mitsubishi vs-60609 humming sound

first i would like to say this is a great site ...with your siteshelp i found my convergence ic was bad ..and that it could be fixed rather easliy ...but i lack soldering skills so i decided to have a local shop fix it......they did and the picture is now working fine but when its cold and you first turn it on you can hear a slight humming sound from the speakers..when it heats up it goes away ...the tech said maybe a noise filter is going bad and tracing it down would be hard to do...the noise did not start till ic was replaced ..any ideas????