The biggest problem was the three tuning caps. Their frames were made of pot metal, which had that pot-metal disease - causing physical warpage and impossible clashing between the rotors and stators. I wasted a day thinking I might be able to salvage the tuners by trying to straighten, align, and buttering up with J-B Weld. It was a lost cause. I finally replaced the tuners with ones that I pulled out of a junker, and they fit pretty easily.
Then I wasted a least a day trying to get the thing to play. The proper voltages were at the sockets and all the coils were OK. I finally discovered that the brass wipers on the tube sockets were dirty and making poor contact with the tube pins, particularly in the RF section - how stupid of me to not have cleaned them as a matter of course. Once I got the sockets cleaned, the set took off like gangbusters.
The only remaining chore is repairing one of the two brass tuning bands that gang together the three tuners. The band had broken in two.
Except for being battery powered, this set is similar to an Atwater Kent Model 40 - with a metal cake-box case that is smaller than an AK 40's box. It uses all '01A tubes, although the schematic allows substituting a 71A for the 2nd audio tube, and running the B+ for that tube up to 135V rather than 90V. But an '01A provides plenty of power, so the more expensive '71A is unnecessary.
You did great finding a tuner that works. So much pot metal usually can't do anything with these Crosley's. Can't find a substitute tuner to fit.
Keep it, I am sure not many are saved due to pot metal.
Bands usually break from expansion of the pot metal pulley. You can use Atwater Kent belts.
Norm
:This is a 6-tube, battery-powered TRF, c. 1928.
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:The biggest problem was the three tuning caps. Their frames were made of pot metal, which had that pot-metal disease - causing physical warpage and impossible clashing between the rotors and stators. I wasted a day thinking I might be able to salvage the tuners by trying to straighten, align, and buttering up with J-B Weld. It was a lost cause. I finally replaced the tuners with ones that I pulled out of a junker, and they fit pretty easily.
:
:Then I wasted a least a day trying to get the thing to play. The proper voltages were at the sockets and all the coils were OK. I finally discovered that the brass wipers on the tube sockets were dirty and making poor contact with the tube pins, particularly in the RF section - how stupid of me to not have cleaned them as a matter of course. Once I got the sockets cleaned, the set took off like gangbusters.
:
:The only remaining chore is repairing one of the two brass tuning bands that gang together the three tuners. The band had broken in two.
:
:Except for being battery powered, this set is similar to an Atwater Kent Model 40 - with a metal cake-box case that is smaller than an AK 40's box. It uses all '01A tubes, although the schematic allows substituting a 71A for the 2nd audio tube, and running the B+ for that tube up to 135V rather than 90V. But an '01A provides plenty of power, so the more expensive '71A is unnecessary.
I've read that the rot occurs from the inside out, so it's impossible to prevent. I believe that is true. Parts that have a relatively large cross section seem to suffer the most destructive expansion and warping.
A single, monolithic casting may have a large, central member and several, smaller appendages; it's the larger members that seem to become most damaged, while smaller members look almost new. I assume that smaller members are better able to relieve the internal stresses.
My theory is that if a pot-metal part just breaks in two, repairing it with J-P Weld might very well work successfully. The two smaller pieces may be able to handle the internal stresses.
Speaking of J-B Weld, is this product any more than a garden-variety, 2-part epoxy? They seem to imply, but don't state explicitly, that it's got microscopic steel particles in it - and the color reinforces this implication. But they also say that the cured material does not conduct electricity.
I also have learned something about polishing brass. This radio has a large, nice brass escutheon that was very badly tarnished. Brasso didn't faze it. So, I tried a generous application of Naval Jelly and let it soak for about 20 minutes (thanks, Norm). After washing off the Naval Jelly, I then used Brasso, and it looks as good as new.
J-B weld is an epoxy. It has special stuff in it. I don't know if it actually has steel or if they just imply that in the name of one of the tubes. If it does have any metal in it, it won't conduct electricity anyway, because of the plastic material which surrounds each metal particle. It is doubtful that a lot ofmetal particles will contact eachother all the way through the mass even if some manage to. Think ferite (spelling?) rod, and you'll have the idea. The ferite rods have the iron randomly oriented, and the powder is held together with something...not sure what. J-B weld reminds me of bakelite, which is also an epoxy. Pretty much any two (or more) part item which cures by catalytic action (chemical action) is an epoxy. You could almost say that concrete is an epoxy. I'm not sure if it technically is or not. It chemically cures, though, and gives off heat.
Thomas