10-05-2010, 09:16 AM
Hold the phone, guys.
The tone control only has the usual three terminals. Some Philco schematics, such as the 40-180, draw it as a pot with a 6 meg element, a break, then a 400K element in the same unit. Others draw it as a regular pot, 6 meg. I think the early ones (such as used in some 1940 models) were built with a separation in the element; these will check infinite resistance on your ohmmeter. I think Philco later began to use 6 meg pots with no break in the elements. (Thinking as I type here.)
The 6 meg pots work very well as a tone control, when the associated components are of the correct values. I've modified a couple of my sets (my "Super" 71 and "Super" 89) to use this type of circuit. I really like how it works.
Check your schematic. You will find that tone control only has three terminals - the two end terminals plus the wiper arm, no more.
The tone control only has the usual three terminals. Some Philco schematics, such as the 40-180, draw it as a pot with a 6 meg element, a break, then a 400K element in the same unit. Others draw it as a regular pot, 6 meg. I think the early ones (such as used in some 1940 models) were built with a separation in the element; these will check infinite resistance on your ohmmeter. I think Philco later began to use 6 meg pots with no break in the elements. (Thinking as I type here.)
The 6 meg pots work very well as a tone control, when the associated components are of the correct values. I've modified a couple of my sets (my "Super" 71 and "Super" 89) to use this type of circuit. I really like how it works.
Check your schematic. You will find that tone control only has three terminals - the two end terminals plus the wiper arm, no more.
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Ron Ramirez
Ferdinand IN
