Home » Restoration » Kolster-Brandes BR40 Restoration: Part 1

Kolster-Brandes BR40 Restoration: Part 1

Over Christmas I had a notion to investigate some vintage radios and how much money I’d expect to pay for one, with a view to restoring it. I wasn’t looking for any brand or set in particular so I took to the internet to see what I could find. After browsing for an hour or so I found a Kolster-Brandes BR40 – released in 1947 – being sold quite close to where I live, so I did a little research on the radio before making an offer. The seller accepted my offer of €35 and I collected it this week, and thus began my very first radio restoration project.

While trying to find information on the radio I noticed that there were very few photographs of it available online. So few, in fact, that I didn’t really have any idea how big the radio was going to be. With that in mind I committed myself to taking plenty of photos of the radio during the restoration process as well as documenting the work I carry out. Hopefully that information will make this series a useful resource to any owners or restorers of the BR40 in future.

BR40 with Coke bottle for scale

BR40 with Coke bottle for scale

I decided early on that a fully authentic restoration isn’t necessary for me at the moment. If I can do work on it to keep it authentic that’s great, but if that authenticity comes at large expense or impractically difficult work, I don’t intend to stress out over it and will just do what I can. This means that when I replace components I will most likely replace them with their modern counterparts, unless original parts are readily and inexpensively available. My main goal is to have a working radio receiver that looks good, which I think is what most original owners of this model would have cared most about.

I thought about various aspects of the project before collecting the set, and my first concern was the condition of the valves in the radio. While they can last a long time, the valves in this set were possibly almost 70 years old, assuming they hadn’t been replaced since. Ideally, all the valves would be in working order and I wouldn’t have to go looking for expensive replacements. At worst, some wouldn’t work and they’d have to be replaced anyway. When I got the radio home I opened up the back panel only to find that five valves were missing! It looks like I’d have to get replacements after all; oh well! Luckily, RadioMuseum.org has an extremely useful information page for the BR40 including a list of the valves used and their equivalents. Using this information, I took to the eBay to source some valves. I’ve now ordered three valves from Germany for the set which are identical to the original valves needed, with the exception of having a metal case, rather than a glass case. I ordered all three from the same seller, and they came to just under €26 including postage.

My next concern was replacing capacitors, but that is a fairly straightforward job. I found this page on AntiqueRadio.org very informative. At the moment, my general plan of action for the capacitors is:

  • Replace all paper capacitors
  • Replace electrolytic capacitors only if they look bad (bulged, corroded, etc.)
  • Leave mica capacitors alone

Paper capacitors are the most likely to be damaged in a radio this old, whereas mica are the least likely. Of course, I will inspect all the capacitors in the set and come to a final decision on a per-case basis.

Upon opening the radio the most obvious issue was dirt and dust. Before doing any work the radio will have to be cleaned out, not only to keep it looking well, but to prevent debris getting into any soldering I may need to do. The metal chassis also shows some rusting, but not an unmanageable amount. I think most of this can be removed and the chassis recoated in new paint. The case for the large paper capacitor, however, is badly rusted: I will remove this altogether and find or make some sort of replacement cover.

Back panel removed

Back panel removed. Note the badly rusted capacitor cover and empty valve sockets.

A cursory look over the outward-facing electronics seems to show that they’re in relatively good order, otherwise. The rotors of the trimming capacitors on the left look fine, and the electrolytic capacitor on the right looks good, too. I’m particularly happy with the condition of the large tuning capacitor: even if this restoration project works out badly, that tuning capacitor will be very valuable in future DIY projects or fetch a few quid if sold.

I stuck my phone camera in underneath the gap at the bottom of the chassis to get a quick look at the condition of the electronics inside. I was quite pleased as everything appears to be in better condition that the outer part.

Part of the inside of the chassis.

Part of the inside of the chassis.

