Hello Folks,
I am a new member. I used to collect radios when I had more time and room, but got rid of them all some time ago. I recently was given most of my father's unused radios and equipment and sold most of it, but I could not bear to get rid of this 41-250 that has been in his house longer than I've been alive by 10 years.
I am not much with electronics, so I will probably farm that out, but I do like the mechanics and the cabintry side of it, so I went after the cabinet first and it looks quite nice now. Most of the original finished was fine. I really needed a good cleaning and some touching up with Old English. I have a repro bezel and buttons on their way and it will look really good.
The chassis needed a good dusting and the faceplate support removed to get at the bare wire going to the illumination bulb. I rebuilt the bulb holder with a nylon washer and a new wire. Other than that, the wiring is almost pristine. To get at the other end of the wire, I had to flip the tuning coils and some other stuff out of the way. Running across the lot was a black wire that led to the phono socket (I think that's what it is, tell me if I'm wrong) in the center of the rear facing wall of the chassis (see pic). I tried unsoldering it but I pulled a bit too hard. The metal contact sleeve pulled off along with the wire.
Does anyone have luck fixing these, or do I need a new socket? Better yet, I would not a averse to replacing it with an RCA socket, if that is kosher. Can someone set me right?
(This post was last modified: 07-09-2015, 11:38 PM by MarkBardenwerper.)
That three-pin connector is for an external antenna. An adapter plugged into that socket which looked like an IF can with a switch on top and a screw terminal on the outside for the external longwire. It had a matching network inside (coil and caps).
Here are two links that should help explain things:
Thanks for the link to that fantastic restoration. It gives me the guts to try some of the electrical work myself. Those pics could not make it any easier to follow.
While mine is not in quite that bad shape, it still has something obviously wrong electrically and I hope that if I am patient, I will get to the bottom of it.
Hello Folks,
I have not done any work on the radio for a few days. I am concentrating on learning more before I proceed. I also collected a nice digital mutitester and some alligator leads. Something else nice has happened. I now own a B&K Model 700 tube tester. It is another hand me down from my father. Despite it's rather oxidized looking rivets and sockets, all of the Loktals from my radio have tested out well on it.
My trouble is in testing the 41's and the 84. They are not on the chart. Does anyone have a clue how to proceed?
I just took the cover off the transformer. It has the numbers, 32-8098M on it. It looks to be a replacement as the original used different holes and this one is located off to one side of the opening by three screws.
When I get repies on these questions, is it proper for me to move this conversation over to the restorations discussions, or should I stay here?
(07-15-2015, 11:26 PM)MarkBardenwerper Wrote: Finally got started with some tests today. I had to get a laptop set up at my work station with proper files running in the proper programs.
The first four tests (power transformer) are done and already I am literally aground.
1. 37.7 ohms
2. no reading
3. no reading
4. no reading
Now I know why the power cord was cut.
Looks as if I will be looking for a transformer right off the git go. Any suggestions?
The power cord was probably cut because the rubber insulation was rotten and flaking off, before you write off the transformer it would be best to double check things. The power transformers on those sets have a metal box covering them, the box should unscrew or unbolt from the chassis to expose the transformer itself, if it's burned out it will show with globs of melted wax and tar, not to mention stink. I find the infinite resistance readings suspect, there should be a primary winding and two secondary windings, one for tube heaters which is low resistance, and a high voltage winding which has three leads going to it and a resistance of maybe a few hundred ohms. That 37.7 ohm reading sounds like it may have been the primary winding.
To test the high voltage secondary pull the #84 tube, find out which pins connect to the plates, and stick your Ohm meter probes in the applicable holes. Then find the center tap for the H.V winding, usaully either connected to the chassis or to a large wire wound resistor and measure between each of the plate pins and the center tap, the resistances between the center tap and each plate pin should be close to equal (in truth you can measure between the chassis and those two points even with the resistor in series, if the resistor is still good that is) For the tube heater winding stick the probes in the two socket holes for the fat pins of either the #84 or the #41 tubes.
Regards
Arran
Hello Arran,
Thanks for the pointers. I went through everything again and things look different this time. Here we go:
36.7 ohms for the primary, should be 12
778 for secondary, should be 310
403 for the upper half, should be 160
375 for the lower, should be 150
.6 for the filament., is correct
They also don't match what I find in the diagram for my radio, which I downloaded.
Now, I know that this is not the original trans and I do not know what the specs are supposed to be for this one, a 32-8098M. I also don't know if I can get away with these specs, even though the radio must have worked at one time the way it was. Maybe they changed something else to make it work. I do not know enough about what I am doing to figure that out yet. What I do know is that when something is put together they way it was intended, I should not have to worry about that.
My question now then is, can I proceed or should I be looking for a correct trans?
(This post was last modified: 07-16-2015, 10:33 PM by MarkBardenwerper.)
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