Filter Block Capacitor Decoding
 

What's the best way to figure out which capacitors are electrolytic in the big block capacitors? I can't tell the values on some of these caps, and was wondering if someone might be able to shed some light, or a less washed out schematic. I believe that you can substitute a nonpolar cap for an electrolytic as long as the capacitance and voltage match right?
Attachment 198190

I had understood that the caps used in those early sets were all paper caps and not Electrolytics. I was never into those real early AC sets or with the ones with the potted capacitor blocks.
For replacements, you can use motor run ac type capacitors of the same or close value, which are non-polarized, as you stated. :thmbsp:

In Philcos the block caps were all paper type and I've seen them as big as 4uF IIRC. Some other makes used as big as 8uF papers (and probably bigger). You can replace them with lytics provided you get the polarity right...You can also get film caps the same value (sometimes even in the same part series/family as the ones you use for more normal paper cap values) in those values. Dieseljeeps method is valid and economical...Though smaller film caps make restuffing the originals easier if you choose that path.

Be careful of the exact wiring of the originals. There was practically no standardization then...You can encounter weird things like say 3 caps with a common lead in a can with 3 terminals where the common lead is connected to one terminal and one of the non-common ends of a cap ties to the can body and the polarity (if you choose to go the lytic route) is not obvious.

I used 630V brown drops for those. The generic Chinese metal film caps. Work great. Can secure them inside the old block with a dab of silicone, once you melt the tar or wax and clean them out.