Re-Routing Filter Capacitors Problem

FrankB wrote:

 I thought I would post this so you can understand just how critical lead dressing can be.

Frank makes a very important point which must be learned by those new to the hobby. Lead dress can be very important in many circuits.

Back in the 80's I was rebuilding an RCA console for my boss for his office.

I removed the multi-section old screw base filter (non-insulated), and mounted the the replacements under the chassis. All were properly routed and properly grounded. Finished the total rebuild and turned the set on. (The entire can was aluminum, including the screw base, which was the ground).

 What the heck! The radio had a horrible hum when I was finished. Just horrible! Bad new stock filters?? Nope. 

After some  agony I finally discovered that in this specific radio needed the filter caps mounted on top of the chassis, shielded by the filter cap can.
 I gutted the old filter cap and mounted them all in it. Hooked the 3 filter sections up as they had been, and the hum was totally gone. The radio worked properly. 

I can only surmise that in this case, the lead routing on the filters under the chassis introduced some odd sort of hum into the wiring that went away when the can was re-stuffed & mounted on top of the chassis. 

This is the only case of this I have ever run into in all my years of servicing.

 I thought I would post this so you can understand just how critical lead dressing can be. I am still spooked as just how sensitive this set was to wire routing issues.