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new project Sparton 75A

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new project Sparton 75A Empty new project Sparton 75A

Post by Ben Delk on Sun Oct 14, 2012 8:28 pm

https://servimg.com/view/17421296/63
https://servimg.com/view/17421296/64

Picked up this Sparton 75a a few months ago for $20. Put it on the workbench today, replaced the cord,and bless my ever humble soul, it plays......amazing. It does appear to have been touched a few times. There are several caps that are mis-matched brands and mfd ratings. This radio has tons of stuff under the hood and it is tight in there so slow going is the process here. I downloaded a schematic from Nostalgia and looks good but I'd like to know if anyone has a component layout. The schematic is very detailed with the cap and resistor ratings but I'd like to be sure of what I'm matching the replacement with. Just a little extra security there.....
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Post by Bill Cahill on Sun Oct 14, 2012 8:33 pm

Gee, Ben. Is that my Christmas present? I'll take it now.
Wish I had it. Nice find.
Bill Cahill
Lets' see under the hood.

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Post by Ben Delk on Mon Oct 15, 2012 5:59 pm

Ok Bill ....drive to Memphis and pick up your Christmas present. It would cost a small fortune to ship it. Oh and bring $20....ha! Here's under the hood you requested.
https://servimg.com/view/17421296/65
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Post by Bill Cahill on Mon Oct 15, 2012 7:25 pm

Looks like an interesting set Good luck. Take it slowly.......
Bill Cahill

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Post by Ben Delk on Tue Oct 16, 2012 9:19 am

Will do........question gentlemen....
This radio has 5 control knobs on the front and one on the back. The one on the back is volume control (odd place for that). On the front, from left to right, (#1)the left control is the multi-band selector (4 postions). (#2) no idea, maybe SW sensitivty??? . (#3) Middle control is tuning. (#4) seems to BC sensitivity since moving it much one way or the other I lose reception. (#5) is on/off switch and tone control. Do you think #2 is sensitivity?

http://www.nostalgiaair.org/PagesByModel/935/M0018935.pdf
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Post by Ben Delk on Sun Oct 21, 2012 8:08 pm

Sparton 75A update..
Spent most of the weekend working on this project. Was not as painful as I expected so things moved quickly, one component at a time. Gun shy after the Crosley ordeal.
Gave the chassis a light sanding, sprayed primer then 2 coats hammer tone gray. Working great, sounds great. Some of the pots were not as I thought. Pot #4 is volume. I'm not sure what to call the pot on the back but as I rotate it I lose reception or sound depending on where it works. Anyone have an idea what to call it.
https://servimg.com/view/17421296/70
https://servimg.com/view/17421296/71
https://servimg.com/view/17421296/72
https://servimg.com/view/17421296/73
https://servimg.com/view/17421296/74

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Post by Bill Cahill on Sun Oct 21, 2012 11:19 pm

If you are talking about that smaller adjustable capacitor, i'ts a tuned antenna circuit.
Bill Cahill

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Post by Ben Delk on Mon Oct 22, 2012 8:05 am

Makes sense....thanks
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Post by Ben Delk on Fri Oct 26, 2012 7:19 pm

Sparton is complete. This has been a fun project.

https://servimg.com/view/17421296/75
https://servimg.com/view/17421296/76
https://servimg.com/view/17421296/77
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