# LED light unit failed



## sciencefiction (10 Feb 2014)

Hi all,

I have custom made LEDs that just happened to fail all of a sudden. The guy that made them has disappeared and I have no idea if I can fix them and how.

They are three separate strips of LEDs installed on aluminium bar as heat sink, each bar has with its own driver and plug so not sure why they all failed about the same time plus/minus a couple of weeks.

The LEDs he used are High Power 3W CREE XM-L's, 15 LEDs on each bar, connected to this driver model on the link below.

12-18*3W LED External power supply (AC85-265V) [JNY-L3060W-B] - $9.99 : Wayjun Technology,  Focus on the production and development of LED

The symptoms are: one bar blinks, sometimes works fine. Two of the bars switch off completely, sometimes if I let them off for a while they may start and work for a couple of hours.

Has anyone got any idea what I can do?


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## ian_m (11 Feb 2014)

I suspect the single item that sums it up is $9.99 for LED driver....

You are already using decent LED's (good choice CREE) yet drive with something cheap and wonder why it stops working....hint hint hint.

Try something proper like this...
Buy LED Drivers LED Driver,54V,IP64 Power Supply, 40W RS HLN-40H-54A online from RS for next day delivery.


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## sciencefiction (11 Feb 2014)

Cheers Ian. It was someone else that made the lights so I had no clue. I was robbed either way 
Is that driver from the link going to be ok specifications wise for one strip. The strips are 15x3W=45W each?


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## ian_m (11 Feb 2014)

sciencefiction said:


> Is that driver from the link going to be ok specifications wise for one strip. The strips are 15x3W=45W each?


No, not powerful enough, you need obviously need at least 45W 650mA driver. Can't see one at the moment that jumps out from RS. You can of course split each bar into say 25W @ 650mA, but then wiring and no of drivers becomes large (and expensive).

Are you sure they are Cree XM-L LED's (the XM-L's I found are 10W ?) and how are they protected from damp and water from the tank ? That may be your issue of course.

Also 3 x 45W LED is a humungous amount of light, I assume that is over a suitably humungous tank ?


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## ian_m (11 Feb 2014)

Here you go, 700mA 45W driver, from OSRAM.

4008321664433 - OSRAM - LED DRIVER, 45W, 0.7A, 120V | Farnell UK

Switch settable at 700mA, 500mA & 350mA but interestingly has a variable mode, put about 2-11V from potentiometer into control pin to vary the current. Handy for algae control....


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## sciencefiction (11 Feb 2014)

Thanks Ian.

Yes, the lights are Cree XM-Ls.

I am totally not sure what the issue is, not an electrician either. There doesn't seem to be a circuit break because they do switch on from time to time just when they want to. One bar blinks but then it will work eventually if I switch it off for a few min.  Here is a picture of the light unit, each strip is on separate plug and driver


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## ian_m (11 Feb 2014)

sciencefiction said:


> One bar blinks but then it will work eventually if I switch it off for a few min.


Sounds like failed driver, if it's intermittent.


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## sciencefiction (11 Feb 2014)

Yes, it's intermittent but everyday, barely work to keep the tank going.
Thanks so much for your help.
 I am going to buy new drivers and see how it goes.


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## nbaker (2 Mar 2014)

I made my own led light unit and have had similar problems.

In my case the unit was getting damp and individual leds were failing the result was all other leds were lit but very dim and sometimes flickering.


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## sciencefiction (2 Mar 2014)

Thanks nbaker. The LEDs are actually not failing from what I can tell. They are brightly lit if the strip lights up at all.
I still haven't tried replacement drivers, waiting for funds, bad times unfortunately


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## sciencefiction (26 Mar 2014)

ian_m said:


> Here you go, 700mA 45W driver, from OSRAM.
> 
> 4008321664433 - OSRAM - LED DRIVER, 45W, 0.7A, 120V | Farnell UK
> 
> Switch settable at 700mA, 500mA & 350mA but interestingly has a variable mode, put about 2-11V from potentiometer into control pin to vary the current. Handy for algae control....



I ended up buying this one Ian after all three bars gave up working for good unfortunately. My poor plants are gone ape blahblahblahblah, melting, couldn't buy a driver for two weeks.....
Now a few stupid questions.

