That's some schematic. Sure can tell it was drawn before standards were set.
http://www.nostalgiaair.org/PagesByModel/914/M0040914.pdf
Use 10 mf @ 450 volts for the 8 mf's and 22 mf @ 450 volts for 16 mf. Connect all negatives to chassis ground. Disconnect the original but leave it mounted. Replacements should have plenty of room under the chassis.
Norm
:Hi,I have written before about another radio and I want to thank all who answered for their help.I have a model 72 Zenith that plays,but has a fairly loud hum.I was going to replace the big canister capacitors(leaving them attached to the frame)and was wondering what capacitance and voltage? Should I use 8 or 16 microfarad and should the voltage be 450 or 600?Also upon replacement,should I connect the positive to the wire and the negative to the frame?Any help would be greatly appreciated.Thanks in advance,Ira.
I cannot find a schematic for a 72.
But generally... you should follow the values you find on the old caps.
So if you have 2 caps in one metal or cardboard can and the values are shown as 8uf@450v and 16uf@450vdc
Then you should replace them with similar values but if you can't find those particular values you can use a more common value as long as it's close and larger.
So you could use a 10uf to replace the 8uf and a 20uf or 22uf to replace the 16uf
Be sure to use at least the same rated voltage or higher... i.e. 450vdc should be replaced by nothing less than 450vdc ..so anything higher.. 500vdc or 600vdc is fine.
You should completely disconnect the old cap. Do not simply bridge a new one across the old one.
If the old one has the negative side of the can connected to the metal chassis you can also connect both negs of the new caps to the chassis too. However be very careful to see if the old cap is in fact insulated from the chassis by a phenolic washer.
If it is ...then the new caps should follow the same connection to neg as the old can... but be certain that the positive side of the old can has no connections whatsoever to anything anymore.