Android TV box suddenly lost sound only for AV connector, HDMI works fine.

Hi,

Need help. My android TV media box was working absolutely fine until suddenly the volume started reducing slowly and gone. This problem is only with AV connector (by the way cable is okay and CRT tv is also okay) . Tried with another TV via HDMI cable its working fine. I have no clue what might have happened. Recently I changed the power adaptor as with the old one the box was repeatedly rebooting.