Aside from a little dust everything looks clean and the solder joints look good. Even the metal casing is mostly rust-free. I will check everything in more detail when I delve in, but by the looks of things I shouldn’t have much trouble at all with the electronics. The service manual for the BR40 is available for download here and contains a list of all the components used as well as a schematic diagram of the circuitry. The radio itself also has a short service sheet attached to the inside of the cabinet, detailing how to attach speakers and gramophones and what valves should be used.

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Operation and service sheet.

Moving away from the interior it was time to inspect the cabinet of the radio. As you can see from the first photo in the post it’s in pretty good order overall, but needs some work. It looks like someone tried to paint the cabinet at some point and put on too much paint, so that there are some drip marks on it (this could have been how the BR40 was originally produced, but I think that’s unlikely). I will remove this paint with sandpaper and apply a stain. I’m thinking something like a dark chestnut colour would be nice and would also show the grain of the wood. I’ll decide for definite once the paint is removed. Following this, I will apply a lacquer or polyurethane to give it a nice shine and to protect the wood. Polyurethane is far from authentic, but again, authenticity is not my main goal with this project.

The top of the cabinet shows some evidence of woodworm, with several small holes dotted around it. I’m not sure what to do with these just yet, or if I’ll do anything at all. The holes may be old but I’d rather not take any risks, and might apply some sort of insecticide to the inside just in case. I’ll see.

Drip marks on the paint job.

Drip marks on the paint job.

You can also see above that the white border around the speaker is scratched, revealing the black material underneath. This will be easily fixed, as I have an air compressor and spraypaint gun that will be ideal for applying a new layer of paint to this. The white border around the control panel at the top of the photo is in worse condition. It’s actually slightly warped in one place so I might replace this part completely.

The control panel is in good condition and should need not much more than a cleaning. The Kolster-Brandes badge is worn a bit, but I’ve seen resin KB badges available: if I don’t touch it up myself I can easily replace it. The tuning knob (or maybe the large tuning capacitor) squeaks a bit when turned, and this can probably be fixed with some switch cleaner and a lubricant. The waveband selector seems a little stiff when turning, but I expect this is mostly due to a buildup of dust and dirt in the inner mechanics. The moving dial indicators work perfectly fine and move freely and consistently. You’ll notice that the dials have different colours: behind these are bulbs which light up the front panel when the set is turned on. The circular window above the badge is above one of the glass valves inside the radio, so it glows when powered up. I’m particularly looking forward to seeing the radio lit up!

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Band and tuning knobs, with the shortwave band dials. The KB badge is to the left of the image.

The speaker cloth on the front of the set will be replaced if it can’t be cleaned. Again, cloth like this is readily available and comes in a huge variety of different styles. Hopefully I can find one (almost) exactly the same.

Grille cloth and damaged border.

Grille cloth and damaged border.

I think that’s everything to be covered in the first inspection of the Kolster-Bandes BR40. The radio does require a good bit of work, but as everything seems to be in reasonably good quality I don’t think it will be an impossible job and should be relatively straightforward with enough patience and care. I’m really looking forward to working on the project, so please do check back again for the next part of the series. Feel free to let me know your thoughts in the comments!

To finish up, here are a few more photos and details of the BR40.

Back panel company logo.

Back panel company logo.

KB badge on the control panel.

KB badge on the control panel.

 

Paper capacitor box.

Paper capacitor box.

Price tag of the BR40

Price tag on the back panel. A bargain at £2.30! :)

Input voltage selector.

Input voltage selector. Seems to be jammed at 225V (conveniently!).

More of the internal electronics under the chassis case.

More of the internal electronics under the chassis case.

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Kolster-Brandes logo on the chassis next to voltage selector. Serial number 01369, I think.

External antenna socket, with internal antenna cable plugged in as directed.

External antenna socket, with internal antenna cable plugged in as directed.

 

MW and LW tuning dial, with tone and volume controls.

MW and LW tuning dial, with tone and volume controls.

 

A frayed power cable that will be replaced.

A frayed power cable that will be replaced.

 

A valve case with a valve inside.

A valve case with a valve (6Q7G) inside.

Tuning capacitor

Tuning capacitor.

Trimming capacitors.

Trimming capacitors.

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