 I bought the driver you recommended to test it first with the intention to buy two more for the other strips if it solves the problem and works fine.
There are dip switches and it's currently set to 700mA, would this be the correct one?
 I've no idea what potentiometer is, is it for dimming?
I connected the 3 input wires from the mains to the driver on L/N and ground and output from driver to LEDs is red to positive and brown/black wire to negative connected to the driver. There's a third wire that's insulated with the red and black but it was not connected to anything originally and the LEDs light up without it.  It's yellow/green like ground wire colour. I just left it insulated?
It's working now , Lights on...... I am just afraid I did something wrong. I am total newbie when it comes to these things ...

Thank you so much for your help


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## ian_m (26 Mar 2014)

Yes set the DIP switches to 700mA (DIP1 off, DIP2 On). Obviously setting to 500mA or 350mA will be not as bright.

I would wire up as below:


 
I suspect the yellow/green wire, you talk about, is an earth wire. You need to check & confirm. The metal work of your LED bracket MUST be earthed, as shown above in my Green/Yellow connection. If there is a fault, eg live wire comes loose, LED driver catastrophically fails and the live mains ends up being connected to the metalwork, the fuse(s) would blow disconnecting the mains. If you didn't have the earth it would present a serious potential shock hazard upon a fault. In this case hope that mains is on a RCD protected circuit, which is not really the way to protect yourself.

Interestingly with the LED drivers you have if you set the DIP switches to both off, you can control the brightness via a potentiometer. eg http://uk.farnell.com/te-connectivity-citec/23esa473mmf50nf/potentiometer-lin-47k/dp/350096

This is my interpretation. You could connect to more than one driver module by connecting one +12Vset wire to the potentiometer from first module and Vset and GNDset wires to all modules. This would control all modules.


 
This is from the data sheet if you want to control only one module.


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## sciencefiction (26 Mar 2014)

Cheers Ian. This was very helpful.
There is a green/yellow wire on both cables the one from the mains to the led(which I've connected along with L/N) and the one from the driver to the lights. This one I haven't connected, only the red and black.
The original driver was connected only via red/black from the driver to lights without ground and same from mains to driver, the ground was not connected at all on both sides, just cut off.

So should I connect ground on both sides? I think the metal work of the LED is not earthed. The cable comes out from one side and I opened the LED metal frame to check what cables come out of it. There's just a red and black cable coming out connected to the black and red on the round cable which has the third green/yellow cable inside it but it's not connected to anything at all.
As I mentioned above the ground wire was not connected at all to or from the old driver as well so should I connect it anyway?

Thanks again. I won't switch on the lights till I am sure it's right or you'll never here from me again 
The ports of the driver are here:
http://www.osram.com/media/resource/hires/340448/219286/OPTOTRONIC OT 45220-240700 LTCS.pdf

On the wiring diagram on page 3 it shows the connections the new driver has. I've connected mains black/red to L/N and green/yellow (1 wire) to PE/FE ground
Then from the driver to the LED the red and black are connected to the bottom red and black connectors on the driver(wiring diagram page 3) which are indicated as LED + and -. If the ground wire is to be connected too on this side, which port on the driver is the ground output to LED unit?(though as I mentioned the LED unit has just red/black connected/coming out of it, and no ground wire)


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## ian_m (26 Mar 2014)

The LED driver earth is labelled PE (protective earth) and has an earth symbol on it and page 6 of above says you should connect it.

You should also connect any "touchable metal" with electrics on to earth as well. That is what I suspect your third green/yellow wire is/was for, for connecting to the metal of the LED mount.


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## sciencefiction (26 Mar 2014)

ian_m said:


> The LED driver earth is labelled PE (protective earth) and has an earth symbol on it and page 6 of above says you should connect it.



I've connected the green/earth from mains to the LED driver (PE/earth port).



ian_m said:


> You should also connect any "touchable metal" with electrics on to earth as well. That is what I suspect your third green/yellow wire is/was for, for connecting to the metal of the LED mount.



Should I connect the green/earth wire from driver to LEDs although the ground wire isn't connected to anything on the LED side? If I have to connect it, first which output(to LED from driver) port on the driver is the 2nd ground connection? And then should it be connected if there green/ground wire is not connected,just insulated inside the cable and it isn't touching the metal frame/LED side part?

Sorry for the mountain of questions, just not sure and I am useless as you can see.


