1931 Airline 62-141- Need Advice

[Winky Dink]

I've had this on the bench for five months. Recently got a legible schematic (Did you know that Rider's has an early edition of Volume II? The schematic in the later edition for this model is terrible.) I'm ready to rebuild the paper caps, but I'm puzzled about modifications not shown on the schematic. Please understand that I'm still trying to learn "radio stuff," so if I misspeak it's because I don't know any better, and corrections are welcome.

I have good photos and diagrams in a Picasaweb album.
http://picasaweb.google.com/coldrb/A...eat=directlink

In the modified schematic (direct link below) I moved components to give me a better visual picture and added arbitrary component and terminal labels to correspond to my photos.
Modified schematic:
http://picasaweb.google.com/lh/photo...eat=directlink

Three questions:
Does my markup of the modified schematic make sense?
Should I restore by the original schematic or try to duplicate the modifications I see?
Who were they making 25-cycle radios for?

Thanks for your help.

[Reece]

Hi, I like your very neat redraw showing all the caps in the box. It looks to me as if somebody outboarded the 8mfd cap (in red) and cut the wire to the one internal to the box. That, of course, would just be replaced with a good one in the box. You could use a 10 mfd. here.

The blue wire with "?" doesn't make any sense. In making that connection they would be bypassing the three-section dropping resistor and going straight to full B+. Maybe part of the resistor was open? I think I'd leave that off and after you recap and check all resistors, see how the set plays and check that plate voltages are within specs for each tube type.

25 cycle juice was available in certain areas, around Buffalo NY, for example. I recall an earlier thread about this radio: was it that there was a mining operation running 25 cycle and the adjacent town was fed from that? A 25 cycle transformer is beefier than one for 60 cycle so will just loaf along nice and cool at 60.

Was there some other point about the schematic that I missed?

[Winky Dink]

Thanks. I've been obsessed with the mysterious blue wire. Before I disassembled the condenser block I made notes, tags, and photos which confirm that the blue line enters block. And that wire is still attached to a capacitor. I put in the question mark because I've only identified that cap as C16 by default. Hopefully I'll find that I've made an error when I attempt to reconstruct the condenser block circuitry.

The radio is 60-cycle. I just added that question because when I was looking at early 1930s schematics I noticed that many manufacturers offered a 25-cycle twin model. Your memory of the Emmett, Idaho power is correct. The mining stopped before 1920, and I presume that's why the town got electrified so early.

Off the subject--I have to grin every time I read your "Perfection is hard to reach..." Twenty years ago, when we first got desktop computers and printers at work, we had to call IT frequently for malfunctions. When they put us "...on the schedule for next Thursday...," I'd have my secretary tell them, "Nevermind, the Colonel says he has a screwdriver and he can fix it." The screwdriver ploy always worked--IT would be in our office in ten minutes.