Dimming LED fixtures

[JakeCTG]

Hi Guys

 

I am having a few problems with our lighting rig.

 

The parts we are having problems with are

showtech 4 channel dimmer

Par16's with LED GU10 lamp

Acme Tang02 LED disco light.

 

The problems we are having is that we have set the dimmer packs to switch mode but when we plug the LED pars or the disco light in, once the dimmer is switched on and plugged in the lighting come on very low level and the moving lighting moves slightly continuously . Once the switcher is up then the lights work fine but this means we can't switch the lights with out dimmers.

 

We have done all the basic test like testing the channel with some conventional disco lights and it works just how we want it and also checking the cables and connections.

 

This doesn't seem to make any sense to me as when it is switched right down on the switcher pack it shouldn't be sending any power to the fixture.

 

If anyone has come across this before or has any info for me I would much appreciate it.

[Brian]

This doesn't seem to make any sense to me as when it is switched right down on the switcher pack it shouldn't be sending any power to the fixture.

It shouldn't but it will.

 

Dimmer and switch packs use solid state devices to switch the mains but these devices are not a perfect switch. The presence of components meant to suppress interference will also result in the output not quite being 'OFF' when it should be. Cheaper packs do not really like driving non-resistive (ie non-filament lamp) loads and this will also make them a non-prefect switch.

 

Try running a filament lamp 'ballast' load in parallel with your GU10 fixtures. I suspect the problem will disappear. I don't know the Acme fixture you mention but I bet it'll also be sorted by a ballast.

 

 

 

[EDIT]A quick google shows the Acme to be 2x50W filament lamps not LED. Is there a different version?

[JakeCTG]

[EDIT]A quick google shows the Acme to be 2x50W filament lamps not LED. Is there a different version?

 

This is the one we have.

 

http://www.soundlightuk.com/Prolight/tango_led.htm

 

Also thanks for the response this is roughly what I thought might be happening.

[Brian]

It's probably the same problem with the ACME having looked at it.

 

The reason it happens is that LEDs and motors need very little current to work and this current can easily be supplied by a dimer or switch pack even when 'OFF'. Try a ballast and see what happens; something like a 300W PAR can would work.

[JakeCTG]

I will give it a try and let you know.

 

Thanks

[musht]

Ballast load as Brian suggests, using Multidims with LED ropelight found a 15W pygmy plugged into other IEC on the channel worked fine,LEDs dropped to zero, ran cool enough to put pygmy on a short tail and wrap the lamp in black wrap.