IIRC Philco repair bench had a good table of block cap part numbers with an explanation of their contents (my go-to resource), but I just checked and I can't find it, along with a good portion of their site...What happened to them?
Quote:
Originally Posted by ZenithDude88
I didn't say he couldn't I was just saying if it were me (and since I don't have much experience with pre-war radios mostly post war radios) I would of passed on it because from what I saw in the picture the speaker was trashed to the point that there was nothing left of it say for 2 pieces hanging on by a thread so to speak (and repairing that speaker or sourcing a "new" one can be quite difficult especially trying to source another speaker like it had in there originally.
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There are many places that specialize in re-coning speakers. If the voice and field (if not PM type) coils have continuity, that is a good option.
If the speaker is beyond professional help there is always a way to spec a new one (of any vintage including brand new). The most important thing is geometry and diameter. If it is the same mounting size you don't have to modify the cabinet, and there are ways to make it work electrically. Getting the same voice coil impedance is important to reusing the same audio output transformer, but there are ways around that. Speaker impedance matching transformers exist, and one can spec new audio output transformers by knowing/finding the plate impedance of the original and getting one that matches that to the impedance of the new speaker. If the original had a field coil you can use a PM type speaker and substitute the field coil in the power supply circuit with a power resistor or preferably a choke of similar impedance....Sure it is part of the power supply filter circuit, but there is a lot of fudge factor in those designs, and if you've got some spare parts to play with it can be arrived at easily with experimentation. Knowing theory of operation, and associated maths helps the process greatly and helps ensure it will work best the first try.
It is good to know your skill level, but challenging yourself, learning new techniques, and approaching things by not assuming things are impossible/impractical will help you grow...Thirst for knowledge helps too.
...That said if you told me you were captinclock back under a new user name, I'd believe you...Your writing style/personality feels rather similar.
