60 hz hum in KLH receiver

[MRMILSTAR]

I have an old KLH R3100 receiver which has recently developed a 60 hz hum in both speakers. It does it for all inputs. I have tried all sorts of grounding ideas to no avail. The amp has worked perfectly for about 10 years. It just recently developed the 60 hum. Are there any ideas as to the problem? My initial thought was that perhaps a capacitor has failed.

I could just buy another old used receiver on Craigslist for $50 but if this one can be easily repaired I would rather just fix this one.

[Twospoons]

That does sound like you have hum on an internal supply rail, rather than a grounding fault.  Can you get hold of a service manual? Can you scope the supply rails? At the very least run an eyeball over the internals to see is there's something obvious.

[petespaco]

Just my 2 cents, but I'd look for a bad electrolytic capacitor in the power supply.

[davekni]

I have an old KLH R3100 receiver which has recently developed a 60 hz hum in both speakers.

Have you scoped the hum to verify it is indeed 60Hz and not 120Hz?  And the waveform shape of the hum?  Presuming no half-wave rectification, bad electrolytic capacitors (most likely cause) would show up as 120Hz hum.  A failed rectifier diode should make 60Hz hum with a flat portion between dips or rises.  60Hz reasonably sine wave hum would suggest grounding.