American Bosch 855L - schematics & hints to replace shorted rotary switch disc

[david winter]

Hi,

I recently got this very nice and quite big radio. It has 10 tubes, an amazing dial with a number of push-buttons and a motor for automatic search.

I'm looking for two things: obviously a schematic, but also how to replace one of the rotary switch disks which became conductive after burning, and now arcs permanently (B+ vs ground more or less).

I'm putting a picture of the switch here. I would consider buying a spare disc or the womplete switch assembly. In the worst case, I'd buy the chassis but only without tubes, transformers, variable cap and dial assemblies. Else shipping might be too expensive.

I'm also thinking about keeping the outer (static) part of the switch, extract the small metal pieces of the inner (burnt) part and try to locate this small part, which shouldn't be that hard as it's pretty classic if you don't look at the contacts themselves.

Any ideas ? Thanks !

David Winter

[Reece]

You should be able to fix that. You have a picture so that will guide you in reinstallation. Take out the center rotor part of the switch and scrape all the burned part off with a knife. If there's any burning that has penetrated the phenolic that needs to come out with more scraping or a Dremel-type tool. Contacts can be cleaned up and if any rivets are loose, carefully restaked. Then slow-drying epoxy, which tends to be stronger than the quick stuff, can be used to strengthen the part.

[jonboy55]

I went searching for a schematic for the Bosch 855L and can't find any mention of it in any book.

Are you sure that is the correct model number? Could the chassis have a different model number?

Just thinking out loud.

[akent36]

Sometimes an American Bosch radio schematic can be found as a Westinghouse.