Review and disassembly: Sofirn C8F

I guess you are right :slight_smile:

Turning blue means catastrophic levels of current being pushed through the chip.

I had a “3V-22V” drop-in that I wanted to test to make sure it could handle even only 2 cells, so put in 2 18350s. Got really blue and really dim. Didn’t have it that way for more than 1-2sec tops, pulled the plug. 1 cell back in, the bugger survived.

1 cell?? Dunno how a trip could go blue from only 1 cell like that, even if just crowbarred right across the LEDs.

Unless they separated from the mcpcb and were just floating? Could make electrical contact w/o much thermal contact. That might cook ’em.

It was on no more than a second after turning blue but no help. I don’t understand how would they get so hot that fast. I was using it max 2 minutes before they died but it wasn’t constant on as I was playing with modes.
Interesting is moon didn’t work at all (before it died), leds were off in that mode.

It’s before my time here, but I believe OL did pretty much only DD lights: LED and Li cell and switch, that’s the whole circuit. Don’t think they could cook so fast unless there was some serious thermal upset.

’Though now with continuous-38A cells…

Turning blue means that solder under led is bad and melting at low temperatures. Try to reflow same xpg3 with better solder and flux, worked for me couple times even with DTP boards and XHP70…

You think they could work again?

I did led reflow only one time before, so no experience with that and no tools for that.

I am 99% sure they will come back to life…
Probaj nemas sta da izgubis :beer:

So runtime is less than 30 mins on high? And only 13 kcd?

NikolaS
I will try :slight_smile:

blueb8llz
That’s what manual says. I have no way of measuring it.

The emitter board is said to be aluminium and heat transfer to the leds' thermal pad is thus also crippled. It would be wise to start measuring tailcap currents with less than fully charged batteries and work your way up from there to observe current ramp up as cell voltage is increased.

As it is, lower discharge cells may work better in this torch.

Cheers

You were right, reflow helped and leds are working good.

Only problem I have is it died again, but if I press on led with my finger it works when pressing.

I have to clean the board and replace solder and I think it will be ok. This time I only heated it as it was.

You welcome :sunglasses:

Just clean all remaining solder with copper wire after removing led, and some 1000 grit sandpaper will clean underneath led remains with just slight moving without any pressure. Applying good flux and quality solder will solve the problem for good…

NikolaS

I tried today several times and there is always at least one led not working good.
All of them are working now, but 2 are on only about 50% brightness.

Not gonna bother with it anymore.
I have asked Sofin for replacement MCPCB or I will somehow put 3 DTP boards in with XP-L HI.

Just ordered this light and three of these: http://kaidomain.com/p/S026300.Nichia-219C-Neutral-White-4000K-CRI92-LED-Emitter-with-KDLIGHT-3535-16-16mm-x-1_5mm-DTP-Copper-MCPCB
Since I have these LEDs as a triple in my S2+ and I am loving it, I hoipe to get a very nice High-CRI trower (i.e. more throw than that triple S2+ ;)) with this combination.

Sorry to hear that,hope you will end up with best solution. I have xpl-hi on the way, hopefully next week I will have a chance to test out that driver since Sofirn claims 4.5Amp and 1300+ lumens.
I will do a short review also

I am on the same boat, NikolaS. I am waiting for a C8T on its way in the slow boat.

Cheers :-)

Good thing it was free or I would be really mad :slight_smile:

Vf of LEDs in parallel doesn’t alter.

They don’t “avalanche”.

But if badly mis-matched, the lowest Vf one will take the majority current.

Or badly flowed onto a poor MCPCB, the one with the weakest thermal path will overheat soonest.

If one turns blue, it is getting far far too hot, and will never be quite the same again. DTP copper MCPCB is essential at these current levels, standard aluminium one hopeless, we learned this here years ago. It seems Sofirn have some catching up to do.

Yes I know the Vf of any given led doesn't changes because of parallel arrangement, Tom Tom. Leds in parallel will, however, share the load current, each one its own piece of the cake and thus their Vf only raises up to the corresponding shared current value (just ⅓ in this case for well matched emitters), which of course is going to be a lower value than that of most more poweful single emitters at the full current.

Cheers

PCB have big mass 30mmx1,5 and most obviously haven’t been heated properly resulting bad joints. At 6 Amp each led is taking 2 Amp which is not too much trouble for XP-G3 but results are more than bad…