[davemc]

I am working on a model 58 (I think - like the 57/58 schematic in Riders). It is all original - has not been touched. The filter capacitor is a 30-2013 A.  It has three lugs in a triangle: black paint at 12:00, Green at 8:00, and Red at 4:00. The problem is that the all original wiring does NOT match the schematics in Riders or Philcoradio.com.  In my radio the Red marked lug goes to the rectifier (filter input), and the Blue (or Green) lug to B+ (filter output). That is the opposite of the Change documentation for Capacitor 30.  I believe this has been discussed before, but I was unable to find an answer. 

Should the filter input capacitor be 8mfd or 4mfd?  The schematic says 4mfd (blue), but in my radio it is 8mfd (red).

[Kekoa]

I can't answer your specific question, but I can tell you that the Riders schematic for my 53-960 had a very similar problem.  The values and schematic for one of the electrolytic capacitors simply did not match what was in my (all original) radio.  So, I bought the SAMs schematic and it was spot on.  It perfectly matched what I was seeing in my radio.

I think mistakes are probably not uncommon, and cross checking two or more schematics from different sources may be your best bet. Anyway, good luck with it, and let us know what you find out!

[David]

Hope this helps I was  unable to add just the single page sch.http://makearadio.com/beitmans/index.php   Look under 0AD-1938.  David

[davemc]

Thanks. The Beitman schematic (Philco 57) seems to be the same as the Riders/Nostalgia Air (Philco 57/58 ) as well as the schematic at Philcoradio.com, in that the input filter capacitor is 4mfd(blue) and the output filter(red) is 8mfd. My radio, and at least one other one mentioned on the Phorum is just the opposite. Most other radios I have seen that have filter chokes or speaker fields used as chokes have the larger value capacitor as the INPUT filter or both capacitors have the same value. For example, the Zenith 9S30 uses a 16mfd input capacitor and 4mfd output filter.

All the schematics references, IMHO are drawn rather weirdly in the power supply area. And the Riders schematic was originally missing a connection!

Unless I get definitive information, I will likely restuff using 10mfd/450 volts for BOTH filter capacitors.

[David]

80.pdf Size: 108.13 KB  Downloads: 164

10Mfd would be max. Would guess what they used had more to do with the physical size and cost. David