08-14-2015, 07:15 PM
I believe that's where the original electrolytic filter capacitors were:
http://antiqueradio.org/art/Philco90Back.jpg
Since those very likely went bad many many decades ago someone may have removed them and tacked on replacements under the chassis.
http://antiqueradio.org/art/Philco90Back.jpg
Since those very likely went bad many many decades ago someone may have removed them and tacked on replacements under the chassis.