stewart - warner 300

[wa2ise]

Originally Posted by stusnyder

it seems like one of the transformers is not getting power to it.

Sometimes the rosin in the solder used back then was a bit corrosive on the fine copper wire. Sometimes careful resoldering to bridge the break might fix it.

[stusnyder]

Originally Posted by wa2ise

Sometimes the rosin in the solder used back then was a bit corrosive on the fine copper wire. Sometimes careful resoldering to bridge the break might fix it.

Worked on it tonight, I do have power in and out both transformers. Checked out everything else and did not find anything obvious. 2 capacitors in entire radio. No value listed on them or in schematic. Anyone know what value are these?

[leadlike]

Caps are typically 1 or 2 mfd, rated for a couple hundred volts DC. On these 20s radios, typically you'll find the interstage transformers open. There are replacements available-I believe AES sells just the bobbin and windings so you can use parts from your old tf to keep things looking original. You can also bypass your tfs with some common value caps and resistors. I think the Philco repair website has a how to on that.

[stusnyder]

I did some checking on it tonight, it seems like one transformer is open.

[wa2ise]

Somewheres on the web I saw an article on using of all things a ringer from an old Ma Bell telephone as a replacement for such transformers.

[stusnyder]

Originally Posted by wa2ise

Somewheres on the web I saw an article on using of all things a ringer from an old Ma Bell telephone as a replacement for such transformers.

Antique radios have replacment transformers. I'll have to order one.

[leadlike]

Here are the notes on replacing the interstage transformer. On a radio similar to yours, I used modification C:

http://www.philcoradio.com/tech/audio.htm

It kind of reminds me-while most radios of this period are set up like yours, with the last two stages transformer coupled, I have an American Bosch radio from the same period that is entirely resistance coupled. Maybe Wa2ise can explain the advantages/disadavantages of these circuits.