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PostPosted: 09 Nov 2013, 01:04 
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Joined: 18 Feb 2010, 10:52
Posts: 86
Location: Menifee, California U.S.A.
Having trouble locating a replacement part for my tube radio.
Can anyone please steer me in the right direction to obtain a replacement.
The tone control fades out at the 10 o' clock position.
Switch, volume control and tone control ganged in one unit on the Magnavox FM-45 tube radio.
Thanks,
Robbie7


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PostPosted: 09 Nov 2013, 08:45 
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Joined: 04 Jun 2008, 20:59
Posts: 4030
Location: Arizona, USA
It looks like a fairly standard style control. The very first thing I would try is use some "DeOxit" on it. About 990% of the time this will fix the problem. If not a replacement is in order. The difficulty is that it seems to have what they called a "loudness compensation" tap on the side (the lug opposite the three in a row). First you need to measure the resistance from the end pins on one or the other section (call them 1 and 3). That will determine the "value" of the control. It will be a log or audio taper so no need to do anything with pin 2. Typical values for the control would be from about 500K ohms to 1Meg ohms. I have seen some in the 100K and 250K range though. My first try would be to contact Antique Electronic Supply (partsandmore.com on the web). They stock many vintage parts. You can of course not use the "loudness compensation" tap and just leave the components loose (or remove them). This will cause no harm. Indeed the feature has not been used as far as I can tell for many years. It acts like a tone control at low volume settings to boost either the bass or treble or both to make the sound "fuller". You can do the same with tone controls as I expect your unit has them. It is far easier to get a replacement control without the tap.

Good listening
Bruce

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PostPosted: 14 Nov 2013, 10:03 
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Joined: 18 Feb 2010, 10:52
Posts: 86
Location: Menifee, California U.S.A.
Thank you,
Bruce. I will try the fix first. If that does not work I will try to find a replacement.


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