10-12-2024, 10:12 AM
Before a rewire, I always make it a habit of tracing every connection and cross referencing the schematic. I will then recreate the schematic in full using CAD software (I like kiCAD, because it is free). I actually missed one tie dot myself while I was doing this for my 49-906, in the IF section. Those little dots are pesky!
In my recreated schematics, I will also add a semicircle to indicate one trace passing over top of another WITHOUT a connected node. Common practice is to do this to the horizontal trace. It’s a lot of work, but I hope it helps out the next guy to be working on my sets! I also create revisions and update parts that need to be replaced. I once needed to replace an output transformer with the closest model I could find from Hammond, for instance. Another time I needed to select a different value for a plate resistor because I couldn’t find the value called out on the Philco schematic. I got one within 10% tolerance, and marked it up on my schematic.
I realize that this is all probably overkill, but I find that it really helps me when I may go months at a time before needing to go back to the same schematic. A computerized schematic is also much more legible.
In my recreated schematics, I will also add a semicircle to indicate one trace passing over top of another WITHOUT a connected node. Common practice is to do this to the horizontal trace. It’s a lot of work, but I hope it helps out the next guy to be working on my sets! I also create revisions and update parts that need to be replaced. I once needed to replace an output transformer with the closest model I could find from Hammond, for instance. Another time I needed to select a different value for a plate resistor because I couldn’t find the value called out on the Philco schematic. I got one within 10% tolerance, and marked it up on my schematic.
I realize that this is all probably overkill, but I find that it really helps me when I may go months at a time before needing to go back to the same schematic. A computerized schematic is also much more legible.
Joseph
Philco 46-480
Philco 49-906