C20 hum?

[ferninando]

I have a job upcomming to trak down some hum on a friends C20 preamp.
I have not as yet seen it.
Does anyone have any previous experience with the C20 and hum?
Specific things to look at.?
Any info is much appreciated.
thanks.

 

[ron-c]

You will need to rebuild the power supply on a preamp this old.
Also check for rear chassis grounds on all of the in and output jacks.

thanks,
Ron-C

 

[ferninando]

O whoppie, it figures.