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 Post subject: Sony 4-203 external power supply
PostPosted: Oct Sun 27, 2019 7:38 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 308
Location: Windsor, CT USA
I recently restored (recapped) this set. What a job! I assumed that the battery pack delivered 12VDC, so I connected my 2 amp DC power supply to the rear of the set and turned it on. To my amazement, it produced a beautiful picture and sound! My question is: how do I replicate the power supply connection on the side of the set? I have no schematic and can't find one anywhere. I don't know what voltages are expected. There is a 3 prong connector. Is the input 12VDC? 12VAC? 117VAC? What's with the three prongs? Is one a ground? Thanks to all.


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 Post subject: Re: Sony 4-203 external power supply
PostPosted: Oct Mon 28, 2019 7:02 pm 
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Joined: Mar Tue 03, 2009 11:12 pm
Posts: 1548
Location: Hutchinson KS
I have one of those sets and a schematic at home, via Sams photofact. Just type in sony 4-203 in your browser and there is a schematic there. It is a weird adaptor!


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 Post subject: Re: Sony 4-203 external power supply
PostPosted: Oct Mon 28, 2019 11:56 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 308
Location: Windsor, CT USA
Tried Sony 4-203. The only schematic that came up was a partial one at radiomuseum. Does your schematic indicate the voltages at the three pins?


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 Post subject: Re: Sony 4-203 external power supply
PostPosted: Oct Tue 29, 2019 4:38 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1804
Location: 07450, New Jersey
This is part of the schematic from Radiomuseum that shows the power supply. 9 "C" cells gives 13.5 volts so the 12 volts you applied was correct. The AC supply is just stepdown transformer and a full wave bridge to provide approx 12 to 13.5 VDC. As you can see, only 2 of the 3 pins are used.


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 Post subject: Re: Sony 4-203 external power supply
PostPosted: Oct Tue 29, 2019 3:04 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 308
Location: Windsor, CT USA
Thanks! Just what I needed.


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 Post subject: Re: Sony 4-203 external power supply
PostPosted: Oct Tue 29, 2019 3:55 pm 
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Joined: Mar Tue 03, 2009 11:12 pm
Posts: 1548
Location: Hutchinson KS
mstamper beat me to it! I found the Sams I had which is basically the same except it shows a bit more detail of the various power supply configurations used on this set. The unused pin was used as the ac adapter power to the rechargeable battery, which I have never seen. This is a marvelously overdesigned set for a tiny portable! 34 transistors, 5 tiny rectifier tubes (quintipular?) for high voltage supply. Three sound IF, three video IF, three agc amp stages, etc! And the crt filament is derived from horizontal "pulse" transformer!


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