i was using yahama pre - power amplifer setup so i decided to bring it to States. Here when i switched it on the pre amplifier started going to "protection" mode. after living with this problem for some days i decided to vaccum clean inside it, and then i used hair dyer inside on circuit for good 15 minutes.
after my small operation . pre amp is working fine.. no more "protection " modes . touchwood.
according to my hypothesis the pre amp picked up humidy inside lugguage compartment inside aeroplane.. and heat from hair dyer removed it.
hopefully this writeup will be helpful for anyone who leaves electronics in humid area.