Manufacturer: RCA Victor, Montreal, Canada
Model: 531D
Approximate Date Of Manufacture: 1949
Type: 5-tube Superheterodyne AC/DC AM broadcast band radio
Tube lineup: 12SA7, 12SK7, 12SQ7, 35L6GT, 35Z5GT
Status: working, restored
Where purchased: eBay, April 2004
One of the dial lamps was not working, the back was loose, and it looks like someone extended or modified the wires to the loop antenna on back; I don't know why. There was a small crack on the bottom of the case, taped with glass tape some time ago. The front knobs were reversed, the knob with the dot is the band-switch knob. It has a phono input on the back. A somewhat unusual design feature is that the phono input cuts off the radio input when a jack is inserted.
Restoration consisted mainly of a good cleaning inside and out, gluing the crack with cyanoacrylate glue, replacing the dial lamp, and polishing the case. There is a date stamp on the chassis of Nov 25 1949, indicating its date of manufacture. I did not replace any capacitors as they were of a moulded type rather than wax (I have heard some reports these fail just like the wax ones). Some of the tubes had been replaced at some time as they were different brands: 2 RCA, 2 Westinghouse, and 1 Addison. I cleaned up some of the wiring to the speaker and antenna as some connections were just twisted together, not soldered.
Where the front of the chassis joined the plastic tuning dial there was a layer of red wax that appears to have been intended to make a seal so the light from the dial lamps would cleanly illuminate the dial. The wax is soft and quite messy.
Even in the basement with no external antenna it picked up a few stations on shortwave as well as broadcast, so all bands appear to be working well.
I purchased an original RCA schematic from JustRadios.com and also later found it on my CD of RCC manuals. The schematics indicated there was also a model 531F which was identical except with slightly different frequency ranges (maybe for a different market from Canada but it was still 117V).
Some time later (January 2005) I finished restoration. I replaced all the "black beauty" paper caps with new ones. Looking at my original notes I see that at the time I got the radio I didn't realize that these caps were prone to failure, since they are not wax covered. I also replaced the electrolytic cap with three new ones, stuffing them inside the original can. I replaced the wires to the antenna coil, as they had been clumsily repaired by someone before. I replaced the line cord, which was getting brittle. I performed a complete alignment on all three bands, which made a dramatic improvement in performance on shortwave. In doing the alignment I realized that the dial pointer was incorrectly hooked up to the dial cord and was moving backwards, so I fixed that as well.
