strange behavior with an rgb led strip

hi arduino-comm,

i’ve a strange behavior with my rgb led strip. i tested following circuit:

My green LED is always active, like 100%. It’s just the green one, I constructed the circuit twice and getting the same issue again. The green LED lights up every time. The “-” from the external voltage is connected with all 3 transistors and with the GND from the arduino. When i set via Arduino the Color to red, it’s not red it’s Red/Green. Because the Green one still lights up. I tested the circuit once more and i see no error in it. Can anyone tell me, why my green led always lights up?

best wishes! per

maetho:
I tested the circuit once more and i see no error in it. Can anyone tell me, why my green led always lights up?

It is either a hardware problem (failed transistor) or a software problem (bad sketch).

Did you try swapping the Green transistor for one of the two known to work? Does the problem move with the transistor? If so, you have a failed transistor.

With the wires from the arduino out puts not hooked up does the led bar still light green? This may be a bad transistor.
Try hooking a 10K ohm pull down between the base and ground then leave the arduino outputs unhooked and power it on are they still on green?

Thank you for your fast answers!

@johnwasser:
It's definitely an hardware problem, since the software is working fine! Im not sure if it's the same transistor as earlier, because i just put them again. Would be kinda unlucky if i got the same one...

@drksam: Yes, i hadn't connect the wires to the arduino, it's still lighting green. I don't know from where the green LED get's the voltage. Looks like the transistor is broken, isn't it?

Because it's the same wiring to red/blue - so there's no difference.

K how about swapping the green transistor with another? And it may be possible that the transistors are a little small ( i dont know what kind you are using).

@drksam: I swaped the old one, he was broken!. It's working now! Thank you!

@johnwasser: Thank you too!

So the next question was what fried the transistor? Is it a suitably rated device
for the LED strip in question? If not you risk getting more failures in the future...