usually its the bash chip the HC1011, there are two of them, try gently pushing on one of the top corners, if the noise goes away
then the chip is bad, it might work for a short period of time. I bought two replacements from JBL, look in this forum for the
number to call they cost about $25 each.
One is for the sub, the other is for the satellite speakers, the chip with the back facing outwards, where you can read the part number
is the one for the satellite speakers.