LarryO - I put in batteries and you were right no more hum, just a
quiet background whooosssh. Unlikely a unit like this gets much more
quiet than that!

If you, or anyone else can show me (in the correct photo I posted!)
which is the capacitor in question and what sort of replacement I
need, I'd greatly appreciate it.

thanks again for your help!!

Witnerd40
>
> Sounds like a power supply filter cap has gone away.
>
> The schematic shows a connection for an external AC adapter, which
> presumably outputs a DC voltage. That's where I would suspect the
> troublesome part to be. What happens when you run it on batteries
> alone w/o the AC adapter connected?
>
> Cheers,
> LarryO