BUSH 22" LY2211WCW LCD TV DVD COMBI distorted sound

[quak]

hi, just repaired psu on this troublesome set only to find sound on digital channels are low distorted and hissy,, all other functions are fine with good sound and pic thru  dvd analogue and all other connections, any ideas anybody, avi board type is MST9E19B 0091801317V2.0 any help would be apreciated, cheers quak