yamaha psr 530 annoying noise is heard?

by malin
(Sri Lanka)

Hi, I've owned a PSR 530 since, like, 2001, but nowadays when it is turned on and idle the speakers make a really annoying noise (sounds a bit like a series of high pitched clicks/beeps) and I can't do anything but wait for it to disappear (which takes around 3-10 seconds at the most). Can somebody please help me? Also, possible, may I know where I can get a guide to disassemble it so I can clean the inside if the problem happens to be caused by dust built up over the years? All help is greatly appreciated.