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## ian_m (26 Mar 2014)

sciencefiction said:


> I've connected the green/earth from mains to the LED driver (PE/earth port).


Correct.

Ideally you need a connection, like below, my green/yellow wire, connecting the metal of your LED frame to mains earth, this sounds like what the third yellow/green wire in you LED connecting cable was intended for, but never connected. Connect it to the metal of the frame by a bolt for instance.



 
However, as this is not a product on sale and if you trust the isolation of the LED driver and your mains sockets are on RCD's you could leave the earthing of metal out  Bit surprised it wasn't earthed in first place.


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## sciencefiction (26 Mar 2014)

Thank you so much Ian. Yes it wasn't earthed at all  I hadn't a clue for the last year. It wasn't me obviously making the custom lights...The lights are actually connected to a surge protector, not sure if that makes a difference....
I'll try to fix the earth connection to LEDs asap.


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## ian_m (26 Mar 2014)

An RCD, residual current device, detects the mismatch between the current in the live wire and current in the neutral wire. If there is a difference (usually 30mA) it means the "electricity is leaking" away somewhere.

If you touched your LED mounting bracket that was accidentally connected to live due to a fault, the RCD would detect the current mismatch due to the current going through you and cut the power before it did you any death type things....hopefully. Most modern houses will have RCD's on the mains and even more modern have RCD's on the lighting circuits as well. If your house hasn't got RCD's (or modern RCBO = RCD + overcurrent in one device) all you aquarium electrics should be on an RCD in cause of "incident", especially as water in involved.

As for surge protectors, known in computer trade as "chocolate teapots". They designed to stop mains surges damaging delicate equipment. Couple of issues, proper surge protectors that work cost serious money and in UK actually have very good surge free mains supply. Our super UPS/surge suppressor at work once recorded a couple of spikes of 270V and drops to 225V but in the 6 odd years of logging zilch really.

This is proper suppressor that works, but cost £100.


 
This is a home cheapy mains suppressor.


 

Here is a chocolate teapot.


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## sciencefiction (17 May 2014)

Hey Ian, one of the light strips failed again. This time it isn't the driver as I connected the driver to the third strip and it's working on it.

I noticed a couple of days ago that one of the leds on the very end of the failed strip was kind of dimmer than the rest. Today it just failed to turn on. It was working yesterday.  I tested with both "working" drivers and the entire strip won't light. Could it be a break in the circuit if one led light fails then all of them fail to work. I've no idea how this guy has connected them inside the light unit itself.


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## ian_m (17 May 2014)

You are using Cree LEDs so doubtful it has failed, though of course if your previous driver had damaged it then maybe.

I would therefore suspect wiring fault. You should just be able to bypass the failed LED with a temporary piece of wire and see if the rest of the string works. You will have to use your Sherlock Holmes head to fault find. You have started already and proved the driver is working.


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## sciencefiction (17 May 2014)

ian_m said:


> You will have to use your Sherlock Holmes head to fault find.


 
Ha, ha, more like Mr. Bean head here.
I'll have to take it down, figure how they are connected and try I guess.

Thanks very much for your continued support. Very much appreciated.


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## limz_777 (18 May 2014)

how long did that china led driver last ?


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## sciencefiction (18 May 2014)

limz_777 said:


> how long did that china led driver last ?


Less than a year, actually less than 9 months I think


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## sciencefiction (21 May 2014)

Hi again.

I took off the led strip that failed and haven't done anything yet but the led that had lost brightness before the strip failed altogether looks very dodgy visually. Like it has failed really because the colour of the little bulb has changed from lemon yellow to darker yellow. So I suspect it is the one bulb that failed and not a connection. I would presume they are wired in series for all of them to fail to light up if one fails?

See on the picture below. The right light is the one that had gone dim/possibly failed(dark yellow) and the left one was a working one(lemon yellow). All working ones on the other strips are lemon yellow.

Do you think it was the old driver that damaged it? Also should I run the leds on 700mA or 500mA? What difference does it make?






The wires are inside the aluminium body. I can detach the failed bulb from the strip, take off the lenses and then take off the wire from the star itself where they are soldered.  What's the easiest to bypass the failed light? I don't even have a soldering iron.[DOUBLEPOST=1400660797][/DOUBLEPOST]The lenses came off easily so this is how it looks inside, bad job to start with?

