Scott 312D hum

[911s55]

I have a very nice believed to be original Scott 312D tuner that has started do develop a 60 cycle hum on start up that goes away within the first 5 minutes or so. It also will cease when I switch to mono, but not consistently, but does always clear up.

I have had it for a few years, not serviced during my ownership, yet. It performs well, zero drift, sounds and receives great just this recent issue. Obviously a trip to a tech is in order, any clues as to what these symptoms indicate and is there any immediate danger in continuing casual use?

My uneducated guesstimation says caps in the power supply or related to the FM multiplex, or?

Thanks folks.

 

[amptramp]

If the hum is actually 60 Hz, it could be heater to cathode leakage in a tube or one open rectifier diode.

 

[KentTeffeteller]

The 312D is not a tube tuner, is Solid State. The electrolytics in mine were bad, and it needed some alignment to perform best. Replace the electrolytics, they're past prime on this tuner.