Flashing LEDs - Overheating transformer?

[AdamCH]

I have a 25w max LED transformer powering 2x7w and 1x4w LEDs. Works fine but after a while all 3 LEDs start to flash on & off.

Is the transformer duff or am I using the wrong rating?

 

[ericmark]

A LED needs a DC supply and the current limiting this can be done in many different ways and having electronics built into a bulb and powering it from 12 vac is one method. One may also use a DC power supply possibly with the same bulbs and what you need is for all parts to be matched in some way.

Although we call devices transformers and LED's often they are a lot more than that with switched mode high frequency voltage regulated AC power supplies often been called a transformer and a package with three LED's and a switched mode regulator with rectifier being called an LED where they again are much more.

So question is what are you using.

 

[AdamCH]

Its an Aurora AU-LED2512CV 1-25W 12V DC Non-Dimmable Constant Voltage LED Driver: http://gb.auroralighting.com/Produc...DC-Non-Dimmable-Constant-Voltage-LED-Dri.aspx

 

[JohnW2]

Its an Aurora AU-LED2512CV 1-25W 12V DC Non-Dimmable Constant Voltage LED Driver: http://gb.auroralighting.com/Produc...immable-Constant-Voltage-LED-Dri.aspx[/QUOTE]
Fair enough ... and what are the LEDs? I presume they are suitable for a (12V) DC supply?

Kind Regards, John

 

[AdamCH]

They're also Aurora:

2 x 12V MR16 7W LED: http://gb.auroralighting.com/Produc...-LED-Lamps/12V-MR16/12V-MR16-7W-LED-Lamp.aspx

1 x 12V MR16 4W Non-dimmable LED http://gb.auroralighting.com/Produc...V-MR16/12V-MR16-4W-Non-dimmable-LED-Lamp.aspx

They all flash together after a while so assuming it's the LED driver issue.

 

[ericmark]

Clearly it should work so unless the position where the power supply is mounted is reducing the cooling then yes it's faulty.

 

[AdamCH]

Cheers

It's in the loft mounted to a brick wall so plenty of cooling.

I'll try disconnecting some of the lamps & see if the remainder stay on.

 

[JohnW2]

Cheers ... It's in the loft mounted to a brick wall so plenty of cooling. ... I'll try disconnecting some of the lamps & see if the remainder stay on.

As eric says, the LEDs and that driver appear compatible, so they should work. I suppose that, at 18W, your total load is getting fairly close to the 25W maximum rating of the driver, so it's just about possible that it's overheating; you mention 'overheating' only in the title of this thread - is it getting very hot?

If overheating has been the problem, and if that has not resulted in irreversible damage, then to do as you say and unplug one of the lamps might cure (and therefore identify) the problem.

Kind Regards, John

 

[Taylortwocities]

This may sound obvious but, as the products are all made by Aurora, shouldn't you asking HERE?

 

[bernardgreen]

The "12 volt" output from an electronic "transformer" can be full of electrical noise at the switching frequency of the invertor, it can even be pulses of 24 volts that average out to look like 12 volts.

Feed this chopped up DC as the supply into another switch mode device such as an LED current regulator ( the LED driver ) and the two switch mode devices inter act and all sorts of beat frequencies will be created and this can result making the devices very un-stable.

 

[AdamCH]

My test with less bulbs yesterday evening was interrupted by one of the kids switching the light off. Must be the first time in 20 years that either off them has switched a light off.

Only seems to happen after an hour, but if it is getting too warm I'm thinking it might be best to swap it out.

 

[JohnW2]

The "12 volt" output from an electronic "transformer" can be full of electrical noise at the switching frequency of the invertor, it can even be pulses of 24 volts that average out to look like 12 volts. ... Feed this chopped up DC as the supply into another switch mode device such as an LED current regulator ( the LED driver ) and the two switch mode devices inter act and all sorts of beat frequencies will be created and this can result making the devices very un-stable.

Do I take it that, in the context of this thread, the 'LED current regulator' you refer to is that within the "LED"? Whilst what you say is all theoretically reasonable, in this case the OP is using the 12V constant voltage LED source produced and recommended by the same manufacturer as the LEDs, so one would expect compatibility.

In any event, you may recall that a coupleof months ago I illustrated that an almost identical LED driver (the Aurora LED1012CV - the 10W version of what the OP has) actually produces a surprising clean DC output:

Untitled

• JohnW2
• 9 Jun 2014
• 2

As TTC has said, given that both LEDs and driver are from the same manufacturer, the OP should probably check with them before assuming that the driver needs replacing.

Kind Regards, John

 

[phatboy]

I have seen 1 faulty LED unit cause this sort of issue before

 

[AdamCH]

Thanks for that.

It was something I bought a while ago & didn't use. Doubt I'll find a receipt for it.

I guess it's safest to ditch it.

 

[bernardgreen]

On going confusion between drivers and transformers ( both wound and electronic )

The LED driver controls the current through the LED element and in almost all LED lamps the driver is included as an integral part of the lamp.

The driver is normally fed by a supply that can be anything from a 3 volts up to 230 volts The supply voltage must match that that for which the lamp is designed.

In a few rare lamps there is no driver in the lamp and there has to be an external driver whose current must match the current the LED element needs. The supplied current must match that which the LED in the lamp requires.