I second that. And, if it is using an external power supply, see if you have another one (check voltage and polarity).
 
Wilko

I tried all that and the piano is a home digital piano so it's to heavy to move.

Dimmer in the wall right next to the home digital piano?
 
Compact fluorescent light in piano lamp?
 
Computer display monitor sitting on top of home digital piano?

No
 
Yes but the piano been doing this sense i've got 
 
Nope.

At no point have you told us what this piano is? 
Does it have a wall wart or a direct AC plug. 
Also you were not clear about if there is a hum with headphones or audio output or both or if it's a Yamaha it only will have headphone out. so? 

Its a home digital piano the cabinet version. Williams symphony digital piano.
Its a  three prong Ac power cord I tried to replace it with another one but solve nothing.
Yes everything I hooked up to the headphone or audio outs there's hum.
 

Thanks for answering marcus.
 
Just to be clear I want to ask again.
 
Q: Compact fluorescent light in piano lamp?
A: Yes but the piano been doing this sense i've got 
 
Is there a compact fluorescent lamp nearby? If so unplug the fixture and see if it helps a little. Even if it only helps a little it will suggest what the problem may be.
 
 
It seems like you have done all the trouble shooting you can. It's possible a technician could trace down a specific problem and fix it... I doubt it will be an efficient or inexpensive process. If it were me I might trace the power supply looking for ineffective AC coupling leaving AC on the DC rails. It may be faster to simply start replacing filter caps, which is what a lot of techs do to save time. Even so, it's not really an efficient process, it's more like a brute force attempt to make a problem go away. It might help.
 
It can be, as you suggest a bad wire or solder connection... that's a search and repair process that is even less efficient. I think that factory wiring is a lot more consistent these days then back when the "bad solder" connection earned its reputation as a likely candidate.
 
Finally, I'd want to consider how loud the hum is. If you are paying attention you'll find low level noise in all sorts of consumer grade gear. If the piano sound is substantially louder than the hum, and effectively drowns it out for all but recording purposes, then it may just be inherent to the design and quality level of that product. Only you, and people who can listen to it first hand, can make that assessment.
 
Good luck!
 
best regards,
mike
 

Possibly made in China? Seems like it's a simple matter of using inexpensive circuit design to keep the price down. I'm not surprised after reading a few reviews. The old term you get what you pay for applies. The problem with under priced gear is you end up buying the good stuff in the end anyhow. This has been my observation and why I avoid certain Brands.

Yeah fluorescent lights and dimmers can certainly generate stray electrical signals that will be picked up by amplifiers. I was under the impression (maybe false) that this had all been eliminated as a potential problem. You could simply turn off all the lights and run a three prong extension cord from another wall outlet that comes from another breaker. If you still have the noise then that pretty much isolates it, unless there are grounding issues concerning the entire house.
 
I have only used the Privia 150. I use it to track 88 key piano parts. I was having some issues with the sustain pedal tracking. There seemed to be a delay from when I pushed the pedal to when the midi was recorded. I haven't used it since I replaced the pedal with a better one..it might have been a problem with the pedal.