need help panasonic tv TC-21PM50K model

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need anyone help
the problem is the system ic i change one time then bring back see for a week then the system ic broke down again ,,, location ic is IC601 Part list is 9590N48CJ ,,,, ok the main faulty of the tv is sound not sound like ssss...brrrrrrr like a bit of raining sound i think ,, but when change system ic ,, all sound ok..
i also check the voltage 5v and 8v ok .. not over voltage... so need sameone help out there
bye