think this is almost comical that someone designed it so poorly. A half second of thinking should have told the engineer that this was a dumb idea. I can only guess that they tried to adapt existing / cheap parts not up to the task of moving a DMX head. However, I don't think that this would account for the intermittent on/off behavior you see when you unplug the DMX cable from the unit.

The second being the flickering issue, meaning that it needs an unusually strong DMX input signals or that the internal DMX board processing is so slow, that it can't even keep the unit stable when receiving an adequate DMX input signal. I have seen the unusually strong DMX signal thing once on one of several RGB moving heads from China. After going through the trouble of shipping the bad unit back to China at my expense and having the retailer swear that it worked great on their end and then return it in the same condition, I stopped buying cheap moving heads from China based retailers. Personally, I'd bet that the signal level issue due to a bad board design or possibly an inadequate power supply. If you open it and see an unregulated power supply /transformer inside directly attached to the DMX board, I'd bet a nickle this is your problem as Chinese retailers are notorious for putting in really cheap power supplies. If you find this, you can try replacing the transformer with a switching power supply of equal or greater amperage (and matching voltage, of course) to see if this does the job. Not sure it is worth your time depending on what you paid for the unit. The cost of a decent switching power supply is likely in the US$20-$50 range.

I suppose it could also be a faulty ShowXpress DMX controller, but the lack of issues seen on this website over the years with the Chauvet products, I would bet against that unless you see it with several other DMX devices.

Regardless of what is causing the problem, the inconsistent behavior you see when you unplug the cable is probably just whatever signal it had for that millisecond when you unplugged it. (Note that it could be flickering more than you can actually see thanks to capacitors compensating or really fast blinks that you can't detect visually.) As I mentioned, I have seen this behavior on some LED strip DMX drivers, but I think it is intentional in this case as you may wish to only hook up a DMX signal to a building or cabinet lighting input occasionally to change the color / brightness - otherwise it does whatever it was doing before whenever you apply power with no DMX signal. This works the same way on the cheap led screw in lights that come with a remote control - so it may not be far fetched to think that they tried to adapt such a device for use in a moving flood.

Good luck!