16mm Sinkpad Help!

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marcl
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16mm Sinkpad Help!

Hi guys,

I have just re-flowed an XML onto a 16mm copper Sinkpad. But now that it’s in the light the LED hardly lights up. What have I done? Pretty sure I have the + and – the right way.

Thanks

Marc.

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nitro
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can u post a pic ? did u check the driver if that had killed it

marcl
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nitro wrote:
can u post a pic ? did u check the driver if that had killed it

Hi Nitro,

I cant post a pic, sorry, I would have to borrow the wife’s camera. It was working before but not when I switched to a sinkpad. Strange. Sad

By the way it wasn’t from you, so don’t worry. It was a sample they sent me.

Marc.

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dct73
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Try connecting a battery directly to the LED momentarily and see if it lights up. That should tell you if the LED is good or not and you can work backwards from there.

Bort
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dct73 wrote:
Try connecting a battery directly to the LED momentarily and see if it lights up. That should tell you if the LED is good or not and you can work backwards from there.

that could easily toast the LED

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marcl
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Bort wrote:
dct73 wrote:
Try connecting a battery directly to the LED momentarily and see if it lights up. That should tell you if the LED is good or not and you can work backwards from there.
that could easily toast the LED

I won’t do that then Shocked

Marc.

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NightCrawl
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Better use the continuity setting of a DMM, maybe you placed the LED wrong (pos and neg exchanged).

AlexGT
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I have tested LEDs using a 3V 123A with no problems, just a 1 or 2 second burst of light will not damage the LED.

marcl
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NightCrawl wrote:

Better use the continuity setting of a DMM, maybe you placed the LED wrong (pos and neg exchanged).

That’s what I thought, but I made a note of the + and – before I removed the LED and placed it on the Sinkpad, so I am a bit puzzled.

Marc.

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Bort
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AlexGT wrote:
I have tested LEDs using a 3V 123A with no problems, just a 1 or 2 second burst of light will not damage the LED.

impressive, so how did others on this forum toast their LEDs with direct connection?
Did you test 4.2V by any chance?

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Bort wrote:
AlexGT wrote:
I have tested LEDs using a 3V 123A with no problems, just a 1 or 2 second burst of light will not damage the LED.
impressive, so how did others on this forum toast their LEDs with direct connection? Did you test 4.2V by any chance?

The voltage sag limits the current. Direct drive with a hot cell that doesn't sag under load as much (like INRs) is where the LEDs get killed. In the same way, multiple cells in parallel results in lass sag and the LEDs do not like that. They will even survive 2x cr123s in series... most of the time. I have killed one with that setup before, it worked fine for quite a while but eventually something glitched and took it out. I have never killed one with a conventional non-INR 18650.

marcl
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Ok, I have put the LED together with another driver with the same results. LED is very dim but then flickers. This is the first time it has been used and looking back at what I have done the LED was the correct way round on the Sinkpad. So is it possible to just get a bad LED?

Marc.

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comfychair
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Try re-heating the board until the solder melts, you don't need to remove it. If that doesn't fix it it's a bad LED (or it was damaged from too much heat during the first reflow, I have done that more than once). It won't light at all if it's a polarity issue.

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marcl wrote:
NightCrawl wrote:

Better use the continuity setting of a DMM, maybe you placed the LED wrong (pos and neg exchanged).

That's what I thought, but I made a note of the + and - before I removed the LED and placed it on the Sinkpad, so I am a bit puzzled. Marc.

continuity test can't damage the LCD, just try one way and if it does not work try the other way.

You have a red and blue (or black) probe, when (if) the LED lights up, red probe will indicate positive (+) contact...

 

bdiddle
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Reflow the LED.

What I use to test LED’s is a cheapy radio shack AA battery holder with a not fully charged 14500 battery in it.

Just tapped the wires to the solder pads. Will let you know if it is reflowed properly. I had some that looked perfect but no light. Just reheated them on the stove and shazaam.

Newb

Ouchyfoot
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It sounds like one of the contact pads might not have connected up properly during the reflow. Do you tin the pads first, or just use the tinning that comes already on the sinkpad? I always add more solder to the contacts.

djozz
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Yes, reheat it, when the solder isn't hot enough it does not 'retreat' to the separate solderpads fully and makes them short. When soldered well, the solder shines bright and smokes a bit, and the led snaps into place.

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I had a similar prob with a reflow I did a while back and I think it was because the led was over cooked. It worked, but would never pull much current even on direct drive because the Vf was much higher. Replaced the led and was more careful with the heat, job-jobbed. Smile

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Low temp solder paste is your friend while reflowing. Less likely to fry the LED.

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Just my opinion. I would test the led with a 9v alkaline battery with one of these. The 9v can’t supply enough current to hurt the led. Its internal resistance is to high. There are two little pads on the led base that you can touch the wires to for the led test. If it doesn’t light decently bright, then its probably shot. If it does light up well, then its a bad connection from the reflow.
You might have to remove a small amount of silicone off those pads to get a connection.
.

I have had two reflows that I have done seem perfectly fine. Then once the light was operated for a good length of time went dim with flickering. In low mode it seemed fine but when switched to high it dimmed and flickered. I was sure something must have went bad with the driver. Until I tested the led at the base of the led with the 9v alkaline. My conclusion was that the reflow process had made the connection but not a good one. So I figured when the light got hot enough the poor connection broke and would not flow enough current for high modes. But in low mode there was just enough solder contact that the small amount of current flow worked fine. I reflowed the led again and applied a small amount of downward pressure with a carbon fiber arrow tube that I had laying around. Has worked fine ever since. Just my two cents. Smile

marcl
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moderator007 wrote:
Just my opinion. I would test the led with a 9v alkaline battery with one of these. The 9v can’t supply enough current to hurt the led. Its internal resistance is to high. There are two little pads on the led base that you can touch the wires to for the led test. If it doesn’t light decently bright, then its probably shot. If it does light up well, then its a bad connection from the reflow.
You might have to remove a small amount of silicone off those pads to get a connection.
.

