Home » Restoration » Kolster-Brandes BR40 Restoration: Part 2

Kolster-Brandes BR40 Restoration: Part 2

I finally got round to disassembling the BR40 to inspect the electronics inside. The main thing I wanted to check at first was the mains transformer, to see what condition it was in and if I could find a make and model number so I could get a schematic for it. The outward-facing part of the transformer looked to be in bad condition so I will likely need to find a replacement for it.

Mains transformer

Mains transformer

Unfortunately the transformer is covered in wax so if there’s anything on the casing I can’t see it. The three coloured dots are presumably some sort of information: the other transformer in the chassis has three dots (different colours) which is used in the manual to determine what resistors should be used, depending on the colours.

Overall, the electronics look to be in good condition, with the exception of the paper and wax capacitors. I’m not too worried about these though, as I will replace them all. In the ring of capacitors shown below, one of them towards the left is in pretty bad shape, showing just how susceptible this type of capacitor is to degradation.

Paper capacitors

Paper capacitors

While doing all this it was time to think about what to do with the radio cabinet. As I mentioned in the last post, the paint job on it looked a bit sloppy with a few thick drips, as though it were repainted at one point (of course, maybe it was always like that). My initial plan of action was to strip off that paint to reveal the wood and its grain underneath. I’d like to stain the wood in maybe a dark walnut or a mahogany colour, then lacquer the cabinet.

To remove the paint, I used an electric hand sander with #80 grit sandpaper. The result is nice and smooth, but I will still use a higher grit paper (maybe #120) to give the wood a ‘once over’ before staining.

I didn’t remove the white border pieces while sanding. The upper borders where the dials are placed were tacked into the cabinet. I didn’t have the tools handy to remove them safely without breaking them. The lower border with the speaker grille is connected to a panel inside the cabinet that mounts the speaker. That panel is, in turn, screwed to the cabinet; screwed very tightly! Again, the screwdrivers I had to hand couldn’t tackle a couple of the well-rusted screws, so I decided to leave them alone for now so that I wouldn’t damage the unit.

Here are a few photos.

Before. Original paintwork in daylight.

Before. Original paintwork in daylight.

A comparison of the sanded front with unsanded side panel

A comparison of the sanded front with unsanded side panel

Detail of one of the side panels. Note how it's actually two pieces of wood joined together

Detail of one of the side panels. Note how it’s actually two pieces of wood joined together. Also note the woodworm holes.

After. A "naked radio" with the paint stripped off.

After. A “naked radio” with the paint stripped off.

Next up is to sort out the woodworm holes to see how I can fill them (any suggestions?), and also to work on the white border pieces. I think for those I’ll give them a light sanding to smooth out any rough edges or bumps, and then spraypaint them with an ivory coloured paint.

There are plenty of sources online for grille cloth, so that won’t be a problem to get. What may be a problem will be finding a cloth that matches the original. Anyone know what type of cloth it is or where I can get BR40 replacement cloth? If I don’t find an exact one, I’ll get something as close to it as I can. Either way, I will wash the original so I can check it’s colour: I’m not sure that those particular brown hues are reflective of what it looked like in the radio’s earlier days!

As for the electronics, I’ll look back over the BR40’s service manual for a list of capacitors and order them in. I’ll probably clean up the chassis as I’m working on replacing the components.

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