Beolit 500 tuning fault - UK Vintage Radio Repair and Restoration Discussion Forum

Wilf123 · 10th Mar 2019, 9:14 am

Hi all
This is my first post and I’m completely new to vintage radio.
I have recently purchased a Beloit 500 FM radio from eBay. It’s the shelf style 5 button model no tuning dial.
Condition is reasonable cosmetically and when powered up there is life in it. I’ve opened it up cleaned the switches with contact cleaner etc. The easy bits. The volume works fine. Tuning though is the issue. I’ve fitted the correct 22.5v battery and it does pick up a signal but it’s jumbled. Sounds like it’s getting multiple frequencies at the same time.
I’m an aerospace design engineer by trade an therefore technically minded but no experience with electronics. My usual hobby is clock restoration but I’m 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? I’d hate to damage it out of ignorance.
Cheers all
Wilf

paulsherwin · 10th Mar 2019, 10:13 am

Do you mean a B&O Beolit 500?

https://www.beoworld.org/prod_details.asp?pid=836

ronbryan · 10th Mar 2019, 10:21 am

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

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

Ron

60 oldjohn · 10th Mar 2019, 12:30 pm

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.

tri-comp · 11th Mar 2019, 2:41 pm

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

Studio263 · 12th Mar 2019, 5:42 pm

Quote:

Originally Posted by 60 oldjohn

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.

Wilf123 · 13th Mar 2019, 5:20 pm

Thanks for all the replies. Can anyone guide me on the Varicap tuning and how faults might manifest themselves?

SteveCG · 14th Mar 2019, 2:11 pm

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.

10th Mar 2019, 9:14 am	#1
Wilf123 Retired Dormant Member Join Date: Mar 2019 Location: Manchester, UK. Posts: 2	Beolit 500 tuning fault Hi all This is my first post and I’m completely new to vintage radio. I have recently purchased a Beloit 500 FM radio from eBay. It’s the shelf style 5 button model no tuning dial. Condition is reasonable cosmetically and when powered up there is life in it. I’ve opened it up cleaned the switches with contact cleaner etc. The easy bits. The volume works fine. Tuning though is the issue. I’ve fitted the correct 22.5v battery and it does pick up a signal but it’s jumbled. Sounds like it’s getting multiple frequencies at the same time. I’m an aerospace design engineer by trade an therefore technically minded but no experience with electronics. My usual hobby is clock restoration but I’m 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? I’d hate to damage it out of ignorance. Cheers all Wilf

10th Mar 2019, 10:13 am	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Beloit 500 tuning fault Do you mean a B&O Beolit 500? https://www.beoworld.org/prod_details.asp?pid=836

10th Mar 2019, 10:21 am	#3
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,960	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

10th Mar 2019, 12:30 pm	#4
60 oldjohn Dekatron Join Date: Dec 2004 Location: East Yorkshire, UK. Posts: 3,987	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.

11th Mar 2019, 2:41 pm	#5
tri-comp Heptode Join Date: Oct 2008 Location: Aalborg, Denmark Posts: 903	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

13th Mar 2019, 5:20 pm	#7
Wilf123 Retired Dormant Member Join Date: Mar 2019 Location: Manchester, UK. Posts: 2	Re: Beolit 500 tuning fault Thanks for all the replies. Can anyone guide me on the Varicap tuning and how faults might manifest themselves?

14th Mar 2019, 2:11 pm	#8
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	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.