cxb 3070 4000K veg light trouble

hallöchen !!
dear rollitupheads, long time stoners and diy freaks, long time lurker here.
first of all id like to thank all that cob pioneers on here, supra.. i read so many of your posts, and youre still coming up with new facts and numbers all the time.. incredible! sds, aleshh, robinn, mau5 and all the others i forgot to mention of course: thank you guys! thank you for sharing that powerful knowledge keep it on !

i never thought of having my own noob-asking-for-advice-thread, since i read for months now & hate all that thread-crashing spoonfeed bullshit people are starting up here. but for my 2nd cob build i need advice, bcause i cant figure it out myself, even tho i havent tried everything yet, maybe you have the answer before i have it myself.

my first build was a eco-nazi 16x 3590 .7A. surprisingly bright as f.ck. worked out without any problems.

for my second build, i wanted to create a dimmable modular veg light from 3070 BBs at 1.4A. (hlg-185h)
ordered everything from jerry. came here incredibly fast.
very happy about the arriving in like 2 days, i started drilling the first heatsinks, blablabla.

i noticed one cob had a little misformation. on one side the ceramic looked like something splintered off the edge, barely noticeable, but since its just the ceramics , i thought it was no problem. probably is not the problem, but i still mention it.
holes drilled'n'tapped i threw some thermal compound on the little crees, suprised by how fast this only 4LED lamp would be finished.
fcking ideal holders are a real pain imo, the chips are always dropping out of them..ahhh. could be another problem: one cob seems to not be in the exact position of the holder, its a little moveable, screwed on the sink, but the contacts should still touch.
all in all i made everything like with my first lamp, except for using different cable: first time i used stranded copper, this time its core. but i think its not copper. if it would be the cable, the cobs should still shine, and the cable would go up in smoke or something i think.
i also double and doubledouble checked the plus-minus-plus-minus series and its all correct.
its all connected right, but if i plug in the driver, nothing happens. checked it with a different driver. nothing happened.

im a little clueless now. my budget is over, so i have to wait for the multimeter of a friend.

what would be your diagnosis ?
or lets say it like this : what would be your way to find out, what the problem is ?


thanks for your time !
kindest regards
let it shine

re-check your chip-lok holders and ensure the COB's are well seated and do not move around at all. You should not be able to wiggle the holder around unless you are using thermal pads vice TIM paste. If you have movement, most likely your COB's are not seated well enough in the holders. The holders should hold them snug and no movement at all. I like the solderless approach with the chip-lok holders myself. easy to move them if you are using TIM pads attached to the COB itself. good luck. peace.

finally lit, thanks. it was about the holder. my fault.