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Old 10th Mar 2019, 9:14 am   #1
Wilf123
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Default Beolit 500 tuning fault

Hi all
This is my first post and Iím completely new to vintage radio.
I have recently purchased a Beloit 500 FM radio from eBay. Itís the shelf style 5 button model no tuning dial.
Condition is reasonable cosmetically and when powered up there is life in it. Iíve opened it up cleaned the switches with contact cleaner etc. The easy bits. The volume works fine. Tuning though is the issue. Iíve fitted the correct 22.5v battery and it does pick up a signal but itís jumbled. Sounds like itís getting multiple frequencies at the same time.
Iím an aerospace design engineer by trade an therefore technically minded but no experience with electronics. My usual hobby is clock restoration but Iím looking to start with vintage radio too. I obviously have a lot to learn.
Can anyone give me any pointers to get me started on the Beloit? Iíd hate to damage it out of ignorance.
Cheers all
Wilf
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Old 10th Mar 2019, 10:13 am   #2
paulsherwin
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Default Re: Beloit 500 tuning fault

Do you mean a B&O Beolit 500?

https://www.beoworld.org/prod_details.asp?pid=836
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Old 10th Mar 2019, 10:21 am   #3
ronbryan
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Default Re: Beloit 500 tuning fault

It''s the earlier one, from 1966. 22.5V and 7.5V batteries.

https://www.radiomuseum.org/r/bang_beolit_500.html

Ron
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Old 10th Mar 2019, 12:30 pm   #4
60 oldjohn
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Default Re: Beloit 500 tuning fault

First time I have heard of a radio / intercom. What's it like using it as an intercom ? any break through of radio stations ?


John.
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Old 11th Mar 2019, 2:41 pm   #5
tri-comp
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Default Re: Beolit 500 tuning fault

Wilf,

For some very strange reason I seem to have the complete service manual for this Beolit.
It's in Danish (Surprise, surprise) but it's yours if you want a PDF-copy.
Just PM me with your e-mail address.
File is ~3,7Mb i size.

Rgds,

/Torben
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Old 12th Mar 2019, 5:42 pm   #6
Studio263
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Default Re: Beloit 500 tuning fault

Quote:
Originally Posted by 60 oldjohn View Post
First time I have heard of a radio / intercom. What's it like using it as an intercom ? any break through of radio stations ?
The intercom function works by connecting the loudspeaker sockets of two of the sets together, it isn't an RF link. It uses the loudspeaker as a microphone when transmitting, which works pretty well. If you only need a 'push to talk' function at one end then an ordinary loudspeaker will work for the other station, we had one set up like this for some time, good fun.

Most tuning problems resolve to a flat 22.5V battery. These are hard to get now but two 12V car alarm batteries in series work just as well. These are cheap and easily available, solder on flying leads and then solder these to the battery contacts. It will probably last the life of your interest in the set like this.

For those who don't know, the 'on' switch is pressing one of the preset station buttons. The 'off' switch is pushing the volume control down a little, an unlabelled function. Great for those who want to defend obscene broadcasts, "people know where the off switch on their radios is". Not if they have a Beolit 500 they don't!

This was the first radio with electronic varicap tuning for FM, 1966 model year. They added it to the Beovision 1400 TV set a few years later, another 'first' for the mighty B&O.
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Old 13th Mar 2019, 5:20 pm   #7
Wilf123
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Default Re: Beolit 500 tuning fault

Thanks for all the replies. Can anyone guide me on the Varicap tuning and how faults might manifest themselves?
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Old 14th Mar 2019, 2:11 pm   #8
SteveCG
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Default Re: Beolit 500 tuning fault

I don't know this model, however I've found that jumbled tuning can happen when the preset pots have developed (mechanically) poor contacts between the wiper and the tracks. Also, is there a voltage regulator circuit designed to provide a constant voltage to the preset pots? This will use a zener diode that may have gone electrically noisy; hence the tuning voltage would be jumping around giving a jumbled receiving frequency operation.
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