So i found the problem on mine the eprom is bad or erased the adress bus is ok but there is nothing on the data bus apart a little background sound on certain keys and preset. I will buy an eprom reader next month and try to read it see if i can save a part of its program. On the dp20-25-40 the eprom only contain the samples if i have understand it correctly, so i'm optimistic that if i find out how they have written and arranged the samples in the program i could at worst replace the original samples by any others.
For the moment it's my midi Controller on ableton, just for that it's way better feeling than any others cheap midi controller.
By the way if someone have the eprom data saved or can copy one, please can you send it to me !