[R-390] thanks

[2002tii]

Tim wrote:

>Line filter caps have this tendency to begin failing on line voltage 
>peaks. So what you get is a 60Hz or 120Hz noise coming from the 
>capacitor as the layers begin to arc over. If it's not in a metal 
>can, it is very very common to see wax or fumes coming from a wax 
>capacitor at this point, and sometimes you can see little sparks 
>inside if the arc-over is happening near the surface. It is also 
>actually audible, either hearing a 60Hz/120Hz buzz or a curdling 
>noise as wax melts or vaporizes. In a metal box there's much less to 
>see but I can believe that a 60 Hz or 120Hz buzz could be heard.

This is a plausible source of mechanical buzzing, but in this case it 
may be inconsistent with the reported finding of 60 volts on the 
ungrounded chassis.  Unless all four capacitors were failing in 
exactly the same manner at exactly the same rate (which is highly 
unlikely), one would expect that the voltage divider formed by the 
caps would become unbalanced and there would be a different, and 
likely varying, voltage on the ungrounded chassis.

Best regards,

Don