There are two wires going to the right side and one on the left. This is the first led on the strip from the power cable side.
The rest of the leds have just one wire soldered on both sides.


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## ian_m (21 May 2014)

Well it possibly looks damaged, the yellowing & browning of the chip.

This can be caused by
- Thermal overload due to too much current
- Thermal overload due to not being heatsinked sufficiently
- Not being a Cree device, but cheap Chinese copy.

Looking at your picture and knowing CREE product packaging, this doesn't look like a Cree product. (maybe wrong, might be old Cree product). Search for "cree star" in google images, you will get loads on star PCB shapes, but Cree LED's tend to be square rather than round and have Cree printed on the PCB (maybe wrong of course).

An interesting match I found is this
http://www.ledsales.com.au/shop/index.php?main_page=product_info&cPath=148_188_221&products_id=1334

An LED package that matches is....Warning word here is "Taiwanese"
http://www.ledsales.com.au/shop/index.php?main_page=product_info&cPath=148_188_221&products_id=984

So your LED's could be from same country of manufacture as your LED driver......

In the mean time unsolder the two wires from the failed LED and join them together, simple "chocolate block" connector is fine for testing. Or for even quicker testing just hold a short piece of wire across the two soldered joints or use a pair of pliers anything to electrically bypass the failed LED.


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## sciencefiction (21 May 2014)

ian_m said:


> Looking at your picture and knowing CREE product packaging, this doesn't look like a Cree product. (maybe wrong, might be old Cree product). Search for "cree star" in google images, you will get loads on star PCB shapes, but Cree LED's tend to be square rather than round and have Cree printed on the PCB (maybe wrong of course).


 
Thanks Ian.
I am not surprised. I already googled a bit and had my doubts about these being Crees,  possibly cheap leds too along with the nice Chinese drivers [DOUBLEPOST=1400669212][/DOUBLEPOST]





ian_m said:


> - Thermal overload due to too much current
> - Thermal overload due to not being heatsinked sufficiently
> - Not being a Cree device, but cheap Chinese copy


 
Could I be running them on too much current with the new driver? It's on 700mA, should I changed the dip switches to 500mA or not?


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## sciencefiction (21 May 2014)

ian_m said:


> An interesting match I found is this
> http://www.ledsales.com.au/shop/index.php?main_page=product_info&cPath=148_188_221&products_id=1334


 
He, he, these look exactly like mine. I am not even pissed off anymore.  I'll try to fix it if it isn't costing too much. But I feel like binning them all.


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## ian_m (21 May 2014)

sciencefiction said:


> Could I be running them on too much current with the new driver? It's on 700mA, should I changed the dip switches to 500mA or not?


Well if they are Cree LEDs rated for 700mA (as your original driver was) then 700mA is OK, but watch your algae as thus could be a huge amount of light.

Could of course be a failed Cree LED due to thermal issues. If it had not been attached fully the bar and overheated, it could have failed that way. Check if firmly attached to aluminium bar heatsink. I know a lot of early on DIY aquarium LED lights had failures due to the sticky thermal pads failing due to moisture allowing LEDs to come loose, which then over heated and failed.

However, if you suspect they are not Cree LED's you have to use your judgement. 500mA may prolong the life of the LEDs, but have you enough light then ?

Genuine Cree 3W star LED's are about £5 or more each, but no longer made.

Your LED's resemble Luxeon products, especially as you have the lens/optics, again no longer made (acquired by Philips ?).

However these @ £3 each, Lumiled star series look very similar and rated 700mA and not Chinese rip-offs.
http://uk.farnell.com/lumileds/rebel-star-es-nw200/led-rebel-star-es-nw200-700ma/dp/2115405

You would need to ascertain if your lens/optics will fit and how to attach to your aluminium bracket.


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## sciencefiction (21 May 2014)

ian_m said:


> Could of course be a failed Cree LED due to thermal issues



No, I don't think they are Cree's. I was ripped off definitely.



> Check if firmly attached to aluminium bar heatsink.



Yes, firmly attached.



> Well if they are Cree LEDs rated for 700mA (as your original driver was) then 700mA is OK, but watch your algae as thus could be a huge amount of light.



They are very strong as they can burn the immersed plants near them but I've always ran them suspended above the water surface and never had algae in this tank. Now actually there isn't enough light going down there as the strips haven't worked together at the same time for months due the drivers and most my submerged plants melted. The immersed have overshadowed the tank a lot too.



