DD XML U2 vs T6 (photos)

Flashlight Modding and DIY Parts
7

Nah, under magnification they all look that way. Try you own emitter and snap a macro picture of it . Discoloration is normal on white PCB, and the pads are pre-tinned.

8

no its new LEDs

as pulsar said, its normal to see these colours and pad is pre tinned

some scratches in pads due to previous test point hits

however emitters are not cleaned after reflow process. its very common for such suppliers even we found dirty emitters in flashlights too.

9

Excuse my ignorance but what is the difference between a u2 and t6? It’s the colour right?

10

The U2 is more efficient, this generally is because it is a bluer tint (less phosphorous) but not always. (U3=Brightest, U2=fairly bright, T6=bright, T5=less bright...)

11

U2 is higher bin than T6
U2 produce more light than T6 (same current)
but in here we can’t see any differance in light output.

12

Scaru gave a good explanantion; here's some more info on brightness and tint bins - two different measurements.

Info on luminous flux (brightness):

http://flashlightwiki.com/Brightness_Bins

This info is for tint only:

http://flashlightwiki.com/File:Ansiwhite.jpg

13

@Pavithra_uk: have you possibly tested output at higher currents? Do you actualy recognize any difference?

I’ve got black PCB U2 from DD. Wierd, it might happen I’ve got just T6. Anyone else got black PCB U2 drom DD?
Ah, found this: Inexpensive Sources for XML-T6 or U2 , but no final verdict on difference versus T6.

14

So what’s your call? Are these U2 real or it’s T6 aka U2, the DD way?

15

Very hard to tell the difference between T6 and U2 by looks, higher end T6 vs lower end U2 would be practically identical. DD even has the white PCB in T6 bins, so that makes it even harder.

I've got three black T6s by the way. Just FYI, the black star has weak top layer, very easy to delaminate. Don't force the pad too much after soldering.

16

@ledoman:
I didnt test high currents. at higher currents its even hard to compare by eye
I have no lightmeter to test actual lumen outputs

17

You don’t need lightmeter if you have decend photo camera. You just have to set different short exposure times in manual mode. If you put same current and same reflector giving same runing time (led temperature) or even better pot both leds side by side then you have to see difference on the pictures. You just have to assure the same running condition to both leds. Then you can get something like this (P7 versus XM-L, identical reflectors):

18

And best way to clean emitter is?

19

Isopropyl alcohol and q-tips is standard method. I found that contact spray is also excellent for this purpose…

20

I got my leds from DD, 4pcs T6 for $14.36. I thought I will never get them.
I measured all at 700mA, and got from 285 to 300 lumen. I have a reference T5 xm-l from KD, this can 270 lumen. Another xm-l (salvaged from an ebay light) can 265 lumen, probably this is a T5 too.
So I think the xm-l T6 from DD are really a T6. Unfortunately I did not order the U2 version. :frowning:

21

Can we trust these star/round MCPCB boards ? most 16mm boards that come with XML will not have better thermal conductivity between aluminum & pad

22

I did a quick measurement with a 16mm and a 20mm star. The leds were mounted on a big alu heatshink, and were driven at 3A for 2 minutes.

Brightness drop was ~6.5% with the 16mm Dino xm-l, and ~5% with the 20mm T5 xm-l.

heatshink

Dino xm-l 16mm initial brightness: 920lumen, end of the test: 860 lumen

20mm xm-l T5 initial brightness: 880lumen, end of the test: 838lumen

23

920 lumens from 3A? I'd have thought we need 4A+ for that. Cooling must be a big part of it.

Did you measure the temp of the heatsink?

24

920 lumen but this is pure emitter lumen without any limiting factors, like glass lens, reflector.
Just take a look at the cree datasheet, T6 can provide 910-975 lumen at 3000mA.
The heatsink was only slightly warm, not more than 35°C.

25

I got 2 pcs “U2” from dino. They are T6 not U2 as I measured. One led is salvaged from a light, some thermal glue stayed on the bottom side of the star, and there were 2 solder blobs on the ± solder point. Typical dinodirect…

26

You better be getting a partial refund for that. U2 is priced about $1 higher.

Screw DD. Fasttech just added these T6s... for just a bit more than DD (buy 3+ will lower the price a lot). Now I can finally be off DD for good! Yay.