1949 Sparton 4900 AM/FM Radio Repair

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1949 Sparton 4900 AM/FM Radio Repair

Postby runnerredneck » Sat May 02, 2015 2:33 pm

I recently came into a Sparton 4900 Mirror In lid. I managed to get the record player to work, the TV is long gone (will soon be a liquor bar). The tube radio is there, and I would like to fix it up.

Good News: When I turn it on, the dash light turns on, and ALL the tubes do light up to some extent, and they become warm. Inside, it looks like it has never been touched and I do not see any burn marks. The wax paper capacitors all seem fine as well.

Bad news: I can not figure out the following
1. How the speakers would attach so I can see if it works.
2. What the 2 unconnected wires are that stick out next to the tuning plate.
3. What is the round female plug for?

I have a attached a few pictures. Any advise or help would be appreciated.
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Re: 1949 Sparton 4900 AM/FM Radio Repair

Postby battradio » Sat May 02, 2015 4:04 pm

Well you going to need a schematic , it appears to have an electrodynamic speaker and output transformer is most likely on it . It looks like it has its own power supply and output tube (7B5) but may have shared a speaker with the TV so you may have to figure out the wiring . The empty 4 pin socket is the speaker socket on the chassis . All the paper caps will need to be replaced and the electrolytics also
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Re: 1949 Sparton 4900 AM/FM Radio Repair

Postby runnerredneck » Sun May 03, 2015 9:41 am

How would you recommend findings a speaker plug?

Also, what were the purposes of the 2 wires sticking out near the tuning wheel? I suppose these are for the AM or FM but do i need to connect them to an antenna?
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Re: 1949 Sparton 4900 AM/FM Radio Repair

Postby DeathRex » Sun May 03, 2015 10:28 am

The plug with 2 wires going to it looks like audio in from the TV, have to see where it goes. The speaker plug looks to be just a 4 prong tube socket; you can use a bad 4 pin tube, remove the glass and you have plug. The 2 wires coming out are most probably the antenna and ground.
At first I wanted to be a ET. Now I are one.
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Re: 1949 Sparton 4900 AM/FM Radio Repair

Postby dcriner » Mon May 04, 2015 5:44 pm

First, you need a schematic and be able to read it, and have the usual electronic equipment. Here is one schematic that first popped up on Google: http://www.radiomuseum.org/r/sparks_wit ... _4900.html It might not be the best.

Study the schematic, and verify that the radio is stand-alone, and didn't share any components, such as power supply, etc., with the (now missing) TV. Otherwise, you will be in trouble.

Don't start replacing ANY parts - first, you need to get the radio working, after a fashion, by troubleshooting in a systematic manner, as necessary. At most, there should be just one major problem (or maybe none) - but if you start replacing parts, willy-nilly, you will surely make one or more wiring mistakes, so then troubleshooting will become next to impossible. After replacing any part, check that the radio still works before going on. This is a rather complicated radio, and is not a good one to start on - better to start with an AC/DC, All-American Five, and work your way up from there.

1949 was Sparton's first year for making TVs. If you succeed in getting the radio working, don't expect it to be a great performer. Of course, the FM will be mono.

This forum is oriented toward hi-fi, not radios. Check out these sites: http://www.nostalgiaair.org/Forums/Indices/ http://antiqueradios.com/forums/index

Good luck.
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