> However these @ £3 each, Lumiled star series look very similar and rated 700mA and not Chinese rip-offs.
> http://uk.farnell.com/lumileds/rebel-star-es-nw200/led-rebel-star-es-nw200-700ma/dp/2115405



Thanks for this. I'll have a look and possibly try them.

Just one question, what soldering iron can I buy that's cheap but sufficient to re-solder a few failed leds(presuming they'll keep failing  )
I'll be definitely saving for a decent led fixture but it doesn't look good at the moment.


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## ian_m (21 May 2014)

http://www.tlc-direct.co.uk/Products/TLS125.html
or
http://www.maplin.co.uk/p/30w-soldering-iron-mains-powered-n38ac
should be OK.

Just need to be sure tip is fine enough and not something monster and far to big to be of any use, though at 30W must be small.


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## sciencefiction (21 May 2014)

Thanks Ian, just one last question, do I need to use a certain type of solder wire?


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## ian_m (21 May 2014)

Personally I would cut the wires off the failed LED and wire together (in the housing) using 2A version of these
http://www.tlc-direct.co.uk/Products/TLCON2.html
Also available B&Q, Maplin etc.

As for solder has to be lead free and preferably flux cored. Maplin sell I in short affordable lengths.


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## sciencefiction (23 May 2014)

Hi Ian,

I need to buy a third driver for this strip as I only bought 2 Osram ones which are on the working 2 strips.

 I came across this one below from the same website. Is it any worse than the Osram or better do you think? For some reason in pounds it's around £38 from co.uk but from the Irish website it's €46 where the Osram is £29 from co.uk but €50 from the Irish so to me the below works out slightly cheaper though I don't care for the €4 difference but just curious what you think..

http://ie.farnell.com/lumileds/929000614503/led-driver-ac-dc-0-7a-80v/dp/2115974?Ntt=929000614503

I ordered 2 amp chocolate block connectors and will test the strip bypassing the possibly failed led and will order the leds you recommended too to replace when I train myself in soldering. Do I need a multemeter to test the connection after I solder a new led or if they light up I am good to go and can save myself the money for a multimeter?


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## ian_m (23 May 2014)

Its OK for 700mA but unlike the earlier one hasn't got switch settable lower currents. Can be used to dim lights but only with external controls.

The LED type you should be looking for replacements need to be the same star type package that will be suitable with your lenses. You will need to check this or else you will replace your LED's and find the lenses won't/don't fit.

If they light up I assume good to go.

If you want a multi meter just for testing connections any cheap one like this will do. http://www.tlc-direct.co.uk/Products/TMDM1.html. As long as it has a resistance setting, though more useful is audible continuity, ie if beeps if connection is good.

Personally at home I have http://www.tlc-direct.co.uk/Products/TMDL9206.html, which I got as it has a large easy to display and auto-ranging. I have worked with so many meters where hard to read display makes them hard use. My last meter I bought whilst at school (has move'y needle type meter) in 1980 and still works and is still used. But then my career is electronics.

Last time I was in B&Q I noticed they has a range of multi-meters at quite good prices.


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## sciencefiction (23 May 2014)

Thanks Ian so I'll stick with the Osram model.

I am not sure how to check if the lenses will fit but they have the diameter of the star pcb which is 2cm and it has just two holes/dents on the bottom of the plastic cover at opposite sides for the two cables soldered to the star to come out, nothing special really. The lenses is glued to the star with some "white residue glue" which I am suspecting is superglue?

I'll just order a couple of stars and check before soldering  I couldn't see the measurements of these from farnell.
I'll probably ruin one of them first so I am getting a couple of spares


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## sciencefiction (11 May 2016)

Hey Ian, I am reviving this thread again as I still haven't fixed the lights. I was delaying it for ages because I wanted to buy proper light but to be honest even shop purchased ones have been failing on me these days so no point spending a fortune for a 5f tank light if I can learn how to fix these.

The drivers you suggested as replacement are perfect and still working fine. Thanks. The problem is two of the LED bars have not been working in years due to a failed LED on each, subject to further identification..... I took out one of the led strips last Sunday and somehow got lucky by figuring out which led is at fault. The soldering job on it was horrible. I bypassed it and the led strip lit up. But I still need to replace the failed led eventually.

