[Dave]

"FrankMeng" wrote in message
...
I bought a receiver of Onkyo TX-SR 606.
Everthing works fine, except the receiver becomes very hot if the
power is on.
Even there is no signal to the receiver, as long as the power is on, I
can't put my hand on it for more than half a second because the box
burns my hand.
Is this normal for Onkyo TX-SR 606?
Will the overheating cause a problem after a while (several months, or
years)?

Hot enough to burn you is too hot. The thing that kills electronics is
heat. Most components are rated for use for a specified number of hours
(mean-time between failure or MTBF) at 85C... there are some rated at 105C
but consumer-grade equipment manufacturers are generally too cheap to use
them.

I have no knowledge of this particular amp, but I'd guess the bias of at
least one channel is way off if the amp runs that hot at idle (no signal).
Biasing of the output transistors sets the idle current... on some amps it's
adjustable with a trimpot on the amp PCB (one per channel) and on some amps
it's fixed and can only be changed by swapping out a resistor with one of a
different value.

Dave