Dimmable LED Downlights that will not dim...advice please

[Dave Jenkins]

Now, over the years, I've fitted loads of LED downlights - 100s if not 1000s by now - just like you guys/gals probably. They always work, but this week they don't:

Four 5W dimmable LED downlights. Varilight 100W dimmer - minimum load either 0W or 10W depending which spec you read. This dimmer goes through an auto-setting either when it's first switched on or evoked by pressing the on/off switch several times. It defaults to trailing edge.
It goes through the setting procedure but not always.
On this occasion the lights don't dim at all....even harsh language doesn't work.
They remain at maximum brightness.
Changed the dimmer - no difference.
Could it be that there's not enough load? I've fitted small numbers of LED d/l s before without issues.
Could it be that the cpc connection has a break between switch and one or more lights? I didn't think LED dimmers needed such an 'earth' reference to work - but happy to be corrected.
Just got some more dimmable LEDs to try not hopeful...
I have had problems with Varilight dimmers buzzing but they've always worked in the past.
What do you think?

 

[Octopus]

I would try a different dimmer .......... the guys behind the counter at my local TLC are not very complimentary about the latest Varilight LED dimmers .................

As for the CPC - that should be irrelevent.

 

[rolyberkin]

What varilight dimmer have you got and have you programmed it? You need to try all three settings, call their customer service department if you are not 100% au fait on how to program as they are very helpful and will walk you through it. If it is something else they will know what.

 

[Dave Jenkins]

Dimmer currently fitted :
VL KDQP101S 1 Gang 2 way V-COM LED Dimmer Switch 1 x 100w
Purchased from TLC. According to the blurb should be an ideal fit.
Programming - following the procedure in the instructions to the letter for both dimmers.
Lamps?

 

[Octopus]

Are you dimming LV LED's or GU10 LED's?

 

[Dave Jenkins]

GU10s

 

[rolyberkin]

You say you are following the instructions but have you tried all three settings? Have you factory re set the dimmer? Have you telephoned varilight customer support?

 

[Dave Jenkins]

Yes, phoned 'em.
They've given me a couple of things to try. Apparently the default setting is Leading Edge not Trailing edge as I thought, so first thing to try...
They also suggested replacing an LED lamp with a Halogen lamp as a test - adds more load...

 

[rolyberkin]

Last time I had a problem with one of these dimmers I found that the LED's only responded on one of the three driving modes, look in the instruction manual and try changing the driving modes to see if that has any positive effect. Try them each in turn to see what works best.

 

[Dave Jenkins]

Yes that was one of the other things to try. Since I've given up for the day I pick it up again later in the week...

Thanks for all your help guys - much appreciated!

 

[Dave Jenkins]

Solution:
I sorted the problem earlier this morning.
I changed the dimmer switch to a Varilight V-Pro version and fitted a halogen lamp in place of one of the LEDs as advised by Varilight for the duration of the test.
The halogen lamp showed the dimming function better than the LEDs.
No matter which mode the switch was in it still wouldn't dim the LEDs, so I replaced them too.
Finally, put the switch into mode 2 and everything was once again right with the world..
Lamps that worked weren't anything special - box of 5 from Screwfix.

 

[jackhammerJIM]

so by the sounds of it the original lamps were non dimmable ?

 

[Dave Jenkins]

That would appear to be the case. K got them from Denmans and specified dimmable LEDs. I'll check the invoice when I locate it.....