I dont know what the problem is, I think something is broken (short circuit).
If I turn the LED‘s of, blue is on. If i turn it on, everything works (can change the colours etc), but blue is always on. Only green or red not possible.
If I had to guess, which I am guessing, it looks like a MOSFET drives each LED output. My guess is either a shorted MOSFET or a MODFET constantly gated on for some reason. Bottom of the image on the right above the terminals. Those 3 components look to be the MOSFETS driving the RG & B leds.
Thank you for your answer!
I tested with a multimeter and I think you are right;
I want to buy new mosfet, but I have no Idea which one.
Looked at ebay and found the name „sot-23“. But n-channel or p-channel, 4,3 A or 5A? My LED-Stripe is 10m with 2 inputs.
In the past I played around with some 5050 LED strips which were common anode 12 volt. Since they were common anode I used an N Channel MOSFET on a breadboard. I used FQP30N06L MOSFETs which are just every day logic level mosfets but were in a TO220 case, not surface mount. This is what my setup was.
You don't need much as to current and inthe above, while it worked fine, it was severe overkill.