I am going to purchase a soldering iron, star leds(perhaps the same ones you suggested back then), thermal pads, etc.. and try to fully fix the lights by replacing the failed leds. Thankfully one of the strips is still fully working after all these years but my plants have been totally struggling with just one strip.

My question is, are the star leds you previously suggested from the links above still the best solution? I was also wondering if it's possible to get some coloured leds because the lights currently as a whole are very "white" and I like a bit of red hue personally? And if yes, which ones that are a match for that setup?

I also haven't grounded them. What's the best way to do that? The power goes from the socket, to the driver where the red, blue and green(ground) wires are connected. . Then from the out connectors on the driver  that lead to the leds,  only the red and blue wires are connected, leading straight to the leds, meaning no ground wire in that section.  There is no "ground out" connection on the driver, just ground in and the latter is connected to the cable part that comes from the socket.
I see that on your diagram from first page that the ground wire should be also coming from the driver and leading to the leds, and there I should connect it to the aluminium body perhaps via a bold of some sort.
I can screw the ground wire to the aluminium body of the light unit on the side of the leds but its other end isn't connected to the driver at all so not sure if that will work? Where is that ground wire supposed to be connected, the part coming out from the driver?

I am sorry for the stupid questions but I have no clue whatsoever as you can see....

Thanks a lot.


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## Dr Mike Oxgreen (11 May 2016)

The output from the driver will be much lower voltage than the input to the driver. Probably about 12V, which isn't capable of pushing significant current through the human body and therefore doesn't need any earth/ground.


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## ian_m (11 May 2016)

Morning again...

did you ever get a soldering iron ? I notice Ebay sells tin/lead solder (60/40 Sn/Pb), this solders a lot easier than lead free stuff as it tends to "wet" a lot easier. But is not environmentally friendly (though that is debatable) and cannot be sold in a commercial products manufactured after 2006.

Yes you can change any LED to any colour you like, provided they are rated 700mA, the same current as your white ones. You need to look at some commercial LED lights to gauge how they mix their ratios of white, red, green and blue to get some idea of what you should be aiming for. Another option is to change some to warm white, as it sounds like yours are cool white.

The earth wire, if you decide to fit it is as per my diagram on below.





Not strictly necessary as the "proper" LED drivers, at least the Osram ones are properly insulated, it quotes 3700 Volts isolation mains in to LED out. A lot of commercial LED fixtures, made of aluminium are not earthed I notice, as they only have two wires connecting to the fixture.

What the earth does is provide a current path big enough to blow any fuse or trip a breaker if the mains live accidentally gets connected to the aluminium. Thus cuts the supply before the current passes through a person touching the aluminium (a bad thing).


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## sciencefiction (11 May 2016)

Thanks Ian. I never bought anything at all. I'll take a look at the soldering iron.

The earth wire, do I need to connect a separate earth wire to the earth-in that goes in the driver? And if I connect it via a bolt to the aluminium body, do I need to insulate the part of the bolt that will be on the outside in case I touch it?
Basically from the setup on the diagram above everything is connected by the earth wire that comes out of the driver and leads to the aluminium body.


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## sciencefiction (11 May 2016)

Dr Mike Oxgreen said:


> The output from the driver will be much lower voltage than the input to the driver. Probably about 12V, which isn't capable of pushing significant current through the human body and therefore doesn't need any earth/ground.



Thanks Dir Mike. It would be easier if I don't need to connect earth wire from the output because that's a lot of wires that will be hanging from 3 led bars 
I have been using just one led strip without being grounded for a few years now. I've avoided touching it when on


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## markk (11 May 2016)

A couple of things to bear in mind if you replace the damaged/broken LEDs.

- whatever you go for, think about using some thermal adhesive to attach them to the heatsink. The most likely cause of failure was heat damage - and, assuming they were attached with thermal pads - these are the worst option for conducting heat.
- think about replacing a few more than just the broken ones. It's unlikely that you'll get an exact colour/brightness match to the existing LEDs and having just 2 of a different type will likely look a bit strange. If you want to, for example, mix in some warm whites to soften the output a bit - then you'll definitely want to change a few - I'd say at least 1 in 5 and maybe 1 in 3 - and spread them evenly.
- LED lenses are designed for a specific range of LEDs (or sometimes a couple). It's likely that they won't work as well with a different brand of LED - the focus/beam will be different and/or they will reflect less efficiently.

