Anybody have a guess as to the resistance of the field coil resistance on a Crosley 58? It is center tapped, but there seems to be no reason for it - yes both sides are open.. If I have to guess I'm going to wind for weight.

If it's open either side of the centre that could be a corrosive joint? If you join copper to other metals it often pays to coat the joint.. Do you have the circuit? often that will tell you, or allow you to compute it.

Otherwise, your right same guage & accurate scales.

Marc

I have disassembled it. It seems to have multiple open(s) not at the wire connections.

I see that a Crosley 48 specs a PN 45187 at 750 ohms for a draw of 75 MA for a similar circuit. I can’t find the spec for the coil on the 58 on any of the drawings.

Didn't see a center tapped speaker field in the schematic?

http://www.nostalgiaair.org/PagesByMode ... 039654.pdf

Schematic does mention see Model 54 for voltages. Using that you can adjust reistance for proper voltage. Your method of using weight will work if wire ga is known. A thousand ohms is common. Finding 750 on another schematic is reasonable.

http://www.nostalgiaair.org/PagesByMode ... 039648.pdf

Norm,

See the difference in the 54 and the 58. The 58 supplies a voltage to the FC which then goes to ground rather than the plate of the 45 as in the model 54 - yah I studied this for a while. The 750 ohm coil would seem right for the 54 but not the 58, which, after weighing the original coil, my new one using # 39 came out to about 5.5K ohms. I tapped it at 1K (the original was tapped, for no reason that I could find - unless they used it for both models) so just in case.

I'll let you know what works.


Oh, and the 54 is cap coupled to the speaker my 58 has an OP transformer.

And another thing- the schematic for the 58 shows the caned- ohm resistors (3) at 10K each, which some previous tech replaced accordingly. But if you check the parts list they are 3.2K. SO, I opened one of the failed ones and measured the continuous segment that was left. The parts list was correct, the schematic, not so much. I think I have had these issues with other Crosley drawings too.

I have an easier hassle where the radio has the same circuit as another, but a different original speaker assy. of the correct type and same brand but 500 Ohm lower field. They coud have changed the transformer but as in your case, if you come up low, WW resistors have been around a long time.

Have a look for a part number, it was not unusual for the same speaker assy. to appear in several other models. And if OEM (e.g. Plessey Rola here) other brands as well.

Marc

And the correct Jeopardy answer is - - - - - What is 10K ohms.

Current was too high at 5.5. The original wire may have been #40 or even #42. I wound enough #39 on to give me 9.33K, Works good - well as good as a 224, 224,224, 245 TRF is going to work.

I need the big shield for the 224s. It has Goat shields on STs now, which is OK but I would like to display it with the globes.

I could not resist the top and bottom plastic spacers to stiffen the coil form, especially after about a billion turns of # 39.

Great, you sure did that fast.

I have a few new radios to work on and not much time. So since the Buddy Boy was not going to need any extensive cabinet work, I fixed it first.

I think that green Zenith in the back may be last.

Lots of good information here. From what I have seen and read about there are basically 2 variations of field coil applications. First is a filter choke between first and second sections of voltage divider, typically between 700 and i500 ohms. Second variation is just a load in the voltage divider, typically much higher resistance, around 5000 ohms. A few other oddball ways to do it.