Yes ..
At low currents (200-250 mA ) ,and happened couple times by now ,with 3-4 leds only in the string ..
Rest works fine ....
Now ...First time that happened ,I unsoldered the leds ,wiped out excess solder and resoldered them ,without adding new solder paste ...
Problem disappeared ...
Flickering does not have any repetitive pattern or "rythm " ,neither is periodical ....
It just flickers like an EQ led ....Kinda like crazy morse signaling ...
I'm sure it's tiny bridges ...
Leds that do that ,when I test them with polymeter ,reading reads Resistance(or Voltage drop ,I'm not sure ) and does not light the led ...
Normal placed leds ,light up (at really low current ,given by the polymeter in "continuity test " settting ...)..
You know what ?
The whole secret of success,regarding kitchen hot-plating leds , is the applied solder paste thickness/quantity ..
Following a reflow soldering profile of a led ,with kitchen stove plate and playing back-forth with it's temperature knob ,might seem the tricky part ....
Well ..Ain't ...In fact ,it becomes ridiculously easy ,if you do it 2-3 times ....Seriously ....
If too much solder paste applied ,at these tiny pad distances /measures ,then bridges form ....
I've to train more at applying solder paste ....
An ordinary toothpick ,can do wonders ,"cleaning off " excess paste between the traces ..
It is way boring ,though ....
As for a solder paste S.Steel sheet stencil ...
Dunno ..Sounds Way complicated (needs laser cutter,for sure ) for that sizes ...
Why I haven't ordered some "spare " Oslons ? Why ?
How stupid one man can be ?
Edit : Until I'll find some money ( I'm totally broke by now .... ) to order some spare Oslons ...
(Guod ,it is your fault !!!! Now ,I'm totally addicted to Osram .Games Over .Osram Forever ! Osram Rules !
Best leds ever ! (at least ,for our "beloved purposes" ...)
I'm thinking of making a "dummy load "from two "humble" 1N4007 diodes (Vf =1.something ,if I remember correctly ? Or it is .5 V ? ...
OOps ..Will the diodes handle the 700mA current ? >...??? ..I think not ...Just a jumper then ...Or a 1206 res ,maybe ? )...
At least make rest of the string work back again .....
I need it for the grow to continue ....
( Although two leds on the string might be short-circuited by bridges ....Do not light up & are not burned/fried ..Weird ...
Both of them I tried to rework them with Weller solder tip ...Might I short -circuited them ? ..Might be ....
.............
......Learning the hard way ...The right way ......)