Just acquired an American Gulbransen 7L in reasonable condition. (Page 102, Golden Age.) Here's a view of the interior, and a close-up of the chassis ID. Does anyone have the circuit for this radio, please? I can't find it in the NZVRS circuits.
It arrived with three knobs like this. Would these be the original 1936 knobs?
The radio works quite well, so most of the restoration effort will probably go into the cabinet and grille cloth. Would a cabinet from this period have been french-polished?
Most US made Gulbransens I have seen in NZ have wooden push-on knobs with three ribbed sections around the outside. Circuit can be found at Nostalgia Air www.nostalgiaair.org/Resources/488/M0023488.htm The cabinet would have originally been nitro-cellulose lacquer.
Thanks very much, Daniel. Nostalgia Air is certainly a useful reference, but unfortunately in this case they only have dial data for the 7L, and not the actual circuit. Any ideas for an alternative source?
Would a modern polyurethane spray varnish be an acceptable alternative to nitrocellulose? Maybe semi-gloss?
Just spotted a small number of borer holes, so the cabinet is coming off today for treatment. I don’t have a big enough freezer to use Steve’s technique!
Sorry for the bad link. Usually Nostalgia Air is the place to go for US radio circuits. After some investigation it looks like the 7L circuit does not appear in any of the Riders Manuals, and 7L’s seem quite scarce in the US hence the lack of online info. Fortunately I have a service manual in hard copy which I have emailed to you.
I have used spray polyurethane in the past, but didn’t like the result, too plastic and hard to get a consistent finish. I tend to avoid refinishing all but the very worst cabinets. I clean them down with the green Swafega hand cleaner and a coarse cloth, wipe dry with an old towel and then polish up with Antiquax furniture polish.
If I have to refinish I mostly scrape off the old lacquer with a hard steel scraper, sand with fine sandpaper then refinish using polyurethane diluted 50% with turps and wiped on with a piece of old t-shirt. 2 or sometimes three coats works well, no brush marks, no overspray and no runs.
Many thanks, Daniel - very interesting! I tend to agree with you about the polyurethane. In the case of this 7L, though, it looks as if it has been relacquered some time in the past, and not very well, so it might need to be stripped. I guess though it would be possible to try your technique first and see what it looks like. If it doesn’t work I could always strip it later. Your t-shirt technique sounds like the ‘fadding’ technique that french polishers use.
I didn’t receive the manual: do you have my email address?