Cheers, Mark


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## ian_m (11 May 2016)

sciencefiction said:


> The earth wire, do I need to connect a separate earth wire to the earth-in that goes in the driver? And if I connect it via a bolt to the aluminium body, do I need to insulate the part of the bolt that will be on the outside in case I touch it?
> Basically from the setup on the diagram above everything is connected by the earth wire that comes out of the driver and leads to the aluminium body.


If you want to connect an earth wire, it should be bolted to the exposed aluminium anywhere you might touch it. However the LED driver outputs are isolated and low voltage thus you probably don't need an earth connection to the aluminium heatsinks. I would still put the earth to the LED driver though.


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## sciencefiction (11 May 2016)

@ian_m .  Thanks. The earth to the LED drivers has always been connected; well, at least since I got the new drivers and followed your instructions, because the old ones didn't have an earth input at all. I am so thick I hadn't even noticed 

@mark Thanks Mark.  The pre-existing setup has some black paste between the star and the aluminium. I am assuming its thermal adhesive. One of the led strips has been working for over 3 years with a few weeks break when the driver failed so the overall design isn't that bad, It's the quality of the components that is the problem .I am going to buy thermal adhesive for sure when I buy the leds. I know as much from fiddling with computer processors...  Is there any specific type that is best?

OK. I'll look into buying lenses as well.  I am going to try to get star leds with the same size and output as the old ones, just a reliable brand. Is 700mA, 3W leds, star shape all I am looking for or are there any other specific details I should be looking for?  What about angle? I am seeing most are 120 degrees? Hopefully they won't look much different appearance but I can come to grips with a bit of a variance as it won't be noticed when they are on. The ones I currently have are 700mA 3W cool white star leds, 2cm in diameter. I need to "warm" the light output a little 
The current setup has 15x3W leds on each of the strips. What would be the general recommendation if I want to mix in some colour in terms of adding blue/reds? Is it better if I change leds on each strip or perhaps leave one as it is with cool whites and add some colour to the other two strips?


I'll keep you guys informed ones I do it. It may not happen till June or so but I am definitely fixing them because it will be a waste considering I don't want to spend hundreds on new lights.


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## zozo (11 May 2016)

A while ago i came accross a thread on another forum where somebody complained about a prisma effect in his tank. He called it like there is a rainbow in my tank.. It was caused by the lenses he used in his led fixture..  I have no idea what the beamangle was or if this is typical for any led lens above water. Just a heads up before you buy something useless.


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## sciencefiction (11 May 2016)

Ha, ha, thanks zozo. I am very good at buying useless stuff


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## Christos Ioannou (12 May 2016)

sciencefiction said:


> I I am going to buy thermal adhesive for sure when I buy the leds. I know as much from fiddling with computer processors...  Is there any specific type that is best?



You can try a thermal epoxy like this
Will give much cleaner results than thermal paste and epoxy. I should have used it in my setup but too anxious to wait for shipping.


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## markk (12 May 2016)

> Thanks Mark.  The pre-existing setup has some black paste between the star and the aluminium. I am assuming its thermal adhesive. One of the led strips has been working for over 3 years with a few weeks break when the driver failed so the overall design isn't that bad, It's the quality of the components that is the problem .I am going to buy thermal adhesive for sure when I buy the leds. I know as much from fiddling with computer processors...  Is there any specific type that is best?
> 
> OK. I'll look into buying lenses as well.  I am going to try to get star leds with the same size and output as the old ones, just a reliable brand. Is 700mA, 3W leds, star shape all I am looking for or are there any other specific details I should be looking for?  What about angle? I am seeing most are 120 degrees? Hopefully they won't look much different appearance but I can come to grips with a bit of a variance as it won't be noticed when they are on. The ones I currently have are 700mA 3W cool white star leds, 2cm in diameter. I need to "warm" the light output a little
> The current setup has 15x3W leds on each of the strips. What would be the general recommendation if I want to mix in some colour in terms of adding blue/reds? Is it better if I change leds on each strip or perhaps leave one as it is with cool whites and add some colour to the other two strips?



To be honest, black paste sounds a little more like a heat pad that has degraded a little - especially if that is from one of the failed units.

