I was able to get this very nice radio working fairly well but it only plays on one speaker selection (speech). There are three buttons on the front (speech, music, and 'multisonic') which select different circuit configurations but the circuit is very complicated and I can't find anything wrong. I have cleaned the switches and they appear to be in good condition. Any comments would be appreciated. I have posted a detailed description and schematic on my Radio Club's website, www.njarc.org, under 'member to member' restoration help. Nick

Different tone configurations are achieved with different value condensers placed across the audio signal or in series with it. By placing a very small value condenser in series with the audio signal, bass notes are attenuated. By placing a very small condenser in parallel with the signal, treble notes are attenuated. Other amazing effects are achieved with various value resistors arranged in many ways. All of the above may take so many arrangements to achieve so many different tonal sounds, that they are too numerable to mention here.

Still, the general method of achieving the muted and pleasant "music" selection is caused by placing various condensers of certain values across the audio signal at various points. If these condensers have become shorted or leaky, they will kill the entire audio signal. A condenser never passes current and should never have a resistance value. Condensers charge up and hold charges. Different sizes allow different charges, and somewhat like the length of the arm on a pendulum, react differently to different frequencies. The alternating audio currents will charge up a condenser one way, and when they reverse, will charge it up the other way. Certain frequencies will charge it up in time with the frequencies, and will allow it to pass these frequencies. If hooked across the audio signal, it will cut out these frequencies, giving you the pleasant music tone selection. A condenser should charge up very rapidly on your resistance meter, and then your meter, set on its most sensitive setting (millions of ohms), should fall back to infinity and nothing less. To accurately test a condenser, remove one lead. Connect your meter across it. Do not touch both leads with your hands at the same time. The resistance in your hands will give false readings. The needle will jump up just a very tiny amount with values over .001 MFD, and not at all really with smaller values. It will fall back to infinity with a good condenser. It will linger up higher with a bad one. The needle must fall all the way to where it started for the condenser to be good.

Seeing as these condensers are likely shorted, you should check all other condensers in your radio to be sure that none are leaky in any way. Even small leakage in the millions of ohms will ruin the fidelity of your receiver.

If there are any resistors connected to any part of the tone control or any of its related components, check these as well for proper resistance. Remove one lead of the resistor in question.

Thomas.