Sony STR-AV-1020 Receiver Hum problem

[Mike Macari]

I have a Sony receiver that has developed a hum (approx. 160hz)
which varies from day to day (due to temperature?), from barely
audible to absolutely annoying. It is not a grounding or ground
loop problem! I have isolated the unit from every connection
and away from all other radiating equipment; just a receiver
and a speaker. No matter which input is selected, the hum is
there! Also, the volume control has no impact on how loud the
hum is.
I recall related postings in the past which complained about
similar problems, but I don't remember seeing any fixes.
The unit is 3 old and beyond it's warranty. So before I go
to my last resort of sending it back to Sony for repair$,
has anyone had a similar problem fixed?
Any information is appreciated.

Mike Macari
GDC Technology Center
(203) 574-1118 X6146

[Scott Leapman]

I used to have a 1020 also, and I had the same problem. You are partially right
in your assessment of the problem. It is most likely the same one that I had
that WAS grounding relation... not external, though, internal. That model (and
possibly others) of Sony receiver uses the chassis as a central ground for all
the circuit boards in the thing. Each circuit board has grounding pads around
the screw mounting holes in their corners. I found that the humming went away
after tightening all the mounting screws on each circuit board. The first time
this happened the receiver was under warranty, and that's what the service tech
told me that he did. I had to repeat the procedure several other times over the
2 years that I owned the receiver, but it worked every time. Try it, it might
work for you too (and save you big repair $$s)! HTH!

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