how to ttl board with grbl

i all !
i have this board [www.banggood.com] for driving my 2500mw laser diode, but i can't get good ttl output from it.
I'm send signal fro arduino to the ttl + node (and if i test the arduino send 0 to 5 volt ok to this) but with 12v on this board in input, the outpu can only varry from 10.3v to 10.7v (0v in from arduino give : 10.3v and 5v give 10.7).
Can't understand why. i waiting that output voltage varry from 0 to almost 10/12v.....

Any one cane help me to resolve this or know this type of board ?

Thank's

... ask the seller or designer ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I also used to use this board and from what I can remember, there is a bug on it regarding polarity. The print on the PCB is wrong at the fan output or some other header. Better check twice and don't trust the printed polarity marks.

Thank's o_lampe. I'll check that.