Philips BX495U

...they said it couldn't be restored

1949 model from the land of windmills and wooden shoes

If you saw the Ambassador page, there's more to the story. When my buddy brought me the Ambassador for restoration, there was an old Philips set included in the deal. The Ambassador was a mess but I did it anyway. But the Philips was a hopeless case. Serious corrosion and generally bitchy radios to work on. I told him it was impossible. (I had worked on a similar old Philips for him recently and that one was still in memory.) Well, the thing sat around here for 3-4 years (I don't throw anything out) and probably got even worse in the salt air.
Some of us got to chatting about how bad does a set have to be before you toss it or scrap it for parts. In this case, scrapping for parts wasn't even a good option. It was a choice between the garbage can or forever taking up space here in the shack. With an air of dare, I decided what the heck. I'll dive into it for fun and see how far I get before I give up.

So, where do you start on something like this? A careful inspection showed that any major irreplaceable components like special switches, the tuning cap, audio out xfmr, etc were still usable. The main part that wasn't salvageable was the multivoltage switching scheme as seen in the 4th picture above. This is a 'universal' transformerless set that used a bunch of precision wirewound resistors in the voltage selection. All that wiring was on top the chassis, and if nothing else looked like a real safety hazard. No doubt a mouse or two had been cooked in that mess.
Moreover, the rectifier tube socket assembly itself was virtually corroded away and the tube shot. This being a universal model it was all mounted on a little bracket. Decision was made to just use a solid-state diode as the rectifier since nothing remained of the original and the tapped voltage scheme wasn't important for my use. This mod didn't leave any holes in the chassis.

Anyway, so the chassis was stripped and judicious notes taken for re-assembly. I had no schematic for this set but had one for a similar model 505 sent to me by a nice fella in The Netherlands. It was a little help but not much. I continued the emails and group pleas and finally Walter Haring in Switzerland found me a set of the data for a 491 model which was substantially closer to my circuit. As luck would have it, this was when I was pretty much done rebuilding the set but it answered some questions I still had pending.

Here's the chassis after an acid bath. People often ask about my procedure for undoing the ravages of corrosion. This was a very typical 'worst' case. I bathed it in muriatic acid for a while to eat away the majority of the rust. Rubber gloves and a wire brush doesn't hurt either! I forget how many times I went thru that but it eventually cleaned up. Next is a THOROUGH rinsing and stabilising any residual effects of the acid. Soaking in a pail of water/baking soda will generally neutralise any remaining acid. Next step was to use a phosphate 'rust remover' product to do its number on the bare metal. The phosphate solutions form a chemical bond to the bare metal to prevent further corrosion. Not always pretty but if the metal is good and clean then it does a nice job. After all that, I sprayed it with a clear spray. A few days later my hurriedness started showing up again. Some new crustiness started developing in corners, etc where I wasn't thorough in my process.
Lets go to Page Two and talk about Bakelite restoration