The PHILCO Phorum
Model 39 40 Speaker value - Printable Version

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Model 39 40 Speaker value - Sourbone - 04-17-2010

I'm working on a Philco model 39 40. The field coil is open, and I'm figuring out what I need to do in replacing the speaker. I've got the parts list and schematic from Nostalgia air, but I'm not seeing a wattage value or ohms for the voice coil. Field coil looks like it's 865 ohms. Any suggestions? Thanks,

Dave

Re: Model 39 40 Speaker value - exray - 04-18-2010

Are you sure thats a field coil? Looks like a hi-z magnetic speaker in the diagram.

If so, you could simply use a replacement speaker (your choice) with a typical output transformer suitable for a 6K6 output.

Re: Model 39-40 Speaker value - Sourbone - 04-18-2010

The parts list says, field coil speaker part number 62 on the model 39-40. Part number 57 is cone and voice coil. I have read here on the phorum about replacing field coil speakers with permanent magnet speakers. I would be kind of guessing it's a 4 ohm voice coil. Thinking to replace the field coil with a 1000 ohm power resistor at 15 watts. I haven't done this before, but I've been reading about it.

Thanks for your help,

Dave

Re: Model 39 40 Speaker value - codefox1 - 04-18-2010

Agree 100% with what has been said. Any "universal" output transformer will probably work out OK. You might want to add an additional filter cap AFTER the 1 K power resistor, as the smoothing action of the field coil will not be there, and you could have a little more hum. 10 or 22 mf ought to do it, just make sure the voltage rating is high enough.

Since you have nothing to lose, check to see if there is any break in the coil that is open that you can get to and repair before you throw it out. Also make sure the cause of the open winding is not still present, as in a shorted output tube, bad socket, filter cap, or other component.

Good luck.

Re: Model 39 40 Speaker value - exray - 04-18-2010

I'm terribly sorry for the misinformation. I clicked on the 38-40 schematic instead of 39-40 before the early morning coffee kicked in.

Carry on.

-Bill