Flashing 92 led raimond pendant light

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jules44

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Hi - I bought this 24v light about 5 years ago. It stopped working, so I got a new transformer. But now all the LEDs are flashing, slowly about a second for each flash.
Is it likely to be a faulty bulb causing it? If yes, how do I easily find out which one it is - removing each one would take ages!
Any ideas?
thanks
 
Perhaps when it stopped working, it wasn't the transformer that caused the problem.
What voltage is the power supply you have?
It looks like the light is drawing too much current and the power supply is switching off, then back on again.
Have you still got the old transformer? if so a picture might help.

Just a small note, the powersupply you have probably has a DC output, a true transformer has an AC output.
 
Perhaps when it stopped working, it wasn't the transformer that caused the problem.
What voltage is the power supply you have?
It looks like the light is drawing too much current and the power supply is switching off, then back on again.
Have you still got the old transformer? if so a picture might help.

Just a small note, the powersupply you have probably has a DC output, a true transformer has an AC output.
Here is a pic of the old powersupply, the new one is the same spec. Yes it is a 24v DC output.
1642876253892.png
 
It does look like it is overloading the supply which trips out in response then automatically resets. First be sure that the replacement supply is at least as powerful as the original. Then, how is the fitting constructed? Can you disconnect the leds individually? Can you split them into groups? When it comes on, look carefully if any individual one DOESN'T light; that could be a short circuited chip.
 
It does look like it is overloading the supply which trips out in response then automatically resets. First be sure that the replacement supply is at least as powerful as the original. Then, how is the fitting constructed? Can you disconnect the leds individually? Can you split them into groups? When it comes on, look carefully if any individual one DOESN'T light; that could be a short circuited chip.
I think I'll have to disconnect each one - will take a lot of time as they are fiddly to disconnect. The screws holding each one also hold the structure together. They can't easily be split into groups, other than disassembling the whole thing.
thanks
 
Jules44, thanks for the 2nd picture, I wanted to see could the 2nd power supply provide the same amount of current as the first one.

What happens if you connect the original power supply to the light? (Just to test it, I know you said it stopped working, but does the light flash, or do anything?)
I can not help but wonder if it is one of the 92 LEDs that is causing the problem, I am beginning to think that it is, but this leads to another problem, apart from you having to take out the LED's individually* can you get spare LED lamps? (I have looked, I can buy a complete new lamp but no spare LEDs :( )


* The lamp consists of two spheres, one sphere sits inside the other. Each sphere is made from similar to Meccano (It inspired the designer) The inner sphere is supported at each (Meccano) joint by an LED lamp (Its an LED in a custom made mount)
One sphere is connected to 24v+ the other is connected to 24v-
 
I would definitely want to try another power supply unit first.
I've tried with both these 2 similar power supply units, but get the same result - the whole thing flashes.
 

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That confirms what I was thinking then. One of the LED's has failed short circuit. (If you have the same problem with 2 power supplies, it can not be the power supplies.)
Which unfortunately means you are going to have to test each one by removing it from the light, you can't test "anywhere" as they are all connected to each other (Parallel) But this brings me back to what I said earlier, can you get replacements, I could not find any.

There is however a couple of things you can try. (No guarantee) As the light fitting is made from uninsulated metal, see if the outer sphere is touching the inner sphere, or is there something bridging the spheres. (Other than the LEDs)
The other thing is check all 96 LED's and look for one that has black spots, it will be the one that has failed.

As the light fitting is designed so all the LEDs are in parallel you can remove one and the remainder will still work. (Old lights were wired in series, but caused just as much "fun" trying to find the failed one.)

I wish you luck, sorry there is no easy way, its like Christmas tree lights used to be, hunt the failed lamp. Let us know how you get on.
 
Not an easy task! You may be able to gather some clues by powering up slowly using a variable DC power supply.
A dead short would not power up at all so this can be discounted as most of the LEDs flash. If you can raise the voltage to a point where most of the LEDs glow dimly it should be possible to find the failed LED or at least the faulty branch. I suggest a small 0-15V 3A PSU with current and voltage meters should be suitable. I can loan you a lab supply if you are located near Twickenham.
 
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Not a bad idea marcher, I will extend the offer by saying that if you are in central Scotland I will give you a loan of my variable PSU.
 
That confirms what I was thinking then. One of the LED's has failed short circuit. (If you have the same problem with 2 power supplies, it can not be the power supplies.)
Which unfortunately means you are going to have to test each one by removing it from the light, you can't test "anywhere" as they are all connected to each other (Parallel) But this brings me back to what I said earlier, can you get replacements, I could not find any.

There is however a couple of things you can try. (No guarantee) As the light fitting is made from uninsulated metal, see if the outer sphere is touching the inner sphere, or is there something bridging the spheres. (Other than the LEDs)
The other thing is check all 96 LED's and look for one that has black spots, it will be the one that has failed.

As the light fitting is designed so all the LEDs are in parallel you can remove one and the remainder will still work. (Old lights were wired in series, but caused just as much "fun" trying to find the failed one.)

I wish you luck, sorry there is no easy way, its like Christmas tree lights used to be, hunt the failed lamp. Let us know how you get on.
Thanks for the advice. I checked that nothing was shorting the inner and outer spheres.
Yes, what I expected, I'll have to disconnect 1 by 1 to find the faulty ones. I have some spares that came with the light, but they are difficult to find. I think they are specialist ones that I may be able to get at a boat supply place (that's a different question :) )
It will be a few days before I start to dismantle it.
 
Thanks for the advice, and the offers of voltage meters.
I disassembled the outer sphere, to find the faulty LED.
Unfortunately, it wasn't until the last 8 or so that I found it 😖
With the last 7 connected without flashing, I got a burning smell from one the remaining LEDs.

I've decided to scrap it, can't face having to do it again if another LED fails.
If anyone wants this fixture, they are welcome to collect (Lewisham, SE London). The outer sphere needs reassembly, which will be fiddly.
 
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