LED Reliability

[Tort]

Over the last two or three years we have had an number of LED fittings installed at work on various projects. Ok, so they are architectural types rather than theatrical, but we've had a number of problems with fittings failing in that time. Generally it tends to be the drivers. It doesnt even seem to be the cost of the fitting - cheap ones have failed, expensive units have failed (from brand new!)

 

I was just wondering how the theatre versions fair? I do have six stairville par 56s and two eurolight par 64's which I have used at a few shows. Only had one fail and that was due to a dodgy solder connection shorting out - an easy repair.

 

It does make me a little nervous.

[niclights]

12x Pulsar Chromapanels (both CP600 and 300) running on Chromazone. Over five years old. No problems.

 

42x Showtec P56 LED. One LED board fault from new. One control fault from new. One control fault after 2yrs operation. Over three years.

 

4x DTS DeltaR. Two years. No problems.

 

 

Infinitely more reliable than any moving light I've ever used!

[tokm]

Infinitely more reliable than any moving light I've ever used!

Here here!

 

I must say, with LED's in my experience you do get what you pay for. The Chinese made cans suffer from a whole host of issues (poor quality boards & LED's, miss matched LED's, etc), they're almost treated as disposable items. If they break on a gig, unless its something very easy to fix, you just write them off kinda thing.

 

Course if its something by JTE or Pulsar, first off your less likely to have any issues, be it faults or miss-match of LED's. But on the rare occasion when you do, its worth fixing them as they're much more likely to last longer and give you better service in the long run.

 

That's my take on it anyway..

 

T

[musht]

Things with strings of little LEDs tend to have very simple driving requirements, i.e. series string with a resistor, PWM control by a.n. power transistor miles within its operating headroom.

 

High power , big, LEDs have much more sensitive driving requrements typically being run from switch mode constant current drivers, only in last couple of years has semiconductor industry caught up with this requirement and released current mode driver I.C.s. Previously contorting a voltage driver into current mode was the solution and a number of chip makers have app notes to this end.

 

Switch mode PSU design is a bit of a black art , the frequencies involved are very high and subtle things like length of PCB tracks can have unexpected consequences. Component tolerance can work fine on the prototype on the bench but start having unintended consequences in production. Chopper transistors can go with quite a bang...

 

Colour matching affects even the most expensive LED units, its in the nature of LEDs production, clients seem to understand comparison with print batches of wallpaper. Have held spare LEDs in past from identical batch for subsequent repairs on units that were vunerable to vandalism.

 

It is still a fast developing market and unfortunately price is absolutely no guide to quality.

[adam2]

I too have been very disapointed with the reliability of LED lighting equipment, like the O/P though, my experience has been with architectural lighting, not theatre.

 

Members in London may wish to look at the Hungerford footbridge that crosses the Thames near Charing Cross.

The bridge supports or pylons were fitted with blue LED beacons, expected to last 20 years, over half have failed and most of the rest are now very dim.

A few years ago LED uplighters were installed under the railway arches near Waterloo station, over half have failed.

[musht]

Cost spread between cheap commodity LEDs and big brand LEDs, the Lumileds, Cree, Nichia`s etc of the world, can be huge.

 

Few years ago big name 5mm blue LED could be £3 per LED even in quantity, commodity LED could be found for 30p, prices have come down but could still shave 90% of cost by using a no brand LED and keeping your fingers crossed....

 

Here`s a not nice example from few years back:

 

http://www.electronicsweekly.com/blogs/eng...et-an-unti.html

[sus.lighting]

I have worked with LED lights and in not impressed, as I have come across many different problems trying to control them.

They are not very bright as well so they don't carry light far enough for any decent lighting on a stage, I would invest in some studio lamps with scrollers to get good strong light with the advantage of the changing colors. Depends what desk you have though.

[Modge]

I was involved in an install with 24 thonnman 1w LED pars (didn't spec the kit, just lent him a pre-beta desk, designed stuff and made it all actually work). I was very impressed with the light output of them and the much closer than normal approximation of white they achieved (though I wouldn't use them for theatre necessarily). However in answer to the direct question of reliability at least 6 had died with in 2 months, 2 with in the first fortnight. There wasn't a particular patten to the faults: some lost a colour, some died completely and one just sat there flickering regardless of DMX input or the settings on it's dipswitchs. I believe these units cost about £110 each though I'm told that since they were brought the price has fallen significantly, much to their owners chagrin.