Silvertone Model 4733

[sslevinski]

Hi! We recently acquired a Silvertone Transistor Organ, Model 4733, apparently originally from Sears...? It was free and playable, but there is something wrong with the F card. It plays the same, high-pitched F across all octaves. Does anyone know what might be wrong or where I could find a replacement?

Our daughter is 16 and has taken piano lessons for years with the dream of learning to play the organ. Now that we have one, she is ecstatic, but is having a hard time finding music to play that is not in the key of F! Or has too many Fs in it LOL

Any advice would be much appreciated - thanks!

[jbird604]

I'm pretty sure those organs were made for Sears by Thomas. And of course Thomas has been out of business for 40 years or so. There used to be some support for these models through Organ Service Corp of Marengo Indiana, but they have recently closed shop, best I hear.

That doesn't mean that a diligent tech couldn't fix the organ. What you have is almost certainly a failure of the first "divider" stage on the F generator board. The way those organs worked was to have a master oscillator for each of the 12 notes of the scale, with the oscillator tuned to the highest pitch of that note. For example, the "F" generator board's master oscillator outputs a frequency equivalent to the highest "F" pitch on your organ. Then, to produce the lower octaves of "F" notes, the board has a series of "dividers" that simply divide the incoming frequency by two, thus producing the octave below. This goes on in a string of dividers long enough to produce all the "F" notes required on that organ.

Depending on the year of manufacture, your generators could have individual transistors for each divider stage, or they could have some kind of integrated circuit or component package. A tech with the proper service manual could probably find the bad part and probably find a source for it, whichever type it is. But there's not much you can do on your own. You could take out the "F" board and carefully inspect it, looking for a part that is obviously burned or damaged in some way. A transistor or capacitor could have one leg that got corroded and broke loose from the board, and that would be an easy thing to fix.

Failures of these old divider circuits are fortunately rare, but when one fails, you just lose all the notes of a particular letter name below the failed divider. The good news (but not for you) is that this organ has lasted about 30 or 40 years longer than the maker thought it would!