[Jeffhs]

Benjamin,

I looked at the pic of the back of your Stromberg just now and saw what looks like an octal plug and socket, with a rather long cable going back to the speaker. This leads me to believe your set has an electrostatic (as opposed to permanent magnet or PM) speaker system. (I once had a Magnavox AM/FM receiver with such an arrangement.) The electrostatic speakers used a field coil which was also part of the power supply (as a choke), and were common in console radios of the '30s and '40s. This also leads me to believe your SC was made some time during that era, as PM speakers did not appear in radios until the late '40s-early '50s.

If you have (or have access to) a Variac, which is a variable-voltage autotransformer, I would use it between your set and the AC line if you have doubts as to whether the radio works. Start at zero, then bring up the voltage very slowly, using the control on the front of the Variac, watching for any signs of short circuits, e. g. smoke, sparks, etc. If you can increase the voltage to 120 VAC without problems, you can continue with your testing. Lacking a Variac, you can power up the radio through a 100-watt bulb, which will act as a current limiter. If the bulb glows dimly when you plug the set in and turn it on, the power supply is likely OK. If, however, the bulb lights brightly (or immediately burns out with a bright white flash) as soon as you turn the radio on or plug it in, there is a short which must be corrected before further testing is conducted. I have a 1951 Zenith radio with a pilot light on the front of the cabinet; this lamp will burn out immediately if the filter cap or rectifier tube is shorted (or if the filter is deformed for any reason) when the set is turned on. (Note as well that if the radio is operated with an open pilot light, the filaments of the tubes will be overloaded, as the pilot light normally takes up part of the filament voltage.)

Many AC/DC radios which had pilot lights wired across the rectifier tube (35W4, 35Z5, etc.) would exhibit similar behavior if the tube or the filter cap were shorted as well. Another tipoff to a shorted filter capacitor is if your radio blows a fuse or trips a circuit breaker on the house circuits as soon as it is turned on (or as soon as you plug it in); the reason is that the filter cap is wired directly across the AC line. If the filter shorts, it will put a direct short across the line which, of course, will blow the fuse or kick out the breaker immediately (the radio does not have to be turned on).

In a set this old, I would replace the capacitors on general principles, as there are certainly a few leaky or even shorted ones under the chassis.


Hope this helps.

Best of luck and very kind regards,