08-21-2015, 11:02 AM
Philco didn't make this easy when they used the same schematic to show different chassis with different tube counts, with their dotted lines and crossed out connections, especially if you aren't an old hand at reading schematics. After 1940 they didn't do this as much.
I've always found it helpful to make careful diagrams before I change a component or wire, using schematic symbols for resistors and capacitors rather than drawing their shapes, and labeling the values next to them. I draw the wires in with colored pencil, using dotted colored lines for wires with tracers. Before I solder any connection I double check my diagram against the schematic. The diagrams take time, but they give me more confidence that I can put things back the way they were. Slow and steady wins the race. For me, it's more fun and less frustrating that way.
But I still occasionally blow it, like the time I scratched my head a long time when I left off the resistor that supplies B+ to the mixer tube on a 40-190, then did the same darn thing on a 40-150 a few months later!
Except for old repairs, your radio is probably wired correctly, so even if the schematic is confusing, you can always fall back on putting things together as they were, and you'll be right almost all the time.
Your radio is a pretty complicated one to learn on. It does get easier!
I've always found it helpful to make careful diagrams before I change a component or wire, using schematic symbols for resistors and capacitors rather than drawing their shapes, and labeling the values next to them. I draw the wires in with colored pencil, using dotted colored lines for wires with tracers. Before I solder any connection I double check my diagram against the schematic. The diagrams take time, but they give me more confidence that I can put things back the way they were. Slow and steady wins the race. For me, it's more fun and less frustrating that way.
But I still occasionally blow it, like the time I scratched my head a long time when I left off the resistor that supplies B+ to the mixer tube on a 40-190, then did the same darn thing on a 40-150 a few months later!
Except for old repairs, your radio is probably wired correctly, so even if the schematic is confusing, you can always fall back on putting things together as they were, and you'll be right almost all the time.
Your radio is a pretty complicated one to learn on. It does get easier!
John Honeycutt