For the replacement LEDs, you probably want to ignore the 3W bit. The wattage specified is normally the maximum rating for the units - for example, top end CREE XM-L leds are spec'd up to 10watts but most people run them at 3watts - it all depends on the current you give them. If you have any sort of power meter, you could check what your total consumption is currently - I doubt it will be 15x3x3 = 135 watts. As Ian said some time ago, that is a LOT of LED light. My gut feeling would be that they're running at 1w each for a total of about 45watts - though that's just a guess

So I suggest you focus on units that can accept the 700ma from your drivers - as you say on 20mm stars. Most will be 120degree spread - though it does vary a bit.

My preference would be to change the same number of leds on each strip - I'd be too worried about getting warm/cold spots (as in colour temperature) if it isn't an even spread.

regards, Mark


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## ian_m (12 May 2016)

Here is a just as good thermal adhesive, available in UK.
http://uk.rs-online.com/web/p/thermal-adhesives/1558320/


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## zozo (12 May 2016)

I see you have those star heatsinks..  Why not just drill 2 holes and screw on with some thermal paste..  With those epoxies, i guess you need a hammer and a screwdriver to nick them off again if it ever burnes out.. Taping a thread into aluminium aint so difficult, just put the tap in the cordless drill and it runs like going through butter. M3 or M4 thread is all you need. If one ever burns out again you're greatfull you did a bit extra work on it.

Ps, you would need only 1 machine tap.. Not those 3 piece sets of manual tap.


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## sciencefiction (12 May 2016)

markk said:


> As Ian said some time ago, that is a LOT of LED light. My gut feeling would be that they're running at 1w each for a total of about 45watts - though that's just a guess




I think the leds are rated 3W for sure. I don't know what they are running at in practice but they burn holes in plants from 5cm distance. I had to keep them well above my emersed plants.



zozo said:


> I see you have those star heatsinks..  Why not just drill 2 holes and screw on with some thermal paste..  With those epoxies, i guess you need a hammer and a screwdriver to nick them off again if it ever burnes out.. Taping a thread into aluminium aint so difficult, just put the tap in the cordless drill and it runs like going through butter. M3 or M4 thread is all you need. If one ever burns out again you're greatfull you did a bit extra work on it.
> 
> Ps, you would need only 1 machine tap.. Not those 3 piece sets of manual tap.



Zozo, I've no idea what you mean by the above  Isn't the heatsink the aluminium frame itself? How do I "screw on with thermal paste" ? I agree I don't want to stick on those stars permanently considering their fail rate.....There are holes on the aluminium on both sides of each star through which the cables are threaded. The cables are inside the aluminium frame.


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## zozo (12 May 2016)

Sorry science  my bad, i meant the star pcb



And drill 2 holes in the heatsink for each pcb for example at the LT side and opposite and screw them on. If you drill a 2,5 mm hole same widht as the holes in the pcb and tape some M3 tap in the holes or M4 what ever fits best. Then you can screw 'm on and off with little M3 or M4 screws and use thermal paste between pcb and heatsink.
Here is a chart for tap drill size. M3 = 2.5mm drill. M4 = 3.3 mm drill..  Most predrilled and taped heatsinks for highpower led i've seen had M3 thread.

If you have a cordless drill, they have a reverse, put the tap in the cordless dril and tape the thread in the hole the same like you drilled the hole. Once it is in deep enough, reverse to get the tap out again. Most cordless drills are stepless in speed, this means they go faster the deeper you push the button. Just go easy on the speed with the tap. Use the torc controll setting, if you go to deep you do not break the tap. 

It's actualy very easy.. But that's maybe easy to say.. Dunno.. Sorry if i'm not explaining clear enough..

Here i found a video  but the guy is using steel and larger diameter tap.. Aluminium and small diameter tap like M3 is much easier and quicker..


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## sciencefiction (12 May 2016)

Thanks Marcel Zozo.  That's quite clear now 

Thanks everyone for your help. I think I've got all the information I need. It's up to me now to do it right


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## zozo (12 May 2016)

Welcome  and succes.. Hope to see some nice results soon..  SOme red plants would be nice..


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## sciencefiction (13 May 2016)

Thanks Marcel. I won't start the project till June or July. So the thread will go into oblivion for another bit. But for me it's been a unique source of help that I could not get from searching the internet for months. I've no knowledge about that kind of stuff.

Thanks again everyone and Ian for persevering with me for so long


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