PLuging in RGB PAR fixture casuses monitor to go blank

[BenEdwards]

Hi. I am testing a LED RGB fixture home with a ultraDMX Micro and Lightfactory. I am using a laptop with an external monitor plugged in.

When I connect the DMX cable between the ultraDMX and the fixture the external monitor goes blank. When I unplug it it comes back. This happens regardless of whether lightfactory is running.

 

I've rebooted and turned everything off and back on and still the same results.

Any ideas?

Ben

 

[timsabre]

Sounds like dodgy wiring in the LED fixture is putting a voltage on the DMX line and thence through the USB-DMX into your laptop. The earth connection on the monitor is then completing the circuit.

 

Be careful as you can easily start damaging things (including yourself) with this type of situation. You need to check out that fixture.

[BenEdwards]

Thanks, thought it was something like this.

[bigclive]

I'd suggest proceeding with caution. Many of the cheap DMX lights have appallingly poor isolation on the power supplies and there's a slight possibility that there may be mains referenced voltage on the DMX connector of your light.

 

Where did you get the light from?

 

(I kinda want to buy it off you to do some electrical tests.)

[Ynot]

If you have a DMX opto-isolator/splitter box try connecting it (carefully) through that.

If there ARE stray volts coming off the fixture, the splitter will block them and the monitor should stay kosher...

[sunray]

If you have a DMX opto-isolator/splitter box try connecting it (carefully) through that.If there ARE stray volts coming off the fixture, the splitter will block them and the monitor should stay kosher...

 

Yeah I thought that too until I tried it and discovered my opto isolated splitter used the same power source for the electronics on both side of the isolator. (See Clives video

) I intend to make changes to it one day...

[Tomo]

Condemn the LED Par until a competent person has had a chance to inspect it. Seriously.

 

If it's leaking enough to affect a monitor, it's probably Pin 1 so a splitter won't do much and the voltages may be dangerous.

I've seen quite a few cheap and nasty LED Pars playing silly buggers with Pin 1 (shield). Sometimes dangerously so!

 

Even better, send it to Clive! I'd be interested to see what's inside too :)

[dmxlights]

I have come a cross some cheep led items from china that have 5 v on pin 1 and the connector itself is ground also as in sheld ground for the DMX. I would say this is done to power some of the cheep wireless DMX devices out there.