I have a wurlitzer 2300s wich has an anoying loud hum when a record is
playing. The hum does not change in loudness when I turn up (or down) the
wolume of the amplifier. It is stil there when I pull out the first tubes of
the amplifier.
I suspected the capacitor on the power unit so i took ik out and tested the
thing, it seemed to be o.k.
I measured the frequency of the humming sound, it is 100 Hz. The power we
use overher is 50Hz (in NL), so I should think it is the 'ripple' on the DC
(280Volts?) that produces the humming sound, but I'm not sure about this.
Can it also be a faulty rectifier tube? Or anything else?

Can anyone give me a clou how to fix this?

Thank You for Your help.

Johan
(excuse me for any bad spelling, I'm Dutch)