I have had two reflows that I have done seem perfectly fine. Then once the light was operated for a good length of time went dim with flickering. In low mode it seemed fine but when switched to high it dimmed and flickered. I was sure something must have went bad with the driver. Until I tested the led at the base of the led with the 9v alkaline. My conclusion was that the reflow process had made the connection but not a good one. So I figured when the light got hot enough the poor connection broke and would not flow enough current for high modes. But in low mode there was just enough solder contact that the small amount of current flow worked fine. I reflowed the led again and applied a small amount of downward pressure with a carbon fiber arrow tube that I had laying around. Has worked fine ever since. Just my two cents. Smile

This sounds like what is happening to me.

Just to answer everyone. I did use solder paste and a little extra solder but not a lot.

I am going to go and re-flow it now and see what happens. Thanks for all of your help. Smile

Marc.

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marcl
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OK, a quick update. It turns out the Sinkpad has been made poorly. The screening/coating was slightly deformed and had raised up a little so more solder and and reflow worked. Smile

One other problem I have noticed is the + is very close to the edge of the Sinkpad. This causes a problem when installing it into a P60. Because the Sinkpad is already larger than the star it replaced the positive wire kept shorting on the pill.

Overall i’m not that impressed with them and looking at the design I think the Noctigon’s that intl-outdoors have, look better. Less filing and arsing around I would imagine.

I am talking about the 16mm Sinkpads by the way. I have a 20mm which looks a lot better to use.

Marc.

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NightCrawl
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If a 16mm shorts out against the pill you need to check your soldering skills. Wink

The solder tabs have been moved to the edge because the wires would get in the way of most reflectors..

marcl
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NightCrawl wrote:

If a 16mm shorts out against the pill you need to check your soldering skills. Wink

The solder tabs have been moved to the edge because the wires would get in the way of most reflectors..

My soldering skills are good. Used to be my job, but on my Sinkpad the solder tabs are almost on the edge of the star. Maybe a tenth of a millimetre. That’s very close even for the best of us. Wink

Marc.

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Ouchyfoot
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Probably best to use them in a pill that will take a 20mm sinkpad. That will give you som wiggle room.

comfychair
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Get some thin teflon sheet and slip it between Sinkpad & pill, if it's really that much of a problem. But, it really shouldn't be a problem. You think the pad location on the 16mm boards is compromised? Check out what you're left with when you cut a 20mm Sinkpad down to 16mm (16mm left, cut-down 20mm right):

And both those are with 22AWG silicone wire.

It's not uncommon at all to have to trim off stray solder with a sharp knife/x-acto/whatever, even when you've got the right amount of solder and it's well-fluxed and what would be, in any other application, a perfect solder joint.

Smile

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 Worked fine for me in a P60 pill:

 

 

marcl
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comfychair wrote:

Get some thin teflon sheet and slip it between Sinkpad & pill, if it’s really that much of a problem. But, it really shouldn’t be a problem. You think the pad location on the 16mm boards is compromised? Check out what you’re left with when you cut a 20mm Sinkpad down to 16mm (16mm left, cut-down 20mm right):

And both those are with 22AWG silicone wire.

It’s not uncommon at all to have to trim off stray solder with a sharp knife/x-acto/whatever, even when you’ve got the right amount of solder and it’s well-fluxed and what would be, in any other application, a perfect solder joint.

Smile

My 16mm Sinkpad is as tight as yours in the pic. In fact it had to be filed down a little. I’m not saying they are rubbish, just saying the noctigon look better designed.

Marc.

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Firelight2
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marcl wrote:

My 16mm Sinkpad is as tight as yours in the pic. In fact it had to be filed down a little. I’m not saying they are rubbish, just saying the noctigon look better designed.

Marc.

My sinkpads arrived last week. Very nice. Are the noctigons better? From the pics and reviews it looks like it. The noctigons aren’t trying to also be 10mm boards, and I think as a result have bigger bond pads. The noctigons also have flat bases without the little indentation below the emitter. It remains to be seen whether the noctigons will need any filing before they fit (my sinkpads needed a little filing and finishing of the edges to fit into a 16mm pill).

On the other hand the Sinkpads are out now while my order of noctigons probably won’t arrive for a few weeks.

Both Sinkpads and Noctigons are probably a vast improvement over conventional thin aluminum boards.

marcl
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Firelight2 wrote:
marcl wrote:

My 16mm Sinkpad is as tight as yours in the pic. In fact it had to be filed down a little. I’m not saying they are rubbish, just saying the noctigon look better designed.

Marc.

My sinkpads arrived last week. Very nice. Are the noctigons better? From the pics and reviews it looks like it. The noctigons aren’t trying to also be 10mm boards, and I think as a result have bigger bond pads. The noctigons also have flat bases without the little indentation below the emitter. It remains to be seen whether the noctigons will need any filing before they fit (my sinkpads needed a little filing and finishing of the edges to fit into a 16mm pill).

On the other hand the Sinkpads are out now while my order of noctigons probably won’t arrive for a few weeks.

Both Sinkpads and Noctigons are probably a vast improvement over conventional thin aluminum boards.

Agree with all of the above. like I said I was only commenting on the Sinkpad as I used it. Not saying they are bad just thought the Noctigons look like they could be more user friendly. I think it didn’t help that the screening on mine was slightly faulty causing problems seating the LED.

Marc.

Eagles may soar, but weasels don't get sucked into jet engines!