Hello, i am back with good news,i buy this keyboard as defectiv with (no Power no sound) i dont know the history, i have seen only the cable under the DM Board was connected crooked, but on the boards i have not seen desoldering it was all original, maybe the predecessor has connected a external powersupply with + and - reversed
i have buy some used spare parts DM and AM Board (with no sound on the speaker), and i have installed the bought DM Board in my piano and my piano is playing again, after this succes i have inspected the AM Board and i replaced two capacitors from the AM Board an tested this and he is playing with sound again.
Thanks for the support an this page from Howme and mrchips, i have learn many thinks for repairing DIY