I will forward your post to a collector in Australia. He may be able to help? .5 meg volume controls are common in the US. We could mail one if necessary.
Norm
:I'm attempting to fix a nice little console radio circa 1945 which I had previously re-capped and was working fine. I moved it to a new position, and it shorted out as the uneven surface and lack of base meant that one of the caps was pushed on to the main on-off switch which is combined with the volume control.A loud hum, a blown fuse and burnt-out on/off volume switch was the outcome! The pot seems to be unobtainable as it's rated 0.5M (doubles as "diode load", whatever that means!) and local electronics suppliers throw their hands in the air. I would be grateful for any advice as to how to find a replacement - after that's done,hopefully the rest will still be operable. BTW I'm in South Australia and have an interest in old audio equipment. Looking forward to all replies.
Hello Alan, That's a shame but you should be able to find a suitable replacement. The pot is a 0.5 Meg (500 k) log pot with a switch and is a standard item. It is the load for the diode detector and the audio signal is picked off it to feed to the audio stages. It's logarithmic which means that there's a large variation in resistance for a small rotation near the full volume setting and a small range near low volume (it's non linear). This gives an even control of volume over the full range; a linear control cramps the effect at low volume. I'll check out available supplies and get back to you. The set will work OK with any value from 0.25 to 1 Meg, although it's best to get the right one.
Don Black (Victoria, Aust.).