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38-39 Vibrator Power Supply Replacement
#3

Somewhere I read about reconditioning a mechanical vibrator by connecting it to the power line in series with a 40 Watt light bulb. Usually what happens is that the hash capacitor fails and the contacts inside the vibrator burn up, sometimes you can repair it, and sometimes not, but don't even think about replacing the vibrator with a SS substitute without changing that capacitor first. This set uses a synchronous vibrator and those were troublesome devices, they not only produce a pseudo AC for the vibrator transformer but rectify the output as well. If you want to scrap the vibrator supply and run it off the AC power line, building a power supply shouldn't be too hard, though given that the set uses battery tubes 6 volts at 2 amps sounds high. The set has 6 tubes so they no doubt wired the filaments in a series-parallel arrangement, the schematic states 6 volts at 1.4 amps, and that includes the vibrator supply current as well. I would just treat this set like a 1930s farm battery radio without the vibrator supply and build a supply accordingly, half of the B+ supply is already in the radio, parts #45, 15B, and 15C, right after the vibrator supply.
Regards
Arran

http://www.nostalgiaair.org/pagesbymodel...013249.pdf


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RE: 38-39 Vibrator Power Supply Replacement - by Arran - 07-01-2017, 10:44 PM



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