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LED MR11 will not work after replacing halogen in IKEA Underverk kitchen range hood

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GregorBrown

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Hello.
I am new here and not an electrician, but I want to ask the experts.

I bought two LED MR11 replacement bulbs for my IKEA Underverk kitchen range hood. I live in Italy.

The hood says halogen only, but I thought I'd try. The hood has no dimmer.

When I plug them both in, it will will quickly turn on and off. If I use only one LED with the other one left halogen, it will work. I am using it this way for now.

Why cannot I use both of the LED bulbs? Is there anything I can do to use both LED bulbs?

The LED bulb is a MR11-1 2.5W 250mA 12V
The halogen is a MR11 GU4 12V 10W.

I have attached photos.

Thanks for your help
 

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I can't think of any reason for this to happen unless maybe one of your LED bulbs is defective.
 

With both leds in you say that they came on briefly and then off. Was this a one time thing or would it happen after multiple times turning switch on and off. If only a one time occurrence could be one of the leds went open. Did you try both leds alongside the halogen to see if maybe one was bad. Why the one led works with the halogen I have no clue.

- - - Updated - - -

This brings up a question of my own. If you apply 12 vac to a led wouldn't this rectify the ac voltage and the next led in the series receive a higher rectified DC voltage.
 

This problem with mr11 leds replacing halogen bulbs has been discussed on other forums. They describe the exact same thing you are experiencing. From the information I found it may be that it has and electronic transformer and the leds don't draw enough power for it to operate properly. I'm not knowledgeable enough to say whether this is plausible. Maybe someone with more credentials will be able to say.
 
I've repaired numerous similar installations, being inside cooker hoods they tend to run too hot for reliability.

The problem, as already mentioned is the electronic transformer. They are typically an oscillator driving a pair of MOSFETS in push-pull configuration to a small toroidal transformer. The secondary is a few turns of heavy grade insulated wire and goes straight to the lamps in parallel. They rarely have voltage regulation or any protective 'cut off' circuits. The output is about 12V but at a frequency around 50KHz. The low voltage LEDs will have a bridge rectifier in them that becomes ineffective above about 1KHz, they are intended to be used on 50 Hz or 60 Hz and no higher.

Brian.
 

Is there anything to do, or should I just use halogen?
 

Good questions.

Each time I press the on-off button, they come on briefly and then go off.

I have not tried switching the two LED bulbs alongside the one halogen to see if one is perhaps defective. I will do so and reply to let you know.

Thanks.
 

The only solution is to remove the existing ballast and replace it with a small ordinary transformer. For LEDs it can be quite a small transformer (~6VA) the reason they don't do that with Halogens is the transformer would be too heavy to mount, it would be a significant amount of the total hood weight.

Brian.
 

With both leds in you say that they came on briefly and then off. Was this a one time thing or would it happen after multiple times turning switch on and off. If only a one time occurrence could be one of the leds went open. Did you try both leds alongside the halogen to see if maybe one was bad. Why the one led works with the halogen I have no clue.

- - - Updated - - -

This brings up a question of my own. If you apply 12 vac to a led wouldn't this rectify the ac voltage and the next led in the series receive a higher rectified DC voltage.

See my reply below. I tried switching out the bulbs, the one is not faulty, unfortunately. It only works with one halogen and one LED. Or both halogens.
 

The only solution is to remove the existing ballast and replace it with a small ordinary transformer. For LEDs it can be quite a small transformer (~6VA) the reason they don't do that with Halogens is the transformer would be too heavy to mount, it would be a significant amount of the total hood weight.

Brian.
Hello Brian
Is that easy to do? I can solder and wire, but I'm not sure if I'd be able to pull out the existing transfer and fit in a LED one in that space. Is there a webpage that shows how this is done?
Thanks!
 

It depends on the type of hood and what space is inside it. A 6VA conventional transformer is quite small or you could use a toroidal one which is even smaller. All you need to do is wire the incoming AC wires to two pins of the transformer and the LED lamps to the other pins. If you use a type with two 12V outputs, wire one LED to each output, if its a single output type, wire the LEDS to it in parallel instead.

I'm not sure if there is a web page, I usually repair the electronic transformers when they go faulty and fit them back again but keep the existing halogens. They are for customers so I can't really modify their products.

Brian.
 

if you don't have the space in fixture for transformer you could mount the transformer in another location like a cabinet above the hood. This would mean bringing high voltage to it then low voltage back down to fixture. I believe there are also dedicated led drivers on the market that might fit in place of electronic transformer. Maybe @betwixt could tell you more about these drivers.
 

It depends on the type of hood and what space is inside it. A 6VA conventional transformer is quite small or you could use a toroidal one which is even smaller. All you need to do is wire the incoming AC wires to two pins of the transformer and the LED lamps to the other pins. If you use a type with two 12V outputs, wire one LED to each output, if its a single output type, wire the LEDS to it in parallel instead.

I'm not sure if there is a web page, I usually repair the electronic transformers when they go faulty and fit them back again but keep the existing halogens. They are for customers so I can't really modify their products.

Brian.

I need to take out the halogen transformer? I think that's obvious, but just clarifying.
And can you point me to a link for a LED transformer?

I suppose I need to determine if this effort and money is worth the Halogen to LED switch!
 

Hi,

Either you look for a dedicated electronic LED transformer / power supply.
Or you use a standard 12V AC transformer.

Klaus
 

Led drivers are inexpensive and compact. You still need to measure the space available so you can be certain the dimensions of the new led driver will fit. I don't think you will have a problem finding one that fits. A quick search on ebay will yield many led drivers. Are you could just drive down to your local electrical or hardware store and find one possibly. I would think one that delivers 8-10 watts would be appropriate for your lights.
 

Led drivers are inexpensive and compact. You still need to measure the space available so you can be certain the dimensions of the new led driver will fit. I don't think you will have a problem finding one that fits. A quick search on ebay will yield many led drivers. Are you could just drive down to your local electrical or hardware store and find one possibly. I would think one that delivers 8-10 watts would be appropriate for your lights.

Just for clarification, a driver is the same thing as a transformer?
And I would need to remove the current halogen transformer that is in the hood?

Thanks!
 

Led drivers transform high voltage to low voltage electronically. Ac transformers are magnetic devices. They have a steel core wrapped with many turns of individual copper wires. They are both transformers in the sense that they will change the voltage from one level to another. But how they accomplish that is quite different.

If the only space available in your hood is where the other transformer is then of course you will have to remove it. Also if your lights have a dimmer there may be compatibility issues to look into if you go with a led driver instead of AC transformer.
 

Led drivers transform high voltage to low voltage electronically. Ac transformers are magnetic devices. They have a steel core wrapped with many turns of individual copper wires. They are both transformers in the sense that they will change the voltage from one level to another. But how they accomplish that is quite different.

If the only space available in your hood is where the other transformer is then of course you will have to remove it. Also if your lights have a dimmer there may be compatibility issues to look into if you go with a led driver instead of AC transformer.

Sorry for the 'simple' questions. ;)
There is not a dimmer, thankfully.
There should be an existing transformer in the hood for the halogen lights? I would remove that, connect the LED driver and connect the lights to the driver?
Thanks!
 

Yes, but first and foremost you need to make sure the power is shut off at the breaker panel before doing anything. You also need to identify which wires are high voltage to the existing transformer so you can correctly wire the new driver or transformer.
 
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