Electro-dynamic speaker connection question - Printable Version
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Electro-dynamic speaker connection question - Kahuna59 - 08-31-2023
Hi all, I'm restoring a Model 41-610 which was missing it's electro-dynamic speaker assy model 36-1524. I found a Fairbanks-Morse with similar specs at a reasonable price as a suitable replacement. My problem is figuring out which of the 4 wires coming out of the chassis connect to which of the 4 wires from the speaker assy (output trans and field coil). The schematic is all I have but I struggle with trying to trace wiring and the connector is not specifically called out on the schematic. Any suggestions on how to decipher? I VERY MUCH APRECIATE ANY help. Thanks.
RE: Electro-dynamic speaker connection question - morzh - 08-31-2023
The wires from the original speaker: the field coil will have connection to the rectifier's filament and both electrolytic caps. Then you take care of the output xfmr wiring.
RE: Electro-dynamic speaker connection question - Kahuna59 - 08-31-2023
OK, that does clear things up a bit. I think you helped get me on the right track. I know I have to get this step right before attempting any power or risk destroying all the work and $$ I've put it so far.
Thank you! Much appreciated.
RE: Electro-dynamic speaker connection question - Radioroslyn - 08-31-2023
I'm pretty sure on that set the output transformer is mounted to the chassis and is wired the 41 tube's plates and screen grid. The secondary and field coil are connected thru the speaker plug. Two of the connection should show a low resistance against each other (opt 2ndy). Like a an ohm or two. The other two should show a short the one or the other filter cap. Have Fun!
https://philcoradio.com/library/download/service%20info/yearbooks/1941/split/Part57-Philco%201941%20RMS%20Year%20Book.pdf
GL
RE: Electro-dynamic speaker connection question - Kahuna59 - 08-31-2023
Oh my gosh, you're right. I've lost my mind. Yeah, the OT is in the chassis, I stare at it every day and I highlight it on the schematic then I promptly forget it all when I see an OT attached to the speaker. Thanks so much for pointing that out. I definitely do not need to hook up two OTs.
I believe I get the field coil connections now but forgive me, I didn't quite follow the second part of your description. Were you saying the remaining two of the 4 speaker plug pins should show a short to one or the other filter cap?
Lord help me, I'm definitely going to slow walk this one....
RE: Electro-dynamic speaker connection question - morzh - 08-31-2023
Even easier, if the xfmr is on the chassis.
RE: Electro-dynamic speaker connection question - Radioroslyn - 08-31-2023
Sorry 1 pin should show a short to the + side of 91 and the other a short to the + side of 43A. That's where the fc connects. The other two are the vc.
The diagram is not drawn properly it looks like plate and fc connection are connected thru the plug but they aren't. I wouldn't know this except I have a 41-300 which the same set up. OBTW check the resistance from the screen grid to the plates of the 41's to see if the pri is good. Sometimes 1/2 or both sides are open.