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 Post subject: Stewart Warner 950/565a wiring help
PostPosted: Apr Tue 07, 2020 10:27 pm 
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Location: 20653
I have a 950 chassis and a 565a speaker and the 4 pin connector and all wiring between the 2 is missing. I think I understand the connections but wan to be sure. I think the the Field coil connects to the pins that go to ground and the intersection of the 5k and 10k resistors, and the voice coil connects to the 2 sides of the output transformer. Am I correct? a few images below to help.


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Thanks,
Andy


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 Post subject: Re: Stewart Warner 950/565a wiring help
PostPosted: Apr Tue 07, 2020 10:40 pm 
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Can you post a link to the schematic you are using? In Rider's everything is laid out differently

EDIT: RM shows both US and Canadian versions of this---which one do you have?

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 Post subject: Re: Stewart Warner 950/565a wiring help
PostPosted: Apr Tue 07, 2020 10:50 pm 
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its from Gernsback volume 2 Supp 4 page 424L (page 32 of 64).


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 Post subject: Re: Stewart Warner 950/565a wiring help
PostPosted: Apr Tue 07, 2020 11:04 pm 
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I think your assumptions are correct, BUT: I am puzzled by a field coil being driven from such a high resistance....What is the DC resistance of the field coil?
And what are the 2 circles to the right of the 10K resistor?---maybe a shorting plug if you use a magnetic speaker?

Have you replaced capacitors?

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 Post subject: Re: Stewart Warner 950/565a wiring help
PostPosted: Apr Tue 07, 2020 11:35 pm 
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Not sure if I have a US unit or not. How do I check? The DC resistance is an interesting item. I can't find a value on a schematic or any other data, but others have measured and report that the DC resistance is 5k which when added to the 5k resistor inline gives 10k. When you use the PM speaker in place of a FC you connect the link ( the 2 circles to the right of the 10k resistor) that you mentioned which puts the 10k in play. So the DC resistance is the same whether using a PM or FC speaker. If you look at the 900 series information, the FC is listed as 1.8k. It appears Stewart Warner sold radios and speakers separate so maybe the FC resistance variance can be tolerated.


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 Post subject: Re: Stewart Warner 950/565a wiring help
PostPosted: Apr Tue 07, 2020 11:58 pm 
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Location: Austin, Texas
pixellany wrote:
I think your assumptions are correct, BUT: I am puzzled by a field coil being driven from such a high resistance....What is the DC resistance of the field coil?


The field coil is driven by the B+ so it will be a high resistance coil and doesn't need much current.

jay


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 Post subject: Re: Stewart Warner 950/565a wiring help
PostPosted: Apr Wed 08, 2020 12:06 am 
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Indeed!!---I have seen quite a few field coils in a "shunt" configuration, but I'm not sure I ever saw one with a 5K series resistor...
But then, I'm relatively new to to this....

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